Catalysts for Demetallation of Low-Temperature Coal Tar

Catalysts for Demetallation of Low-Temperature Coal Tar | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Catalysts for Demetallation of Low-Temperature Coal Tar Bowen Ma, Jiaqing Song, Yuhui Guo, Yuan Zhao, Bin An This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7200385/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract A variety of catalysts were prepared to investigate the effects of active metals and phosphorous on hydrodemetallation (HDM) and hydrodesulfurization (HDS) of a typical medium-temperature coal tar from Xinjiang in China. A dispersant is used to improve the dispersion of active components on the surface of the support compared with the catalysts without dispersant. The hydrodemetallation products of the autoclave under mild conditions were characterized by inductive coupled plasma emission spectrometer (ICP) and microcoulometer. The difficulty of metal removal is as follows: Mg>Na>Al>Ca>Fe. The combination of H 3 PO 4 , (NH 4 ) 6 Mo 7 O 24 ·4H 2 O, and Ni(NO 3 ) 2 ·6H 2 O precursors generated more type II "Ni-Mo-S" active phases, with the highest catalytic activity. The dispersant polyvinyl pyrrolidone (PVP) was beneficial for the dispersion of metals, forming highly dispersed active centers, thereby increasing the activity of the catalyst. The hydrogenation desulfurization and hydrogenation demetallation occur at the same active site. The catalyst showed good stability within 168 hours. NiMo catalysts Hydrodemetallation Low-temperature coal tar Metals in coal tar Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Low-Temperature coal tar is a by-product from coal pyrolysis, mainly produced in the north of Shaanxi and Xinjiang, China. In recent years, with the rapid development of low-rank coal pyrolysis technology, the output of low-temperature coal tar has increased significantly [1–2]. Compared with the high-temperature tar produced by the traditional coking industry, the low-temperature coal tar contains more alkanes, cycloalkanes and less polycyclic aromatic hydrocarbons, and is suitable for producing clean fuel oil and high value-added chemicals through hydrogenation[3–6]. A large number of metal compounds may exist in coal tar[7–8]. The existence of metal impurities can cause corrosion and scaling of pipelines and equipment. More importantly, metal impurities may generate solid metal sulfides in the hydrogenation process and deposits between the catalyst orifice and catalyst particles, resulting in catalyst poisoning and deactivation and increased bed pressure drop[9–10] and severely limits the utility of medium-temperature coal tar in production of derivative chemical commodities of high economic values. In order to ensure the activity of hydrogenation catalysts and the long-term stable operation of the hydrogenation unit, the metal content (iron, calcium, sodium) of the raw material must be removed to below 20 ppm before entering the fixed-bed reactor. The remaining < 20 ppm of metal entering the fixed bed is mainly removed by the hydrodemetallation catalyst generally loaded in the first reactor in the fixed bed hydrogenation reactor. This step is the key guarantee for the stable long-term operation of the hydrogenation unit[11–14]. Low-temperature coal tar hydrotreating inherits core concepts from residue hydrotreating, but its feedstock’s metals necessitate specialized catalyst development.While nickel and vanadium are the main metal impurities in residual oil, coal tar contains mainly iron, calcium, and sodium as the main metal impurites[15]. Coal tar has many similarities with residual oil and shale oil. Currently, the hydrogenation catalysts of residual oil are often used for the hydrogenation of coal tar fractions. However, there is a significant difference in the relative N and S content between coal tar and residual oil[16]. Nitrogen content in coal tar is higher than sulfur, while the reverse is observed in residual oil. The absolute sulfur and nitrogen content in coal tar is typically higher than that in residual oil. Based on the above reasons, there are research intersts in developing highly active hydrofining catalysts for coal tar. Some researchers have used Ni/W as active metals for the hydrodesulfurization of coal tar, and studied the effect of Ni/W ratio on the results[17–18]. Phosphorus, boron, and fluorine elements are used to modify hydrogenation desulfurization catalysts, which helps to disperse the active components and improve the hydrodesulfurization performance of the catalyst[19–21]. The synthetic catalysts were prepared to study the effect of Ni/Mo active metals, phosphorous on hydrodesulfurization, hydrodemetallation of medium coal tar. 2. Experimental 2.1. Preparation of support The dual-peak-pore-structure alumina support was synthesized by adding 2 g of surface-active enlarging agent into 110.0 g of deionized water to prepare a solution. 100.0 g of boehmite and 110.0 g of the aforementioned aqueous solution were slowly added to a kneader and kneaded for 30 minutes. The kneaded material was transferred into an extruder and extruded through the butterfly orifice plate, dried in an oven at 120℃ for 4h, and calcined in a muffle furnace at 930℃ for 4 h to obtain the final carrier sample. 2.2. Preparation of catalysts The four catalysts(C-1/C-2/C-3/C-4) were prepared by simultaneous impregnation of phosphoric acid, molybdenum trioxide and nickel nitrate in four different distribution ratios. Another three catalysts(C-5/C-6/C-7) were prepared by simultaneous impregnation of three different precursor combinations as follows: (1) Phosphoric acid, molybdenum trioxide, nickel acetate, (2) Phosphoric acid, ammonium heptamolybdate, nickel nitrate,(3) Diammonium hydrogen phosphate, ammonium heptamolybdate, nickel nitrate. All above catalysts were dried at 100℃ for 4 h and calcined at 500℃ for 4 h. 2.3. Characterization of support and catalysts The BET specific surface area, pore volume, and pore size distribution of support were measured by N 2 adsorption–desorption analysis at 77 K. Prior to the analysis, the samples were degassed for 8 h at 150℃. The microstructure and grain size of the samples were studied using a high-resolution transmission electron microscope (JEM-2010) from Japan Electronics Co., Ltd. Main technical indicators: point resolution of 0.23 nm, line resolution of 0.14 nm, acceleration voltage of 200 kV, amplification factor of 50-1500000 times. X-ray photoelectron spectroscopy (XPS) was conducted under an ultra-high vacuum on a VG Scientific ESCALAB 250 spectrometer with Mg Kα radiation. The binding energies were referenced to the C 1s at 284.6 eV. 2.4 Impurities content of feedstock and products Elemental analysis of metal content in feedstock and products of hydrogenation was determined using an ICPA6300 instrument (Thermo Electron, USA) by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after the samples were dissolved in sulfuric acid solution. A LC-4 micro coulometer analyzer (Luoyang-Shuangyang, China) with a sensitivity of 0.1 mg L − 1 S was applied to measure the total sulfur content in the feedstock and products. 2.5 Presulfiding of catalyst The oxide catalysts were sulfifided before an hydrogenation began. The vulcanizing agent is DMDs (CH 3 -S-S-CH 3 ), and the vulcanized oil is aviation kerosene with 2 wt% DMDs. The presulfiding conditions are: total pressure,12 MPa; hydrogen-to-hydrocarbon ratio, 1200; and liquid hourly space-velocity (LHSV, calculated on the basis of catalyst volume), 1.0 h − 1 . In order to achieve complete sulphurizing of the catalyst, the H 2 S concentration in the exhaust gas was constantly monitored during the presulfiding process of the catalyst. Complete sulphurizing was reached when the H 2 S concentration in the exhaust gas reached a constant. 2.6 Catalyst activity test The catalyst activity tests were performed in a high-pressure autoclave. The experimental conditions were: reaction temperature, 320 ℃, pressure, 4MPa, reaction time, 6h, determination of sulfur and metal content after cooling. 2.7 Catalyst stability test The catalyst stability test was performed in a 5 mL fixed-bed reactor. The stability test conditions are: reaction temperature, 320 ℃, pressure, 4MPa, liquid hourly space-velocity, 0.5h − 1 , hydrogen-to-hydrocarbon ratio, 600. 3. Results & discussion 3.1 Textural properties of support The pore size distribution of the support is presented in Fig. 1 . The textural properties show that the support prepared has mesoporous structure. The physical properties of the support are: surface area of 133 m 2 /g, pore volume 0.51 mL/g and average pore diameter 15.3 nm. Adsorption and desorption isotherms of the support are presented in Fig. 2 . The isotherms correspond to a type IV, which indicate the presence of mesopores. Based on the IUPAC classification, the hysteresis loop is classified as H2(b), which is associated with complex pore networks formed by particle aggregation. In contrast to H2(a) (ink-bottle pores with narrow neck distributions), H2(b) hysteresis loops arise from broader pore neck width distributions and pore blockage effects in aggregated structures[22–24]. The filling of the wide pores remains the same as before, but during the desorption stage, the pores remain filled until the adsorbed gas in the narrow pore neck evaporates and empties under lower vapor pressure, allowing the adsorbate in the wide pores to evaporate and desorb. In a pore network structure, the desorption vapor pressure depends on the size and spatial distribution of the pore necks. If the diameter of the pore neck is not too small, the pore network can start to empty at a relative pressure point, which is equivalent to the characteristic permeability threshold. 3.2. Properties of feedstock The feedstock for this study was a fraction below 400 ℃ from a coal tar hydrogenation plant. The origin of low temperature coal tar of this factory was from Hami, Xinjiang, China. The physico-chemical properties of the feedstock are given in Table 1 . Table 1 Feedstock properties and its metal content S/ppm Mental/ppm Cl/ppm Carbon residue(%) Density(g/cm3) Na Mg Al Ca Fe 1918.01 16.54 2.59 1.41 2.08 10.31 19.32 0.35 0.979 3.3. Effect of active components content on HDM and HDS activities (1)Catalyst active components loading ratio In this study, four catalysts were prepared by equal volume impregnation method using precursors including H 3 PO 4 , MoO 3 and Ni(NO 3 ) 2 · 6H 2 O(Table 2 ). Table 2 Catalyst active components loading ratio Component/% MoO 3 NiO P 2 O 5 Addition amount of precursor components C-1 9.80 3.1 2.5 0.48g H 3 PO 4 + 1.16g MoO 3 + 1.43g Ni(NO 3 ) 2 · 6H 2 O + 10g Al 2 O 3 C-2 8.48 1.21 3.92 0.74g H 3 PO 4 + 0.98g MoO 3 + 0.55g Ni(NO 3 ) 2 · 6H 2 O + 10g Al 2 O 3 C-3 6.88 0.48 3.25 0.59g H 3 PO 4 + 0.77g MoO 3 + 0.21g Ni(NO 3 ) 2 · 6H 2 O + 10g Al 2 O 3 C-4 8.75 3.14 3.87 0.75g H 3 PO 4 + 1.04g MoO 3 + 1.43g Ni(NO 3 ) 2 · 6H 2 O + 10g Al 2 O 3 (2)Catalyst activity evaluation After obtaining catalysts with different loading amounts of active components, the catalyst activity was studied in an autoclave by measuring desulfurization and demineralization rates after hydrogenation of the coal tar. Results are presented in Table 3 . Table 3 The desulfurization rate and demineralization rate after hydrogenation of the coal tar Desulfurization rate, % Demetallation rate, % Na Mg Al Ca Fe C-1 58.81 73.70 65.38 73.05 65.64 91.76 C-2 68.31 83.43 78.38 86.52 91.83 96.02 C-3 35.64 58.10 33.98 47.52 59.62 68.96 C-4 62.43 76.96 66.80 81.56 71.63 94.08 The activities of catalysts for demetallation and desulfurization are ranked in decreasing order as C-2>C-4>C-1>C-3. The order of metal removal rates from lowest to highest s as follows: Mg>Na>Al>Ca>Fe. For C-2, although its active metal content is not the highest, it exhibits the best performance of demetallation and desulfurization in all four catalysts prepared, including the removal of Ca and Al, which are difficult to remove[25].During sulfidation, two distinct phases Type I and Type II can form, differing in both the extent of sulfidation and the strength of metal-support interactions[26–28]. Type I corresponds to incomplete sulfidation and arises when metal-support interactions are strong. Such strong interactions anchor the metal species to the support surface, limiting their migration and reactivity toward sulfidation. As a result, the metal-sulfide slabs exhibit a low stacking degree, exposing fewer catalytically active edge sites and thus diminishing catalytic performance. In contrast, Type II represents complete sulfidation, which typically occurs under weak metal-support interactions. Here, the metal species can migrate freely and undergo full sulfidation, forming highly stacked layered sulfide structures. The increased abundance of exposed active edge sites leads to significantly enhanced catalytic performance. The results indicate that there are more type II Ni-Mo-S active phases on C-2 catalyst compared to other catalysts. From the Table 2 , C- 3 catalyst contains the lowest content of active metals Ni and Mo compared to the other three catalysts despite its high P content. As the result suggests, C-3 provided insufficient catalytic activity of C-3, ultimately leading to lower desulfurization and demetallation rates of coal tar. Mo and P contents in C-2 and C-4 were relatively close, with Ni/Mo content of C-2 catalyst being lower than C-4. However, C-2 exhibited superior catalytic performance, indicating the existence of an optimal value for Ni/Mo. 3.4 Effect of active component precursors on HDM and HDS activities (1) Catalyst characterization To investigate the effect of precursor slection on catalyst activity, C-6, C-7 and C-8 catalysts were prepared with the identical content of active components as with C-2 but using different active precursors. The precursor combinations of the catalysts are shown in Table 4 . Table 4 Composition of active components of catalysts under different precursor conditions Catalysts Addition of precursor components C-2 0.74g H 3 PO 4 + 0.98gMoO 3 + 0.55gNi(NO 3 ) 2 · 6H 2 O + 10gAl 2 O 3 C-6 0.74g H 3 PO 4 + 0.98gMoO 3 + 0.47gNi(OCOCH 3 ) 2 · 4H 2 O + 10gAl 2 O 3 C-7 0.74gH 3 PO 4 + 1.21g(NH 4 ) 6 Mo 7 O 24 · 4 H 2 O + 0.2gPVP + 0.55gNi(NO 3 ) 2 · 6H 2 O + 10gAl 2 O 3 C-8 0.85gNH 4 H 2 PO 4 + 1.21g(NH 4 ) 6 Mo 7 O 24 · 4 H 2 O + 5gNH 4 OH + 0.55gNi(NO 3 ) 2 · 6H 2 O + 10gAl 2 O 3 The four catalysts (C-7/C-6/C-2/C-8) were characterized and analyzed by X-ray Photon-electron Spectroscopy. The energy spectrum data of the obtained samples were fitted and analyzed using software XPSPEAK 4.1. The results in Fig. 3 showed changes in the content of Mo 6+ , Mo 5+ , and Mo 4+ catalysts prepared from different precursors. According to literature reports[29], the binding energies of Mo 6+ , Mo 5+ , and Mo 4+ are approximately 232.6 ± 0.2eV, 230.6 ± 0.2eV, and 228.7 ± 0.2eV, respectively. They are the three common valence states of Mo based catalysts, and all three valence states may exist under reducing conditions. Among them, Mo 4+ is generally believed to be related to the activity of Ni-Mo-S, and the higher its proportion, the better the catalyst activity[29]. Fitting Mo 3d 5/2 spectra in Fig. 3 . by using software gives Mo6+, Mo5+, and Mo4 + contents as shown in Table 5 . The order of Mo 4+ percentage is C-7 > C-6 > C-2 > C-8. This analysis is further supported by comparison of different Ni forms prepared by different precursors. The order of area size attributed to Ni-Mo-S is C-7 > C-6 > C-2 > C-8. Table 5 Comparison of Mo 6+ , Mo 5+ , Mo 4+ content in catalysts prepared by different precursors Catalyst Mo 6+ Mo 5+ Mo 4+ Mo 4+ % BE(e.v) (Area) BE(e.v) (Area) BE(e.v) (Area) C-2 232.49 42064.13 230.59 8927.66 229.01 25439.88 33.28 C-6 232.39 44308.07 230.79 13494.99 229.37 31534.21 35.30 C-7 232.46 43576.28 230.86 8354.79 229.25 30685.13 37.14 C-8 232.35 39665.85 230.53 6955.29 229.00 21352.05 31.41 Table 6 Comparison of Ni compounds prepared by different precursors Catalyst Satellite Ni 2+ NiMoS NiSx BE(e.v) (Area) BE(e.v) (Area) BE(e.v) (Area) BE(e.v) (Area) C-2 862.39 6809.39 857.55 5273.33 856.43 4694.45 853.85 1449.46 C-6 862.48 5952.56 857.78 3094.49 856.33 6060.80 853.86 1723.68 C-7 862.53 8178 857.7 2701 856.33 6780.48 853.73 2863.83 C-8 862.67 4716.89 857.87 5744.55 856.45 4381.43 853.84 1015.85 A large number of layered MoS 2 particles with an interplanar spacing of 0.641 nm can be observed in Fig. 5 through high-resolution transmission electron microscopy (HRTEM) images. The catalyst generated MoS 2 after presulfurization, which served as the active center for hydrogenation desulfurization. A large number of MoS 2 lattice fringes can be observed in catalysts C-6 and C-7, in a stark contrast to the images of C-2 and C-8. In particular, catalyst C-7 showed not only has more MoS 2 lattice stripes, but also more stacking layers, which could be attributed for its best performance[30]. The PVP dispersant was added during the preparation of C-7 catalyst. The results indicate that the dispersant PVP is beneficial for the dispersion of metals, forming highly dispersed active centers and obtaining the most optimal catalyst performance[31]. C-2 and C-8 samples have fewer MoS 2 stripes, resulting in larger MoS 2 particles and poor metal dispersion. Especially in sample 8, large particles of MoS 2 can be observed, which was the reason for the lower activity of samples 2 and 8. There are two Co (Ni) - Mo (W) - S phases in Co (Ni) - Mo (W) sulfide loaded onγ- Al 2 O 3 . The type I structures typically consist of a single-layer MoS 2 phase, which strongly interacts with Al 2 O 3 through chemical bonds such as Mo-O-Al and Ni-O-Al. The Type I active phase is not fully sulfided and has less stacking, while the Type II active phase is fully sulfided and highly stacked, with weaker interaction. Due to the strong interaction between the Type I active phase with Al 2 O 3 , the Type I active phase usually has better dispersibility. But compared to the Type II active phase, its incomplete sulfurization characteristics endow it with relatively lower HDS activity. The weak interaction between type II active phase with Al 2 O 3 , i.e. van der Waals interaction, weakens dispersion but improves the stacking of MoS 2 and leads to complete sulfurization. According to Topsøe et al. [32], the type II active phase may also exist in the form of a single-layer MoS 2 phase, indicating that high stacking is not a fundamental characteristic of type II active phase. The activity of type II active phase is approximately twice that of type I active phase. The weak interaction with Al 2 O 3 creates more reaction space around the edges of type II active phases, which facilitates the adsorption of large sulfur-containing compounds such as DBT and 4,6-DMDBT, thereby enhancing HDS activity [33–34]. (2)Catalyst activity evaluation The hydrogenation reaction was conducted at 320°C under a pressure of 4 MPa for a duration of 6 hours. When the temperature inside the autoclave was equilibrated to room temperature, the samples were taken for analyses of sulfur and metal contents. Results were provided in Table 7 . The desulfurization rate of the four catalyst studies is ranked in decreasing order as C-7 > C-6 > C-2 > C-8, with desulfurization rates of 84.45%, 73.39%, 68.31%, and 55.66%, respectively. The activity order of demetallation was consistent with that of desulfurization, indicating that hydrogenation desulfurization and hydrogenation demetallation occur at the same active site. The higher the catalyst activity, the higher the activity of hydrogenation desulfurization and hydrogenation demetallation. The results of hydrogenation desulfurization and hydrogenation demetallation were consistent with the XPS characterization of Mo 4+ ratio and Ni-Mo-S ratio, indicating the high likelihood that Ni-Mo-S was the active phase on which hydrogenation desulfurization and hydrogenation demetallation reactions occured. From the HRTEM spectrum in Fig. 5 ., it can be seen that C-6 and C-7 have more Ni-Mo-S active phases, resulting in higher hydrogenation desulfurization and demetallation performance than C-2 and C-8. Table 7 The desulfurization rate and demetallation rate of catalysts prepared by different precursors Catalyst Desulfurization rate, % Demetallation rate, % Na Mg Al Ca Fe C-2 68.31 83.43 78.38 86.52 91.83 96.02 C-6 73.39 88.81 72.20 90.78 93.27 96.61 C-7 84.45 95.10 95.37 96.45 95.67 96.90 C-8 55.66 70.86 63.32 68.09 96.15 90.88 3.5 Catalyst stability (1) Fixed-bed continuous-flow micro-reaction equipment Based on the results from catalyst activity evaluation in autoclave, the optimal catalyst C-7 with the best hydrogenation performance was selected for the fixed bed continuous-flow evaluation. To study its demetallation stability, investigation was conducted on a 5ml fixed bed evaluation device made of stainless steel. The process flow diagram of the fixed bed evaluation device (as shown in Fig. 6 .) mainly includes six unit operations, namely: gas path and its control system, liquid path and its control system, micro fixed bed reactor, gas-liquid separator, liquid receiver, and tail gas measurement and detection system. The reactor has an inner diameter of 8 mm and a length of approximately 40 cm and is made of stainless steel material. The length of the constant temperature zone is about 10 cm. A temperature measuring sleeve is installed inside the reactor, extending from the lower part to the middle of the reactor to accurately measure the reaction temperature. After pressure reduction and stabilization, the hydrogen gas is measured and controlled by a gas mass flow meter to a set value and mixed with the raw oil from the raw oil pump. The raw oil is measured by a high-pressure metering pump and pressurized before being mixed with hydrogen gas into the upper part of the reactor. The raw oil and hydrogen were preheated to the reaction temperature in the preheating furnace placed at the top of the reactor, and then entered the catalyst bed for hydrogenation reaction under isothermal conditions. The oil generated by hydrogenation and excess unreacted hydrogen gas flowed out from the lower part of the reactor, entered the gas-liquid separator through a water-cooled heat exchanger, and the gas was discharged through a gas flow meter. This device is equipped with insulation for raw oil tanks, raw oil pumps, raw oil pipelines, production oil pipelines, production oil tanks, etc. The insulation temperature can reach up to 150 ℃ and can be adjusted. It can be used in special situations where the freezing point of raw oil and production oil is higher than the ambient temperature. Catalyst stability test The reaction conditions for the catalyst stability test were set as follows: the reaction temperature was 320 ℃, the pressure was 4 MPa, the mass space velocity was 0.5 h − 1 , the hydrogen-to-oil volume ratio was 600, and the catalyst loading was 5 mL. Under these conditions, a 168-hour stability test was conducted on the catalyst, with samples collected every 24 hours to analyze sulfur and metal content. Desulfurization and demetallation rates were calculated and provided in Table 8 . Table 8 The desulfurization rate and demetallation rate of catalyst C-7 at different reaction times Reaction time/h Desulfurization rate, % Demetallation rate, % Na Mg Al Ca Fe 24 84.45 95.1 95.37 96.45 95.67 96.9 48 87.12 94.23 95.21 96.23 95.33 96.32 72 85.05 95.3 95.36 95.21 94.25 95.3 96 84.69 94.63 94.63 94.63 94.23 94.32 120 83.65 96.32 97.65 93.52 97.52 97.21 144 85.74 95.21 93.25 94.21 96.25 96.3 168 86.21 94.66 94.32 92.33 94.21 95.1 The stability of crude oil processing catalysts is an important parameter. The metal holding capacity and surface coking inhibition ability of catalysts are key factors affecting the stability. The metal sulfides and carbon deposits deposited in the middle of catalyst particles can hinder the effective utilization of catalyst pore volume [35]. From the Fig. 6 , the variation of catalyst desulfurization rate with reaction time showed that the desulfurization rate of catalyst C-7 can remain stable at around 85% within the investigated time range, and there was no phenomenon of desulfurization activity degradation. It showed that catalyst C-7 had good removal ability for elements such as Na, Mg, Al, Ca, Fe, etc. The removal rate of these metal was about 95%, and it was stable within 168 hours without any degradation of demetallation performance. The catalyst C-7 had high stability, which was due to the larger pore volume of the prepared catalyst. The larger pore volume can accommodate more metals. 4. Conclusion The high activity of catalysts for hydrodemetallation of low-temperature coal tar requires a suitable Ni/Mo. In all synthesized catalysts studied, the highest active metal content in a catalyst did not result in the highest catalytic activity for demetallation and desulfurization. Importantly, the activity pattern of demetallation was observed to be consistent with that of desulfurization, indicating that hydrogenation desulfurization and hydrogenation demetallation may occur at the same active site. C-6 and C-7 have more Type II active phases, resulting in higher hydrogenation desulfurization and demetallation performance than C-2 and C-8. The dispersant PVP is beneficial for the dispersion of metals, forming highly dispersed active centers, thereby increasing the activity of the catalyst. The C-7 catalyst is basically stable within 168 hours and has good removal ability for elements such as Na, Mg, Al, Ca, Fe, etc., with a removal rate of about 95%, without any degradation in the performance of metal removal and desulfurization. Declarations Acknowledgements The authors would like to thank the technical support from the Coal Chemical Research Institute of China Coal Research Institute Co., Ltd. This work was supported by the National Key Research and Development Program of China (2023YFB4103002). Author Contributions Bowen Ma: Conceptualization, Methodology, Investigation, Writing - Original Draft. Jiaqing Song: Supervision, Funding Acquisition, Writing - Review & Editing. Yuhui Guo, Yuan Zhao, Bin An: Data Curation, Validation, Experimental Assistance. Conflicts of Interest The authors declare no conflicts of interest. Data and Code Availability The data supporting the findings of this study are available from the corresponding author (Jiaqing Song) upon reasonable request. Supplementary Materials Not applicable. Ethical Approval Not applicable (this study does not involve human subjects or animal experiments). References Li C S, Suzuki K (2010) Resources, properties and utilization of tar. Resour Conserv Recycl 54:905–915. Xie K C, Li W Y, Zhao W (2010) Coal chemical industry and its sustainable development in China. Energy 35:4349–4355. 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Wang R, et al (2017) Pilot-plant study of upgrading of medium and low-temperature coal tar to clean liquid fuels. Fuel Process Technol 155:153–159. Wei Q, et al (2023) Rhenium modification on NiMo/Al2O3 catalyst and effects on the hydrodesulfurization reaction route selectivity of 4,6-dimethyldibenzothiophene. Catal Today 407:281–290. Hinnemann B, Nørskov J K, Topsøe H (2005) A density functional study of the chemical differences between type I and type II MoS2-based structures in hydrotreating catalysts. J Phys Chem B 109:2245–2253. Van Veen J A R, et al (1993) On the formation of type I and type II NiMoS phases in NiMo/Al2O3 hydrotreating catalysts and its catalytic implications. Fuel Process Technol 35:137–157. Dong Y Y, Chen Z, Xu Y R, Yang L F, Fang W P, Yi X D (2017) Template-free synthesis of hierarchical meso-macroporous γ-Al2O3 support: Superior hydrodemetallization performance. Fuel Process Technol 168:65–73. Kwao S, et al (2024) Review of current advances in hydrotreating catalyst support. J Ind Eng Chem 135:1–16. Liu H, et al (2017) Effect of NiMo phases on the hydrodesulfurization activities of dibenzothiophene. Catal Today 282:222–229. Topsøe H (2007) The role of Co–Mo–S type structures in hydrotreating catalysts. Appl Catal A: Gen 322:3–8. Tuxen A K, Füchtbauer H G, Temel B, Hinnemann B, Topsøe H, Knudsen K G, Besenbacher F, Lauritsen J V (2012) Atomic-scale insight into adsorption of sterically hindered dibenzothiophenes on MoS2 and Co–Mo–S hydrotreating catalysts. J Catal 295:146–154. Besenbacher F, Lauritsen J V (2021) Applications of high-resolution scanning probe microscopy in hydroprocessing catalysis studies. J Catal 403:4–15. Rana M S, Ancheyta J, Maity S K, Rayo P (2005) Characteristics of Maya crude hydrodemetallization and hydrodesulfurization catalysts. Catal Today 104:86–93. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revision 30 Jan, 2026 Reviewers agreed at journal 04 Aug, 2025 Reviewers invited by journal 04 Aug, 2025 Editor invited by journal 28 Jul, 2025 Editor assigned by journal 25 Jul, 2025 First submitted to journal 23 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7200385","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":495140257,"identity":"a34312d2-5159-45c0-b2cb-0260fb539039","order_by":0,"name":"Bowen Ma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvUlEQVRIiWNgGAWjYBAC+/bmgw8+VNjIybM3EKnFgOdYsuGMM2nGhj0HiNUi4WMmzdl2OJHhRgKRWswl2JKNGdsOJzDOfLzxBkONTTRBLZazmw8+LjiXnscunVZswXAsLbeBoJ47x5KNZ5RZFzPOzjGTYGw4TISWGzlm0jxszIkNN88QqcUArKXNObHhBg+RWiR74IEM9EsCMX7hZ4dH5eGNNz7U2BDhF2RHSiSQohyihVQdo2AUjIJRMDIAAI7ORHk4IpAIAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0003-5474-8030","institution":"China Coal Technology and Engineering Group","correspondingAuthor":true,"prefix":"","firstName":"Bowen","middleName":"","lastName":"Ma","suffix":""},{"id":495140258,"identity":"cc223531-710a-41e5-bbcb-15484eeb3d07","order_by":1,"name":"Jiaqing Song","email":"","orcid":"","institution":"Beijing University of Chemical Technology College of Chemistry","correspondingAuthor":false,"prefix":"","firstName":"Jiaqing","middleName":"","lastName":"Song","suffix":""},{"id":495140259,"identity":"7229b51f-671b-45d2-af3d-c1878e78ceed","order_by":2,"name":"Yuhui Guo","email":"","orcid":"","institution":"China Coal Technology and Engineering Group","correspondingAuthor":false,"prefix":"","firstName":"Yuhui","middleName":"","lastName":"Guo","suffix":""},{"id":495140260,"identity":"8fe8b247-2f24-4fec-b241-68268b64f7e6","order_by":3,"name":"Yuan Zhao","email":"","orcid":"","institution":"China Coal Science and Industry Group Co Ltd: China Coal Technology and Engineering Group","correspondingAuthor":false,"prefix":"","firstName":"Yuan","middleName":"","lastName":"Zhao","suffix":""},{"id":495140261,"identity":"622d4ea8-12ab-4db9-a53f-98ea6fa01368","order_by":4,"name":"Bin An","email":"","orcid":"","institution":"China Coal Technology and Engineering Group","correspondingAuthor":false,"prefix":"","firstName":"Bin","middleName":"","lastName":"An","suffix":""}],"badges":[],"createdAt":"2025-07-24 01:50:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7200385/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7200385/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":88528990,"identity":"4d9b3056-1993-4ecb-a47c-baab295a06a2","added_by":"auto","created_at":"2025-08-07 10:56:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":48540,"visible":true,"origin":"","legend":"\u003cp\u003ePore-size distributions of the γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/56675158f5d5e8414387f00c.png"},{"id":88529219,"identity":"a06d4199-ce0e-4988-814b-3bd03c826fd1","added_by":"auto","created_at":"2025-08-07 11:04:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":60093,"visible":true,"origin":"","legend":"\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e adsorption (solid)–desorption (dotted) isotherm of γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/54cf49fe29b87e5d79e36040.png"},{"id":88529926,"identity":"045483ba-e15d-4e2e-aafd-5ca2d9dbb0c0","added_by":"auto","created_at":"2025-08-07 11:12:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":27413,"visible":true,"origin":"","legend":"\u003cp\u003eXPS spectra showing the binding energies of molybdenum in C-7/C-6/C-2/C-8 catalysts\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/432434a77f7176146a259bec.png"},{"id":88528993,"identity":"43f1706d-775a-4b7f-8c89-d17106f7575b","added_by":"auto","created_at":"2025-08-07 10:56:24","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":38477,"visible":true,"origin":"","legend":"\u003cp\u003eXPS spectra showing the binding energies of nickel in C-7/ C-6/ C-2/ C-8 catalysts\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/dc10cf47c6b0ba7318326ed3.png"},{"id":88529222,"identity":"2bf31170-bd07-4c5c-89c7-6b828ee2458d","added_by":"auto","created_at":"2025-08-07 11:04:24","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":228822,"visible":true,"origin":"","legend":"\u003cp\u003eHRTEM spectra of catalysts prepared from different precursors\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/8cfa347917b289acf94e09e0.jpg"},{"id":88529927,"identity":"0843c904-0f03-485f-b8d3-8fa5cab098d8","added_by":"auto","created_at":"2025-08-07 11:12:24","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":160514,"visible":true,"origin":"","legend":"\u003cp\u003eProcess flow diagram of 5 mL fixed bed continuous flow micro reaction equipment\u003c/p\u003e","description":"","filename":"floatimage9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/01226b4989b3090498d413a2.jpeg"},{"id":88529224,"identity":"67788f89-bedd-4555-a002-1f994107aed5","added_by":"auto","created_at":"2025-08-07 11:04:24","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":50410,"visible":true,"origin":"","legend":"\u003cp\u003eThe variation of desulfurization rate with reaction time\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/0a8f08c47579a5e860d34466.png"},{"id":88529928,"identity":"cb5ee97e-5a61-4bb4-8e0c-f67023920990","added_by":"auto","created_at":"2025-08-07 11:12:24","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":70577,"visible":true,"origin":"","legend":"\u003cp\u003eThe variation of demetallation rate with reaction time\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/fd9a1957ac3b8667f1c333f6.png"},{"id":88530987,"identity":"d8327b3b-6ee8-45f2-ae25-93ed59cd0884","added_by":"auto","created_at":"2025-08-07 11:28:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1639011,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7200385/v1/3bf37cc3-4c3e-4352-826a-d13e09e53038.pdf"}],"financialInterests":"","formattedTitle":"Catalysts for Demetallation of Low-Temperature Coal Tar","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eLow-Temperature coal tar is a by-product from coal pyrolysis, mainly produced in the north of Shaanxi and Xinjiang, China. In recent years, with the rapid development of low-rank coal pyrolysis technology, the output of low-temperature coal tar has increased significantly [1\u0026ndash;2]. Compared with the high-temperature tar produced by the traditional coking industry, the low-temperature coal tar contains more alkanes, cycloalkanes and less polycyclic aromatic hydrocarbons, and is suitable for producing clean fuel oil and high value-added chemicals through hydrogenation[3\u0026ndash;6].\u003c/p\u003e\u003cp\u003eA large number of metal compounds may exist in coal tar[7\u0026ndash;8]. The existence of metal impurities can cause corrosion and scaling of pipelines and equipment. More importantly, metal impurities may generate solid metal sulfides in the hydrogenation process and deposits between the catalyst orifice and catalyst particles, resulting in catalyst poisoning and deactivation and increased bed pressure drop[9\u0026ndash;10] and severely limits the utility of medium-temperature coal tar in production of derivative chemical commodities of high economic values.\u003c/p\u003e\u003cp\u003eIn order to ensure the activity of hydrogenation catalysts and the long-term stable operation of the hydrogenation unit, the metal content (iron, calcium, sodium) of the\u003c/p\u003e\u003cp\u003eraw material must be removed to below 20 ppm before entering the fixed-bed reactor. The remaining\u0026thinsp;\u0026lt;\u0026thinsp;20 ppm of metal entering the fixed bed is mainly removed by the hydrodemetallation catalyst generally loaded in the first reactor in the fixed bed hydrogenation reactor. This step is the key guarantee for the stable long-term operation of the hydrogenation unit[11\u0026ndash;14]. Low-temperature coal tar hydrotreating inherits core concepts from residue hydrotreating, but its feedstock\u0026rsquo;s metals necessitate specialized catalyst development.While nickel and vanadium are the main metal impurities in residual oil, coal tar contains mainly iron, calcium, and sodium as the main metal impurites[15].\u003c/p\u003e\u003cp\u003eCoal tar has many similarities with residual oil and shale oil. Currently, the hydrogenation catalysts of residual oil are often used for the hydrogenation of coal tar fractions. However, there is a significant difference in the relative N and S content between coal tar and residual oil[16]. Nitrogen content in coal tar is higher than sulfur, while the reverse is observed in residual oil. The absolute sulfur and nitrogen content in coal tar is typically higher than that in residual oil. Based on the above reasons, there are research intersts in developing highly active hydrofining catalysts for coal tar. Some researchers have used Ni/W as active metals for the hydrodesulfurization of coal tar, and studied the effect of Ni/W ratio on the results[17\u0026ndash;18]. Phosphorus, boron, and fluorine elements are used to modify hydrogenation desulfurization catalysts, which helps to disperse the active components and improve the hydrodesulfurization performance of the catalyst[19\u0026ndash;21].\u003c/p\u003e\u003cp\u003eThe synthetic catalysts were prepared to study the effect of Ni/Mo active metals, phosphorous on hydrodesulfurization, hydrodemetallation of medium coal tar.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Preparation of support\u003c/h2\u003e\u003cp\u003eThe dual-peak-pore-structure alumina support was synthesized by adding 2 g of surface-active enlarging agent into 110.0 g of deionized water to prepare a solution. 100.0 g of boehmite and 110.0 g of the aforementioned aqueous solution were slowly added to a kneader and kneaded for 30 minutes. The kneaded material was transferred into an extruder and extruded through the butterfly orifice plate, dried in an oven at 120℃ for 4h, and calcined in a muffle furnace at 930℃ for 4 h to obtain the final carrier sample.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Preparation of catalysts\u003c/h2\u003e\u003cp\u003eThe four catalysts(C-1/C-2/C-3/C-4) were prepared by simultaneous impregnation of phosphoric acid, molybdenum trioxide and nickel nitrate in four different distribution ratios. Another three catalysts(C-5/C-6/C-7) were prepared by simultaneous impregnation of three different precursor combinations as follows: (1) Phosphoric acid, molybdenum trioxide, nickel acetate, (2) Phosphoric acid, ammonium heptamolybdate, nickel nitrate,(3) Diammonium hydrogen phosphate, ammonium heptamolybdate, nickel nitrate. All above catalysts were dried at 100℃ for 4 h and calcined at 500℃ for 4 h.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Characterization of support and catalysts\u003c/h2\u003e\u003cp\u003eThe BET specific surface area, pore volume, and pore size distribution of support were measured by N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption analysis at 77 K. Prior to the analysis, the samples were degassed for 8 h at 150℃. The microstructure and grain size of the samples were studied using a high-resolution transmission electron microscope (JEM-2010) from Japan Electronics Co., Ltd. Main technical indicators: point resolution of 0.23 nm, line resolution of 0.14 nm, acceleration voltage of 200 kV, amplification factor of 50-1500000 times. X-ray photoelectron spectroscopy (XPS) was conducted under an ultra-high vacuum on a VG Scientific ESCALAB 250 spectrometer with Mg Kα radiation. The binding energies were referenced to the C 1s at 284.6 eV.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Impurities content of feedstock and products\u003c/h2\u003e\u003cp\u003eElemental analysis of metal content in feedstock and products of hydrogenation was determined using an ICPA6300 instrument (Thermo Electron, USA) by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after the samples were dissolved in sulfuric acid solution. A LC-4 micro coulometer analyzer (Luoyang-Shuangyang, China) with a sensitivity of 0.1 mg L\u0026thinsp;\u0026minus;\u0026thinsp;1 S was applied to measure the total sulfur content in the feedstock and products.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Presulfiding of catalyst\u003c/h2\u003e\u003cp\u003eThe oxide catalysts were sulfifided before an hydrogenation began. The vulcanizing agent is DMDs (CH\u003csub\u003e3\u003c/sub\u003e-S-S-CH\u003csub\u003e3\u003c/sub\u003e), and the vulcanized oil is aviation kerosene with 2 wt% DMDs. The presulfiding conditions are: total pressure,12 MPa; hydrogen-to-hydrocarbon ratio, 1200; and liquid hourly space-velocity (LHSV, calculated on the basis of catalyst volume), 1.0 h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In order to achieve complete sulphurizing of the catalyst, the H\u003csub\u003e2\u003c/sub\u003eS concentration in the exhaust gas was constantly monitored during the presulfiding process of the catalyst. Complete sulphurizing was reached when the H\u003csub\u003e2\u003c/sub\u003eS concentration in the exhaust gas reached a constant.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Catalyst activity test\u003c/h2\u003e\u003cp\u003eThe catalyst activity tests were performed in a high-pressure autoclave. The experimental conditions were: reaction temperature, 320 ℃, pressure, 4MPa, reaction time, 6h, determination of sulfur and metal content after cooling.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e2.7 Catalyst stability test\u003c/h2\u003e\u003cp\u003eThe catalyst stability test was performed in a 5 mL fixed-bed reactor. The stability test conditions are: reaction temperature, 320 ℃, pressure, 4MPa, liquid hourly space-velocity, 0.5h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, hydrogen-to-hydrocarbon ratio, 600.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results \u0026 discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Textural properties of support\u003c/h2\u003e\u003cp\u003eThe pore size distribution of the support is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The textural properties show that the support prepared has mesoporous structure. The physical properties of the support are: surface area of 133 m\u003csup\u003e2\u003c/sup\u003e/g, pore volume 0.51 mL/g and average pore diameter 15.3 nm.\u003c/p\u003e\u003cp\u003eAdsorption and desorption isotherms of the support are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The isotherms correspond to a type IV, which indicate the presence of mesopores. Based on the IUPAC classification, the hysteresis loop is classified as H2(b), which is associated with complex pore networks formed by particle aggregation. In contrast to H2(a) (ink-bottle pores with narrow neck distributions), H2(b) hysteresis loops arise from broader pore neck width distributions and pore blockage effects in aggregated structures[22\u0026ndash;24]. The filling of the wide pores remains the same as before, but during the desorption stage, the pores remain filled until the adsorbed gas in the narrow pore neck evaporates and empties under lower vapor pressure, allowing the adsorbate in the wide pores to evaporate and desorb. In a pore network structure, the desorption vapor pressure depends on the size and spatial distribution of the pore necks. If the diameter of the pore neck is not too small, the pore network can start to empty at a relative pressure point, which is equivalent to the characteristic permeability threshold.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Properties of feedstock\u003c/h2\u003e\u003cp\u003eThe feedstock for this study was a fraction below 400 ℃ from a coal tar hydrogenation plant. The origin of low temperature coal tar of this factory was from Hami, Xinjiang, China. The physico-chemical properties of the feedstock are given in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFeedstock properties and its metal content\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"13\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eS/ppm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e\u003cp\u003eMental/ppm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCl/ppm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCarbon residue(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDensity(g/cm3)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1918.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e19.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e0.979\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Effect of active components content on HDM and HDS activities\u003c/h2\u003e\u003cp\u003e(1)Catalyst active components loading ratio\u003c/p\u003e\u003cp\u003eIn this study, four catalysts were prepared by equal volume impregnation method using precursors including H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, MoO\u003csub\u003e3\u003c/sub\u003e and Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e \u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO(Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCatalyst active components loading ratio\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComponent/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMoO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNiO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAddition amount of precursor components\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e9.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.48g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.16g MoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.43g Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e \u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10g Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e8.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.74g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.98g MoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.55g Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e \u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10g Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.59g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.77g MoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.21g Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e \u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10g Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e8.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.75g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.04g MoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.43g Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e \u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10g Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e(2)Catalyst activity evaluation\u003c/p\u003e\u003cp\u003eAfter obtaining catalysts with different loading amounts of active components, the catalyst activity was studied in an autoclave by measuring desulfurization and demineralization rates after hydrogenation of the coal tar. Results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe desulfurization rate and demineralization rate after hydrogenation of the coal tar\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDesulfurization rate, %\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e\u003cp\u003eDemetallation rate, %\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMg\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAl\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e58.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e73.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e65.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e73.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e65.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e91.76\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e68.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e83.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e78.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e86.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e91.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e35.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e58.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e33.98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e47.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e59.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e68.96\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e62.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e76.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e66.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e81.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e71.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e94.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe activities of catalysts for demetallation and desulfurization are ranked in decreasing order as C-2\u0026gt;C-4\u0026gt;C-1\u0026gt;C-3. The order of metal removal rates from lowest to highest s as follows: Mg\u0026gt;Na\u0026gt;Al\u0026gt;Ca\u0026gt;Fe. For C-2, although its active metal content is not the highest, it exhibits the best performance of demetallation and desulfurization in all four catalysts prepared, including the removal of Ca and Al, which are difficult to remove[25].During sulfidation, two distinct phases Type I and Type II can form, differing in both the extent of sulfidation and the strength of metal-support interactions[26\u0026ndash;28]. Type I corresponds to incomplete sulfidation and arises when metal-support interactions are strong. Such strong interactions anchor the metal species to the support surface, limiting their migration and reactivity toward sulfidation. As a result, the metal-sulfide slabs exhibit a low stacking degree, exposing fewer catalytically active edge sites and thus diminishing catalytic performance. In contrast, Type II represents complete sulfidation, which typically occurs under weak metal-support interactions. Here, the metal species can migrate freely and undergo full sulfidation, forming highly stacked layered sulfide structures. The increased abundance of exposed active edge sites leads to significantly enhanced catalytic performance. The results indicate that there are more type II Ni-Mo-S active phases on C-2 catalyst compared to other catalysts. From the Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, C-\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e catalyst contains the lowest content of active metals Ni and Mo compared to the other three catalysts despite its high P content. As the result suggests, C-3 provided insufficient catalytic activity of C-3, ultimately leading to lower desulfurization and demetallation rates of coal tar. Mo and P contents in C-2 and C-4 were relatively close, with Ni/Mo content of C-2 catalyst being lower than C-4. However, C-2 exhibited superior catalytic performance, indicating the existence of an optimal value for Ni/Mo.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Effect of active component precursors on HDM and HDS activities\u003c/h2\u003e\u003cp\u003e(1) Catalyst characterization\u003c/p\u003e\u003cp\u003eTo investigate the effect of precursor slection on catalyst activity, C-6, C-7 and C-8 catalysts were prepared with the identical content of active components as with C-2 but using different active precursors. The precursor combinations of the catalysts are shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComposition of active components of catalysts under different precursor conditions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCatalysts\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAddition of precursor components\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.74g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.98gMoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.55gNi(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026nbsp;\u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10gAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.74g H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.98gMoO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.47gNi(OCOCH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026nbsp;\u0026middot; 4H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10gAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.74gH\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.21g(NH\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003eMo\u003csub\u003e7\u003c/sub\u003eO\u003csub\u003e24\u003c/sub\u003e\u0026nbsp;\u0026middot; 4 H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;0.2gPVP\u0026thinsp;+\u0026thinsp;0.55gNi(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026nbsp;\u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10gAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.85gNH\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;1.21g(NH\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003eMo\u003csub\u003e7\u003c/sub\u003eO\u003csub\u003e24\u003c/sub\u003e\u0026nbsp;\u0026middot; 4 H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;5gNH\u003csub\u003e4\u003c/sub\u003eOH\u0026thinsp;+\u0026thinsp;0.55gNi(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026nbsp;\u0026middot; 6H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;10gAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe four catalysts (C-7/C-6/C-2/C-8) were characterized and analyzed by X-ray Photon-electron Spectroscopy. The energy spectrum data of the obtained samples were fitted and analyzed using software XPSPEAK 4.1. The results in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e showed changes in the content of Mo\u003csup\u003e6+\u003c/sup\u003e, Mo\u003csup\u003e5+\u003c/sup\u003e, and Mo\u003csup\u003e4+\u003c/sup\u003e catalysts prepared from different precursors. According to literature reports[29], the binding energies of Mo\u003csup\u003e6+\u003c/sup\u003e, Mo\u003csup\u003e5+\u003c/sup\u003e, and Mo\u003csup\u003e4+\u003c/sup\u003e are approximately 232.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2eV, 230.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2eV, and 228.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2eV, respectively. They are the three common valence states of Mo based catalysts, and all three valence states may exist under reducing conditions. Among them, Mo\u003csup\u003e4+\u003c/sup\u003e is generally believed to be related to the activity of Ni-Mo-S, and the higher its proportion, the better the catalyst activity[29]. Fitting Mo 3d\u003csub\u003e5/2\u003c/sub\u003e spectra in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. by using software gives Mo6+, Mo5+, and Mo4\u0026thinsp;+\u0026thinsp;contents as shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The order of Mo\u003csup\u003e4+\u003c/sup\u003e percentage is C-7\u0026thinsp;\u0026gt;\u0026thinsp;C-6\u0026thinsp;\u0026gt;\u0026thinsp;C-2\u0026thinsp;\u0026gt;\u0026thinsp;C-8. This analysis is further supported by comparison of different Ni forms prepared by different precursors. The order of area size attributed to Ni-Mo-S is C-7\u0026thinsp;\u0026gt;\u0026thinsp;C-6\u0026thinsp;\u0026gt;\u0026thinsp;C-2\u0026thinsp;\u0026gt;\u0026thinsp;C-8.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Mo\u003csup\u003e6+\u003c/sup\u003e, Mo\u003csup\u003e5+\u003c/sup\u003e, Mo\u003csup\u003e4+\u003c/sup\u003e content in catalysts prepared by different precursors\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCatalyst\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eMo\u003csup\u003e6+\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eMo\u003csup\u003e5+\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eMo\u003csup\u003e4+\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eMo\u003csup\u003e4+\u003c/sup\u003e%\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e232.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e42064.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e230.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e8927.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e229.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e25439.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e33.28\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e232.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e44308.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e230.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e13494.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e229.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e31534.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e35.30\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e232.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e43576.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e230.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e8354.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e229.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e30685.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e37.14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e232.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e39665.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e230.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e6955.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e229.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e21352.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e31.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Ni compounds prepared by different precursors\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCatalyst\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eSatellite\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eNi\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eNiMoS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003eNiSx\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBE(e.v)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(Area)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e862.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6809.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e857.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5273.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e856.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4694.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e853.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1449.46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e862.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5952.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e857.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3094.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e856.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e6060.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e853.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1723.68\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e862.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8178\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e857.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2701\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e856.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e6780.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e853.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e2863.83\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e862.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4716.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e857.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5744.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e856.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4381.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e853.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1015.85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eA large number of layered MoS\u003csub\u003e2\u003c/sub\u003e particles with an interplanar spacing of 0.641 nm can be observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e through high-resolution transmission electron microscopy (HRTEM) images. The catalyst generated MoS\u003csub\u003e2\u003c/sub\u003e after presulfurization, which served as the active center for hydrogenation desulfurization. A large number of MoS\u003csub\u003e2\u003c/sub\u003e lattice fringes can be observed in catalysts C-6 and C-7, in a stark contrast to the images of C-2 and C-8. In particular, catalyst C-7 showed not only has more MoS\u003csub\u003e2\u003c/sub\u003e lattice stripes, but also more stacking layers, which could be attributed for its best performance[30]. The PVP dispersant was added during the preparation of C-7 catalyst. The results indicate that the dispersant PVP is beneficial for the dispersion of metals, forming highly dispersed active centers and obtaining the most optimal catalyst performance[31]. C-2 and C-8 samples have fewer MoS\u003csub\u003e2\u003c/sub\u003e stripes, resulting in larger MoS\u003csub\u003e2\u003c/sub\u003e particles and poor metal dispersion. Especially in sample 8, large particles of MoS\u003csub\u003e2\u003c/sub\u003e can be observed, which was the reason for the lower activity of samples 2 and 8.\u003c/p\u003e\u003cp\u003eThere are two Co (Ni) - Mo (W) - S phases in Co (Ni) - Mo (W) sulfide loaded onγ- Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. The type I structures typically consist of a single-layer MoS\u003csub\u003e2\u003c/sub\u003e phase, which strongly interacts with Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e through chemical bonds such as Mo-O-Al and Ni-O-Al. The Type I active phase is not fully sulfided and has less stacking, while the Type II active phase is fully sulfided and highly stacked, with weaker interaction. Due to the strong interaction between the Type I active phase with Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, the Type I active phase usually has better dispersibility. But compared to the Type II active phase, its incomplete sulfurization characteristics endow it with relatively lower HDS activity. The weak interaction between type II active phase with Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, i.e. van der Waals interaction, weakens dispersion but improves the stacking of MoS\u003csub\u003e2\u003c/sub\u003e and leads to complete sulfurization. According to Tops\u0026oslash;e et al. [32], the type II active phase may also exist in the form of a single-layer MoS\u003csub\u003e2\u003c/sub\u003e phase, indicating that high stacking is not a fundamental characteristic of type II active phase. The activity of type II active phase is approximately twice that of type I active phase. The weak interaction with Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e creates more reaction space around the edges of type II active phases, which facilitates the adsorption of large sulfur-containing compounds such as DBT and 4,6-DMDBT, thereby enhancing HDS activity [33\u0026ndash;34].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e(2)Catalyst activity evaluation\u003c/p\u003e\u003cp\u003eThe hydrogenation reaction was conducted at 320\u0026deg;C under a pressure of 4 MPa for a duration of 6 hours. When the temperature inside the autoclave was equilibrated to room temperature, the samples were taken for analyses of sulfur and metal contents. Results were provided in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. The desulfurization rate of the four catalyst studies is ranked in decreasing order as C-7\u0026thinsp;\u0026gt;\u0026thinsp;C-6\u0026thinsp;\u0026gt;\u0026thinsp;C-2\u0026thinsp;\u0026gt;\u0026thinsp;C-8, with desulfurization rates of 84.45%, 73.39%, 68.31%, and 55.66%, respectively. The activity order of demetallation was consistent with that of desulfurization, indicating that hydrogenation desulfurization and hydrogenation demetallation occur at the same active site. The higher the catalyst activity, the higher the activity of hydrogenation desulfurization and hydrogenation demetallation. The results of hydrogenation desulfurization and hydrogenation demetallation were consistent with the XPS characterization of Mo\u003csup\u003e4+\u003c/sup\u003e ratio and Ni-Mo-S ratio, indicating the high likelihood that Ni-Mo-S was the active phase on which hydrogenation desulfurization and hydrogenation demetallation reactions occured. From the HRTEM spectrum in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e., it can be seen that C-6 and C-7 have more Ni-Mo-S active phases, resulting in higher hydrogenation desulfurization and demetallation performance than C-2 and C-8.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe desulfurization rate and demetallation rate of catalysts prepared by different precursors\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCatalyst\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDesulfurization rate, %\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e\u003cp\u003eDemetallation rate, %\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMg\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAl\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e68.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e83.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e78.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e86.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e91.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e73.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e88.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e72.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e90.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e93.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.61\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e84.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e96.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e95.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.90\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e55.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e70.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e63.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e68.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e96.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e90.88\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Catalyst stability\u003c/h2\u003e\u003cp\u003e(1) Fixed-bed continuous-flow micro-reaction equipment\u003c/p\u003e\u003cp\u003eBased on the results from catalyst activity evaluation in autoclave, the optimal catalyst C-7 with the best hydrogenation performance was selected for the fixed bed continuous-flow evaluation. To study its demetallation stability, investigation was conducted on a 5ml fixed bed evaluation device made of stainless steel. The process flow diagram of the fixed bed evaluation device (as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.) mainly includes six unit operations, namely: gas path and its control system, liquid path and its control system, micro fixed bed reactor, gas-liquid separator, liquid receiver, and tail gas measurement and detection system. The reactor has an inner diameter of 8 mm and a length of approximately 40 cm and is made of stainless steel material. The length of the constant temperature zone is about 10 cm. A temperature measuring sleeve is installed inside the reactor, extending from the lower part to the middle of the reactor to accurately measure the reaction temperature.\u003c/p\u003e\u003cp\u003eAfter pressure reduction and stabilization, the hydrogen gas is measured and controlled by a gas mass flow meter to a set value and mixed with the raw oil from the raw oil pump. The raw oil is measured by a high-pressure metering pump and pressurized before being mixed with hydrogen gas into the upper part of the reactor. The raw oil and hydrogen were preheated to the reaction temperature in the preheating furnace placed at the top of the reactor, and then entered the catalyst bed for hydrogenation reaction under isothermal conditions. The oil generated by hydrogenation and excess unreacted hydrogen gas flowed out from the lower part of the reactor, entered the gas-liquid separator through a water-cooled heat exchanger, and the gas was discharged through a gas flow meter.\u003c/p\u003e\u003cp\u003eThis device is equipped with insulation for raw oil tanks, raw oil pumps, raw oil pipelines, production oil pipelines, production oil tanks, etc. The insulation temperature can reach up to 150 ℃ and can be adjusted. It can be used in special situations where the freezing point of raw oil and production oil is higher than the ambient temperature.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003col start=\"2\"\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eCatalyst stability test\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eThe reaction conditions for the catalyst stability test were set as follows: the reaction temperature was 320 ℃, the pressure was 4 MPa, the mass space velocity was 0.5 h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the hydrogen-to-oil volume ratio was 600, and the catalyst loading was 5 mL. Under these conditions, a 168-hour stability test was conducted on the catalyst, with samples collected every 24 hours to analyze sulfur and metal content. Desulfurization and demetallation rates were calculated and provided in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe desulfurization rate and demetallation rate of catalyst C-7 at different reaction times\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eReaction time/h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDesulfurization rate, %\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e\u003cp\u003eDemetallation rate, %\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMg\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAl\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e84.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e96.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e95.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e87.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e94.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e96.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e95.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.32\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e85.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e95.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e95.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e94.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e95.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e84.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e94.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e94.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e94.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e94.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e94.32\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e83.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e96.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e97.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e93.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e97.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e97.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e144\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e85.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e94.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e96.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e96.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e168\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e86.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e94.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e94.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e92.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e94.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e95.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe stability of crude oil processing catalysts is an important parameter. The metal holding capacity and surface coking inhibition ability of catalysts are key factors affecting the stability. The metal sulfides and carbon deposits deposited in the middle of catalyst particles can hinder the effective utilization of catalyst pore volume [35].\u003c/p\u003e\u003cp\u003eFrom the Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the variation of catalyst desulfurization rate with reaction time showed that the desulfurization rate of catalyst C-7 can remain stable at around 85% within the investigated time range, and there was no phenomenon of desulfurization activity degradation. It showed that catalyst C-7 had good removal ability for elements such as Na, Mg, Al, Ca, Fe, etc. The removal rate of these metal was about 95%, and it was stable within 168 hours without any degradation of demetallation performance. The catalyst C-7 had high stability, which was due to the larger pore volume of the prepared catalyst. The larger pore volume can accommodate more metals.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe high activity of catalysts for hydrodemetallation of low-temperature coal tar requires a suitable Ni/Mo. In all synthesized catalysts studied, the highest active metal content in a catalyst did not result in the highest catalytic activity for demetallation and desulfurization. Importantly, the activity pattern of demetallation was observed to be consistent with that of desulfurization, indicating that hydrogenation desulfurization and hydrogenation demetallation may occur at the same active site. C-6 and C-7 have more Type II active phases, resulting in higher hydrogenation desulfurization and demetallation performance than C-2 and C-8. The dispersant PVP is beneficial for the dispersion of metals, forming highly dispersed active centers, thereby increasing the activity of the catalyst. The C-7 catalyst is basically stable within 168 hours and has good removal ability for elements such as Na, Mg, Al, Ca, Fe, etc., with a removal rate of about 95%, without any degradation in the performance of metal removal and desulfurization.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank the technical support from the Coal Chemical Research Institute of China Coal Research Institute Co., Ltd. This work was supported by the National Key Research and Development Program of China (2023YFB4103002).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBowen Ma: Conceptualization, Methodology, Investigation, Writing - Original Draft.\u003c/p\u003e\n\u003cp\u003eJiaqing Song: Supervision, Funding Acquisition, Writing - Review \u0026amp; Editing.\u003c/p\u003e\n\u003cp\u003eYuhui Guo, Yuan Zhao, Bin An: Data Curation, Validation, Experimental Assistance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData and Code Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data supporting the findings of this study are available from the corresponding author (Jiaqing Song) upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSupplementary Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable (this study does not involve human subjects or animal experiments).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003col\u003e\n\u003cli\u003eLi C S, Suzuki K (2010) Resources, properties and utilization of tar. Resour Conserv Recycl 54:905\u0026ndash;915.\u003c/li\u003e\n\u003cli\u003eXie K C, Li W Y, Zhao W (2010) Coal chemical industry and its sustainable development in China. Energy 35:4349\u0026ndash;4355.\u003c/li\u003e\n\u003cli\u003eRosal R, Diez F V, Sastre H (1992) Catalytic-hydrogenation of multiring aromatic-hydrocarbons in a coal-tar fraction. Ind Eng Chem Res 31:1007\u0026ndash;1012.\u003c/li\u003e\n\u003cli\u003eRana M S, S\u0026aacute;mano V, Ancheyta J, D\u0026iacute;az J I (2007) A review of recent advances on process technologies for upgrading of heavy oils and residua. Fuel 86:1216\u0026ndash;1231.\u003c/li\u003e\n\u003cli\u003eFurimsky E, Massoth F E (1999) Catalysis Today. Catal Today 52:381\u0026ndash;389.\u003c/li\u003e\n\u003cli\u003eCastaneda L C, Mu\u0026ntilde;oz J A D, Ancheyta J (2014) Current situation of emerging technologies for upgrading of heavy oils. 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Catal Today 104:86\u0026ndash;93.\u003c/li\u003e\n\u003cli\u003e\u003c/li\u003e\n \u003c/ol\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-mechanical-and-materials-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijme","sideBox":"Learn more about [International Journal of Mechanical and Materials Engineering](http://ijmme.springeropen.com)","snPcode":"40712","submissionUrl":"https://www.editorialmanager.com/ijme/default2.aspx","title":"International Journal of Mechanical and Materials Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"NiMo catalysts, Hydrodemetallation, Low-temperature coal tar, Metals in coal tar","lastPublishedDoi":"10.21203/rs.3.rs-7200385/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7200385/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA variety of catalysts were prepared to investigate the effects of active metals and phosphorous on hydrodemetallation (HDM) and hydrodesulfurization (HDS) of a typical medium-temperature coal tar from Xinjiang in China. A dispersant is used to improve the dispersion of active components on the surface of the support compared with the catalysts without dispersant. The hydrodemetallation products of the autoclave under mild conditions were characterized by inductive coupled plasma emission spectrometer (ICP) and microcoulometer. The difficulty of metal removal is as follows: Mg\u0026gt;Na\u0026gt;Al\u0026gt;Ca\u0026gt;Fe. The combination of H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e,\u003c/p\u003e\u003cp\u003e(NH\u003csub\u003e4\u003c/sub\u003e) \u003csub\u003e6\u003c/sub\u003eMo\u003csub\u003e7\u003c/sub\u003eO\u003csub\u003e24\u003c/sub\u003e\u0026middot;4H\u003csub\u003e2\u003c/sub\u003eO, and Ni(NO\u003csub\u003e3\u003c/sub\u003e) \u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO precursors generated more type II \"Ni-Mo-S\" active phases, with the highest catalytic activity. The dispersant polyvinyl pyrrolidone (PVP) was beneficial for the dispersion of metals, forming highly dispersed active centers, thereby increasing the activity of the catalyst. The hydrogenation desulfurization and hydrogenation demetallation occur at the same active site. The catalyst showed good stability within 168 hours.\u003c/p\u003e","manuscriptTitle":"Catalysts for Demetallation of Low-Temperature Coal Tar","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-07 10:56:19","doi":"10.21203/rs.3.rs-7200385/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2026-01-30T20:48:16+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-08-04T07:01:33+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-04T06:13:34+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"International Journal of Mechanical and Materials Engineering","date":"2025-07-28T06:41:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-25T07:08:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Journal of Mechanical and Materials Engineering","date":"2025-07-23T21:49:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-mechanical-and-materials-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijme","sideBox":"Learn more about [International Journal of Mechanical and Materials Engineering](http://ijmme.springeropen.com)","snPcode":"40712","submissionUrl":"https://www.editorialmanager.com/ijme/default2.aspx","title":"International Journal of Mechanical and Materials Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6c3c6cca-30f1-4b18-9c00-a8efd80b5d9c","owner":[],"postedDate":"August 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T09:51:16+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-07 10:56:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7200385","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7200385","identity":"rs-7200385","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}