Efficient alumina-chromia catalysts with hierarchical porous structure for isobutane dehydrogenation in fixed-bed reactor

Efficient alumina-chromia catalysts with hierarchical porous structure for isobutane dehydrogenation in fixed-bed reactor | 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 Efficient alumina-chromia catalysts with hierarchical porous structure for isobutane dehydrogenation in fixed-bed reactor A. I. Zolotukhina, G. V. Mamontov This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5402041/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract The granulated alumina-chromia (CrO x /Al 2 O 3 ) catalysts for dehydrogenation of light paraffinic hydrocarbons in a fixed-bed reactor are prepared from the products of thermochemical activation of Al(OH) 3 through a one-stage wet mixing method. The role of wood flour addition on the formation of hierarchical porous structure of the catalysts is demonstrated. The high mechanical strength of granules (6.7–10.0 MPa) is achieved despite the presence of macropores in the structure. The role of macropores in the isobutane dehydrogenation under near-real conditions using a bed with the catalyst granules is discussed. The activity rise with the increased addition of wood flour loading and an increase in the amount of macropores is shown. Such data are similar in activity to catalysts used in industry. alumina-chromia catalyst isobutane dehydrogenation fixed-bed reactor wet mixing catalyst granules hierarchical porous structure Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The growing number of applications of polymeric materials leads to an increase in the consumption of olefinic hydrocarbons, which are monomers for the polymerization processes. The main methods to produce the unsaturated hydrocarbons are thermal and catalytic cracking of heavy hydrocarbons [ 1 ] as well as dehydrogenation of the corresponding paraffins [ 2 , 3 ]. The processes of catalytic dehydrogenation of hydrocarbons occupy one of the priority places in the petrochemical industry. This is explained by their involvement in production of the most important monomers for the preparation of synthetic rubbers (butadiene, isobutylene, isoprene, styrene, etc.) through the dehydrogenation of the corresponding C 4 -C 5 saturated hydrocarbons [ 4 ]. Various catalysts have been described for the dehydrogenation of light paraffinic hydrocarbons, including classical materials based on supported noble metals, primarily platinum [ 5 ], chromium oxide catalysts [ 6 ], supported vanadium oxides [ 7 , 8 ] as well as catalysts based on ordered mesoporous supports [ 9 ], organometallic frameworks, [ 10 ], nickel phosphide supported on activated carbon [ 11 ]. However, according to the patent and literature data, the catalysts based on chromium oxide remain the most promising and are used in industry [ 12 – 15 ]. The Russian petrochemical industry mainly uses microspherical alumina-chromium fluidized bed catalysts [ 16 , 17 ], while the dehydrogenation process with fixed catalyst bed is more effective and eco-friendlier due to the higher yield of alkenes and higher selectivity [ 4 ]. The dehydrogenation of paraffin hydrocarbons with a fixed bed of alumina-chromia catalyst ("Catofin" and "Catadiene" processes) are the main processes for the production of unsaturated C 4 hydrocarbons [ 18 – 22 ]. New alternative dehydrogenation processes, including dehydrogenation in membrane reactors [ 23 , 24 ], are discussed in the literature. There are many methods to prepare aluminum-chromium catalysts, including synthesis from metal-organic frameworks [ 25 ], laser activation of α-Cr 2 O 3 [ 26 , 27 ], etc. At the same time, a significant part of the methods can be implemented only under laboratory conditions to obtain small amounts of a catalyst sample. The use of such methods in industry is complicated due to the large number of operations, the complex nature of the support and active component precursors, and high energy costs. For instance, a plasma-chemical method to produce the alumina-chromia catalyst is known, which consists in the heat treatment of the precursors of support and the active component (aluminum powder and chromium carbonyl, respectively) in a low-temperature air plasma flow [ 28 ], however, it is difficult to imagine the use of this approach for the industrial production of the catalysts. The choice of a method to prepare a catalyst is determined by the required characteristics of the final material, including structural and mechanical properties, porous structure, chemical composition, and stability under the conditions of the catalytic process including high temperature and red-ox treatments. The most common and acceptable for the industrial implementation of the synthesis of alumina-chromium catalysts is the impregnation method based on the preparation of a granular alumina support followed by the introduction of active components and modifiers to its surface (Scheme 1 ). The impregnation method is mainly used to synthesize supported catalysts due to its simplicity and efficiency. To prepare the CrO x /Al 2 O 3 catalyst, γ-Al 2 O 3 support granules with a diameter of ~ 3 mm are impregnated with an aqueous solution containing precursors of the active component and modifiers [ 29 – 32 ]. CrO 3 is used as a precursor of the active component in industry due to its high solubility (it allows introducing up to ~ 28% wt. Cr 2 O 3 into the γ-Al 2 O 3 support) and the minimum amount of corrosive gases released during the catalyst calcination as well as the adsorption of chromate ions on the γ-Al 2 O 3 surface leading to a uniform distribution of the active component and its stabilization in a highly dispersed state [ 33 , 34 ]. The main disadvantages of the impregnation method are the possibility of a non-uniform distribution of the active component over the diameter of the granule as well as the use of two heat treatments, which are rather energy intensive. Simplification of the technology to obtain the alumina-chromium catalyst can reduce its cost by reducing energy consumption. An alternative would be a one-step method based on the preparation of catalysts directly from the precursors of support and active component and modifiers by wet mixing followed by extrusion and heat treatment (Scheme 1 ). The production of an alumina-chromia dehydrogenation catalyst by wet mixing involves a one-stage mixing of the support precursor (thermally activated Al(OH) 3 or pseudo-boehmite) with an impregnating solution containing dissolved precursors of the active component and modifiers as well as pore-forming additives. The main advantage of this synthesis is that only one calcination is required, and not two as in the case of the catalyst preparation by the impregnation method. Minimization of the number of calcinations can lead to a significant reduction in the costs to obtain a catalyst. However, a number of questions arise about whether such a one-stage synthesis can ensure the required porous structure of the catalyst, stabilize the active component in the required chemical state, and also have mechanical strength and other operational characteristics of the catalyst granules. Thus, the aim of this study is to develop the alumina-chromia catalysts for the isobutane dehydrogenation to isobutylene using a one-stage, less energy-intensive method of wet mixing of light paraffinic hydrocarbons. The influence of the one-stage approach as well as the role of addition of porogen (wood flour) on the porous structure, mechanical properties, state of chromium and catalytic properties of the prepared alumina-chromia catalysts are discussed. Experimental part Catalysts preparation The thermochemically activated aluminum trihydroxide was used as an alumina precursor. Wood flour was used as a porogen in the amount of 2, 5, and 8%. CrO 3 (chemically pure, Vecton, Russia) and KOH (chemically pure, Vecton, Russia) were used as a precursor of active component and an alkali modifier, respectively. The catalysts were synthesized by mixing alumina precursor with an aqueous solution containing dissolved CrO 3 and KOH. The contents of the components in the catalyst were similar to those in industrial catalysts: 18.5% wt. and 1.5% wt. for Cr 2 O 3 and of K 2 O, respectively [ 30 ]. The components were mixed on a mixer with the z-like blades with a working chamber volume of 1 l until a homogeneous plastic mass was obtained. Additional plasticizers and peptizers (e.g., nitric acid) were not introduced. Then, the resulting mass was molded by extrusion on a laboratory manual extruder, and cylindrical granules with a diameter of ~ 3 mm were obtained. The resulting catalyst was dried at 100 ºС for 4 h and calcined in air at 750°C for 4 h. This method of preparation of an alumina-chromia catalyst is promising and more profitable, since it includes a minimum number of stages and a single calcination, and also allows a more uniform distribution of the active component and modifiers over the entire diameter of the granules. Samples were labelled as CrO x /Al 2 O 3 -x%, where x was the weight percentage of wood flour addition (x = 0, 2, 5, or 8). Catalysts characterization The study of the porous structure of the samples was carried out by the low-temperature (77 K) nitrogen adsorption-desorption on the Tristar 3020 analyzer (Micromeritics, USA). The specific surface area (S BET ) was determined by the multipoint BET method by straightening the nitrogen adsorption isotherm in the range of relative pressures P/P 0 from 0.05 to 0.30; the pore size distribution was obtained using the BJH-Desorption method by analyzing the desorption branch of the nitrogen adsorption-desorption isotherm. The macroporous structure of the catalysts was studied by mercury porosimetry using the Poremaster-33 device (Quantachrome, USA). The textural characteristics of the catalysts were studied using the SEM 515 scanning electron microscope (Philips) with an accelerating voltage of 30 kV. The phase composition of the synthesized catalysts was studied by the X-ray phase diffraction (XRD) analysis using the Shimadzu XRD 6000 diffractometer with CuKα radiation and a Ni filter. The diffraction peaks of the crystalline phases were processed using the POWDER CELL 2.4 software and compared with the peaks of the standard compounds from the PCPDFWIN database. The size of metal oxide crystallites was calculated using the Scherrer equation. The features of the catalyst reduction were studied by the temperature-programmed reduction (TPR) with hydrogen. The experiments were carried out on the ChemiSorb 2750 chemisorption analyzer (Micromeritics, USA) using a 10% H 2 /Ar gas mixture at a flow rate of 20 ml/min and a heating rate of 10 K/min. The strength of the catalyst granules for crushing along the generatrix was measured on the IPG-1 granule strength meter (Russia). The strength was calculated as P = F/(D*h), where F was the granule breaking force (N), D was the granule diameter (2.8-3.0 mm), and h was the granule length (4–7 mm). Measurements were carried out for 30 granules of each of the samples. The catalytic properties of the synthesized catalysts were studied in the isobutane dehydrogenation reaction. The experiments were carried out on the Katakon catalytic flow unit (Katakon, Russia) in a tubular metal reactor with a fixed catalyst bed at temperatures of 570, 590, and 610°C. The experiments were carried out under conditions close to industrial ones, a catalyst granule (diameter was 2.8–3.0 mm, length was 4–7 mm) was used in order to take into account the structural features of the granules on the patterns of the catalytic process in the mixed diffusion-kinetic mode. The reaction mixture comprising 15% i-C 4 H 10 (Ar balance) was fed through the catalytic bed (10 cm 3 of the catalyst granules) at a rate of 25.2 L/h. The experiment was carried out in a cyclic mode: regeneration (atmosphere–air), reduction (H 2 /Ar mixture), and dehydrogenation (isobutane/Ar), sampling for analysis was carried out at the 7th min of dehydrogenation. The reaction mixture and reaction products were analyzed using the Khromos GH-1000 gas chromatograph (Khromos, Russia) equipped with a flame ionization detector (FID) and two micro-katharometers (micro-DTP). Separation of the products was carried out at 50°C using a quartz capillary column with polytrimethylsilylpropine (PTMSP), a packed column with Chromosorb 106 (60/80 mesh), and a packed column with NaX molecular sieves (45/60 mesh). The quantitative calculation of the volume fraction of the components of the gas mixture was determined using the Khromos 2.16.43 software. The main indicators of the catalyst activity, i.e., isobutane conversion (vol %), selectivity towards unsaturated C 4 hydrocarbons (%) were calculated using the following formulas: Isobutane conversion = (C 0 (i-C 4 H 10 ) – C(i-C 4 H 10 ))*100% / C 0 (i-C 4 H 10 ), % Selectivity = C(C 4 H 8 )*100% / (C 0 (i-C 4 H 10 ) – C(i-C 4 H 10 )), % Results and discussion Porous structure and mechanic properties The porous structure of the prepared samples was studied by the low-temperature nitrogen adsorption. Figure 1 shows the N 2 adsorption-desorption isotherms and pore size distribution for catalysts. Table 1 summarizes the textural characteristics. The hysteresis loop on the isotherms in the range of relative pressures of 0.5-1.0 indicates that all catalysts have a mesoporous structure. The pore size distribution (Fig. 1 b) for all samples is in the range from 2 to 20 nm with a distribution maximum of ~ 7 nm. Introduction of 2, 5, or 8%wt. wood flour leads to a shift of the hysteresis on the isotherm in the range of 0.5–1.0 P/P 0 , an increase in the pore volume (Table 1 ) as well as an expansion of the pore size distribution. The specific surface area of the catalysts and the pore volume vary from 68 to 102.2 m 2 /g and from 0.2 to 0.3 cm 3 /g, respectively (Table 1 ). Strength measurements for 30 granules of each of the samples show a decrease in the strength from 10.9 ± 0.5 to 5.2 ± 0.5 MPa, which is associated with an increase in the introduction of the amount of porogen. The catalyst with 8 wt.% of wood flour features a strength of 5.2 MPa. The catalysts with such a low strength cannot be used in the industrial process, hence, this catalyst was neither characterized by all methods nor tested in isobutane dehydrogenation. Table 1 Textural characteristics and properties of the studied samples Catalyst S BET , m 2 /g V pore , cm 3 /g D pore , nm Strength, MPa CrO x /Al 2 O 3 − 0% 68.5 0.20 8.76 10.9 CrO x /Al 2 O 3 − 2% 72 0.21 9.03 10.0 CrO x /Al 2 O 3 − 5% 90.4 0.22 7.59 6.7 CrO x /Al 2 O 3 − 8% 102 0.30 9.21 5.2 Porosimetric measurements of Hg intrusion were carried out to study the macroporous structure of the catalysts with porogen. The differential pore size distribution curves (Fig. 2 a) include two main types of pores, namely, mesopores with a diameter from several nm to ~ 40 nm and wide macropores ranging in size from 50 nm to ~ 8 µm. The presence of macropores is caused by the wood flour. For the sample with the addition of 8%wt. wood flour, an increase in the proportion of pores with sizes of 3–15 µm is observed, which can explain the decrease in the strength of the granules (Table 1 ). Thus, the optimal amount and size of macropores are required for good diffusion inside the granules and keeping of the mechanical strength. Figure 2 b shows the SEM image of wood flour. The flour features fibrous structure with the size of fiber of few micrometers in diameter and a length of 50–500 µm. The addition of this flour into the catalysts mixture during the mixing stage leads to a destruction of large fibers and uniform distribution in homogeneous plastic mass because of high intensity of the mixing in mixer with the z-like blades. According to the SEM results (Fig. 2 c, d), the catalyst synthesized without a blowing agent is characterized by a relatively smooth texture with individual pores with sizes of 2–20 µm. At the same time, the texture of the interpenetrating pores of large and small sizes is typical for the catalysts synthesized with addition of 5%wt. wood flour (Fig. 2 e, f). The shape of some pores is similar to the one of wood fibers (Fig. 2 b), which confirms the role of wood flour addition in the formation of these macropores. XRD and TPR results Figure 3 a shows the XRD patterns for the catalysts. All catalysts have a high content of the amorphous phase (69.4–71.4%, Table 2 ). The support consists of γ-Al 2 O 3 and an amorphous alumina phase. The active component, chromium oxide, is stabilized predominantly in an amorphous state, and only a small part of it (2.9–3.4%wt. from 18.5%wt. of total loading of Cr 2 O 3 ) is in the form of the α-Cr 2 O 3 phase. Table 2 shows that the addition of wood flour does not influence on the phase composition and particle sizes of the phases. Table 2 XRD and TPR data for prepared CrO x /Al 2 O 3 catalysts Catalyst Phases Phase content, % wt. Particle size, nm Н 2 , µmol/g (TPR) Сr (VI), % CrO x /Al 2 O 3 -0% γ-Al 2 O 3 25.1 13.5 519 13.2 α-Cr 2 O 3 3.4 11.9 Amorphous phase 71.5 - CrO x /Al 2 O 3 -2% γ-Al 2 O 3 27.6 10.6 547 13.9 α-Cr 2 O 3 3.0 9.1 Amorphous phase 69.4 - CrO x /Al 2 O 3 -5% γ-Al 2 O 3 25.7 13.2 579 14.7 α-Cr 2 O 3 2.9 9.5 Amorphous phase 71.4 - Figure 3 b shows the TPR profiles for the synthesized catalysts. All catalysts are characterized by the presence of a hydrogen consumption peak in the temperature range from 200 to 450 ° C in the amount of 519–579 µmol/g associated with the Cr (VI) reduction to Cr (III). Thus, it can be concluded that in addition to α-Cr 2 O 3 detected by XRD, the catalysts contain Cr (VI) species in the amount of 13.2–14.7%. The high temperature TPR peak at 500–650 o C can be attributed to the reduction of strongly bonded Cr (VI) species. The amount of these species decreases with the rise of the wood flour content. The areas of the TPR peaks for the studied catalysts are comparable, hence, the pore-forming wood flour additive does not significantly affect the distribution of chromium compounds in the catalyst. A reductive pretreatment of the catalysts prior to the catalytic experiments at 590 o C results in the reduction of Cr (VI) to Cr (III) species [ 35 ]. Catalytic properties Dehydrogenation is a process that is difficult to implement in industry, since thermodynamic equilibrium limits the alkane conversion, the reaction is endothermic and requires a constant supply of heat to the system to maintain the reaction temperature [ 36 ]. The value of the equilibrium degree of conversion during the dehydrogenation of hydrocarbons depends on the temperature. At the same time, to achieve an economically acceptable degree of equilibrium conversion above 50%, the dehydrogenation process requires high temperatures (500–650 o C), at which many side reactions occur, such as thermal cracking, cocking, leading to a decrease in the selectivity of the process and the need to purify the main product from by-products and regenerate the catalyst. The prepared catalyst granules were tested under conditions similar to industrial ones to show the possibility of catalyst application in the process. Figure 4 shows catalytic data for the isobutane dehydrogenation to isobutylene in a fixed-bed reactor. The CrO x /Al 2 O 3 -0% catalyst demonstrates poor activity in comparison with other catalysts despite similar values of surface area and chemical state of chromium. This low activity is attributed mainly to the small amount of macropores in its structure and diffusion limitation inside the catalyst granules. The activity of the catalysts with the addition of 2 or 5%wt. wood flour is significantly higher than the one for the CrO x /Al 2 O 3 -0% catalyst. The increase in the isobutane conversion is observed with a temperature increase from 570°C to 610°C from 60.8 to 68.1%mol. with a respective decrease in the selectivity towards isobutylene from 98.9 to 97.6%mol. for the CrO x /Al 2 O 3 -2% catalyst. The isobutane conversion over CrO x /Al 2 O 3 -5% catalyst is similar, but the selectivity is 94.2–96.0%. It is rather important that the activity and selectivity of these catalysts are similar or higher to those for industrial catalysts (prepared by classical impregnation of alumina support granules). Thus, it was shown that a single-stage wet mixing method using wood flour as a pore-forming additive can be used to obtain the alumina-chromia catalyst with a biporous (hierarchical) structure characterized by the catalytic properties similar to those of catalysts synthesized by impregnation method and used in industry. The presence of macropores with sizes from 50 nm to 5 µm in the catalyst granules provided a decrease in the interdiffusion limitations, which ensured an increase in the catalyst efficiency compared to the sample prepared without the wood flour addition. Сonclusions Alumina-chromia catalysts for the isobutane dehydrogenation to isobutylene in a reactor with a fixed catalyst bed was prepared by a simple wet mixing method. The prepared catalysts met all the stringent requirements for industrial catalysts. The synthesis of the samples was carried out by the wet mixing comprising a one-stage, less energy-consuming and promising method. It was shown that the addition of wood flour made it possible to obtain the catalyst granules with a hierarchical porous structure without affecting the phase composition and distribution of chromia in the catalyst. The catalysts were studied under conditions similar to industrial and showed high catalytic activity comparable to the one of industrial catalysts. Abbreviations S BET - specific surface area determined by the multipoint BET (Brunauer-Emmett-Teller) method; BJH-Desorption method - Barrett-Joyner-Halenda method with using desorption branch of isotherm; SEM – scanning electron microscopy; XRD – X-ray diffraction analysis; TPR – temperature-programmed reduction with H 2 ; FID – flame ionization detector; micro-DTP – micro-katharometers; PTMSP – polytrimethylsilylpropine; V pore – pore volume, measured by N 2 adsorption method; D pore – average pore size, calculated from N 2 adsorption results. Declarations Ethics and Consent to Participate: Not applicable. Consent for Publication: Not Applicable. Competing Interest declaration: The authors have no conflicts of interest to declare that are relevant to the content of this article. Author Contribution: Anastasiya Zolotukhina: Original manuscript writing, Analysis, Interpretation, Data acquisition. Grigory Mamontov: Conception and design, Methodology, Drafting original manuscript and reviewing, Interpretation. Funding: This research was funded by the State assignment of the Ministry of Education and Science of the Russian Federation (project number FSWM-2020-0037). Availability of data and materials: All the data underlying the results are available as a part of the manuscript and no further data is available. Acknowledgments: Authors thanks Tomsk regional center for collective use (Tomsk State University) for SEM studies. References Krylov Н V (2004) Heterogeneous catalysis. IKC Academkniga, Moscow. Weckhuysen B M, Schoonheydt R A (1997) Alkane dehydrogenation over supported chromium oxide catalysts. Catal Today 34: 223-232. https://doi.org/10.1016/S0920-5861(99)00047-4 Shuqi F, Keting Z, Chenguang W, Longlong M, Qi Z, Qiying L, Lungang Ch, Lingpeng Ch, Qiao Zh, Zhipeng T (2009) The properties and catalytic performance of PtSn/Mg(x-Ga)AlO catalysts for ethane dehydrogenation. Chem Eng J 154: 185-188. https://doi.org/10.1039/C7RA00670E Rase H F (2000) Handbook of commercial catalysts. Heterogeneous catalysts, CRC Press. https://doi.org/10.1201/b21367 Long L-L, Lang W-Z, Liu X, Hu C-L, Chu L-F, Guo Y-J (2014) Improved catalytic stability of PtSnIn/xCa–Al catalysts for propane dehydrogenation to propylene. Chem Eng J 257: 209–217. https://doi.org/10.1016/j.cej.2014.07.044 Słoczyński J, Grzybowska B, Kozłowska A, Samson K, Grabowski R, Kotarba A, Hermanowska M (2011) Effect of potassium on physicochemical properties of CrO x /Al 2 O 3 and CrOx/TiO 2 catalysts for oxidative dehydrogenation of isobutane: The role of oxygen chemisorption. Catal Today 169: 29–35. https://doi.org/0.1016/j.cattod.2010.10.096 Yu-Peng T, Peng B, Shao-Min L, Xin-Mei L, Zi-Feng Yan (2016) VO x –K 2 O/γ-Al 2 O 3 catalyst for nonoxidative dehydrogenation of isobutane. Fuel Process Technol 151: 31–39. https://doi.org/10.1016/j.fuproc.2016.05.024 Kharlamova T S, Timofeev K L, Salaev M A, Svetlichnyi V A, Vodyankina O V (2022) Monolayer MgVO x /Al 2 O 3 catalysts for propane oxidative dehydrogenation: Insights into a role of structural, redox, and acid-base properties in catalytic performance. Fuel Process Technol 598: 117574. https://doi.org/10.1016/j.apcata.2020.117574 Shee D, Sayari A (2010) Light alkane dehydrogenation over mesoporous Cr 2 O 3 /Al 2 O 3 catalysts. Appl Catal A 389: 155–164. https://doi.org/10.1016/j.apcata.2010.09.013 Wegrzyniak A, Jarczewski S, Wegrzynowic А, Michorczyk B, Kustrowski Р, Michorczyk Р (2017) Catalytic Behavior of Chromium Oxide Supported on Nanocasting-Prepared Mesoporous Alumina in Dehydrogenation of Propane. Nanomaterials 7: 249. https://doi.org/10.3390/nano7090249 Wolfgang R, Michael J B, Richard Y, Said A (2010) Alkane dehydrogenation catalysts. US Patent 20100312035. Busygin V M, Nesterov O N, Gilmanov Kh Kh, Romanov V G, Lamberov A A, Egorova S R, Bekmukhamedov G E (2015) Catalyst for the dehydrogenation of C 4 -C 5 -paraffin hydrocarbons. RU Patent 2538960. Lamberov A A, Egorova S R (2019) Dehydrogenation catalyst C 4 -C 5 Paraffin hydrocarbons. RU patent 2705808. Gaspar A B, Brito J L, Dieguez L C (2003) Characterization of chromium species in catalysts for dehydrogenation and polymerization. J Mol Cat A: Chem 203:251-266. https://doi.org/10.1016/S1381-1169(03)00381-9 Sainio J, Aronniemi M, Pakarinen O, Kauraala K, Airaksinen S, Krause O, Lahtinen J (2005) An XPS study of CrOx on a thin alumina film and in alumina supported catalysts. Appl Surf Sci 252: 1076-1083. https://doi.org/10.1016/j.apsusc.2005.02.029 Kataev A N, Egorov A G, Egorova S R, Lamberov A A (2015) Mathematical modeling of changes in the fractional composition of dehydrogenation catalysts in a fluidized-bed reactor. Catal Ind 3: 221–226. https://doi.org/10.1134/S2070050415030071 Gilmanov K K, Sakhabutdinov A G, Belanogov I A, Gusamov R R, Gilmullin R R, Sosnovskaya L B (2015) Plantfor dehydrogenation of paraffins orisoparaffins C 3 -C 5 in chromia-alumina catalyst fluidised bed. RU patent 2591159. Sattler J H B, Ruiz-Martinez J, Santillan-Jimenez E, Weckhuysen B M (2014) Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chem Rev 114: 10613–10653. https://doi.org/10.1021/cr5002436 Fattahi M, Kazemeini M, Khorasheh F, Darvishi A, Rashidi A M (2013) Fixed-bed multi-tubular reactors for oxidative dehydrogenation in ethylene process. Chem Eng Technol 36: 1691–1700. https://doi.org/10.1002/ceat.201300148 Darvishi A, Davand R, Khorasheh F, Fattahi M (2016) Modeling-based optimization of fixed-bed industrial reactors for oxidative dehydrogenation of propane (ODHP). Chin J Chem Eng 24: 612–622. https://doi.org/10.1016/j.cjche.2015.12.018 Bugrova T, Tatarkina A, Zhukov I, Mamontov G (2016) Influence of wood flour additive on porous structure and strength properties of moulded alumina. Key Eng Mater 670:139–143. https://doi.org/10.1016/j.arabjc.2020.10.037 Bugrova T A, Mamontov G V (2016) Dehydration of isobutane in fixed bed on the stable to carbon deposition chromia-alumina catalysts. Russ J Appl Chem 89: 1791–1796. https://doi.org/10.1134/S1070427216110094 Erdali A D, Cetinyokus S, Dogan M (2022) Investigation of isobutane dehydrogenation on CrO x /Al 2 O 3 catalyst in a membrane reactor. Chem Eng Process 175: 108904. https://doi.org/10.1016/j.cep.2022.108904 Shelepova E V, Vedyagin A A (2020) Intensification of the dehydrogenation process of different hydrocarbons in a catalytic membrane reactor. Chem Eng Process 155: 108072 https://doi.org/10.1016/j.cep.2020.108072 Zhao H, Song H, Xu L, Chou L (2013) Isobutane dehydrogenation over the mesoporous Cr 2 O 3 /Al 2 O 3 catalysts synthesized from a metal-organic framework MIL-101. Appl Catal A 456:188–196. https://doi.org/10.1016/j.apcata.2013.02.018 Sattler J J H B, Ruiz-Martinez J, Santillan-Jimenez E, Weckhuysen B M (2014) Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chem Rev 114: 10613–10653. https://doi.org/10.1021/cr5002436 Słoczyn´ J, Grzybowska B, Kozłowska A, Samson K, Grabowski R, Kotarba A, Hermanowska M (2011) Effect of potassium on physicochemical properties of CrO x /Al 2 O 3 and CrO x /TiO 2 catalysts for oxidative dehydrogenation of isobutane: The role of oxygen chemisorption. Catal Today 169: 29–35. https://doi.org/ 10.1016/j.cattod.2010.10.096 Balikhin I L, Berestenko V I, Didenko L P, Domashnev I A, Kolesnikova A M, Kurkin E N, Savchenko V I, Torbov V I, Troitskij V N, Shul'ga J M (2009) Plasma chemical method of producing chromia-alumina catalyst for dehydrogenation of hydrocarbons. RU patent 2347613. Fridman V Z, Xing R, Severance M (2016) Investigating the CrO x /Al 2 O 3 dehydrogenation catalyst model: I. identification and stability evaluation of the Cr species on the fresh and equilibrated catalysts. Appl Catal A 523: 39–53. https://doi.org/10.1016/j.apcata.2016.05.008 Fridman V (2012) Catalyst for dehydrogenation of hydrocarbons.US Patent 8101541 Ruettinger W, Jacubinas R (2016) Chromia alumina catalysts for alkane dehydrogenation. US Patent 9254476. Salaeva A A, Salaev M A, Mamontov G V (2020) Effect of Cu modifier on the performance of CrOx/Al 2 O 3 catalysts for isobutane dehydrogenation. Chem Eng Sci 215: 115462. https://doi.org/10.1016/j.ces.2019.115462 Zolotukhina A I, Romanova E V, Bugrova T A, Knyazev A S, Mamontov G V (2020) Influence of impregnation conditions on the activity of CrOx/Al 2 O 3 catalysts in dehydrogenation of isobutane in fixed bed reactor. Arab J Chem 13: 9130-9138. https://doi.org/10.1016/j.arabjc.2020.10.037 Bugrova T A, Dutov V V, Svetlichnyi V A, Cortes C V, Mamontov G V (2019) Oxidative dehydrogenation of ethane with CO 2 over CrOx catalysts supported on Al 2 O 3 , ZrO2, CeO 2 and CexZr 1-x O 2 . Catal Today 333: 71–80. https://doi.org/10.1016/j.cattod.2018.04.047 Bugrova T A, Mamontov G V (2018) Study of CrO X -containing catalysts based on ZrO 2 , CeO2 and Ce X Zr (1-X) O 2 in isobutane dehydrogenation. Kinet Сatal 59: 169-176. https://doi.org/10.1134/S0023158418020027 Shelepova E V, Vedyagin A A (2020) Intensification of the dehydrogenation process of different hydrocarbons in a catalytic membrane reactor. Chem Eng Process 155: 108072. https://doi.org/10.1016/j.cep.2020.108072 Scheme 1 Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files floatimage1.jpeg Scheme 1 The classical and one-stage approach to synthesize CrO x /Al 2 O 3 catalyst Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 28 Jan, 2025 Reviews received at journal 14 Jan, 2025 Reviewers agreed at journal 20 Dec, 2024 Reviews received at journal 29 Nov, 2024 Reviewers agreed at journal 15 Nov, 2024 Reviewers invited by journal 13 Nov, 2024 Editor assigned by journal 10 Nov, 2024 Submission checks completed at journal 10 Nov, 2024 First submitted to journal 06 Nov, 2024 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-5402041","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":378622921,"identity":"e091e981-d85f-42bf-8507-c3d29272d62c","order_by":0,"name":"A. I. Zolotukhina","email":"","orcid":"","institution":"Tomsk State University","correspondingAuthor":false,"prefix":"","firstName":"A.","middleName":"I.","lastName":"Zolotukhina","suffix":""},{"id":378622922,"identity":"d9d8f055-5a89-4c0d-bda9-32a26108843a","order_by":1,"name":"G. V. Mamontov","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBElEQVRIiWNgGAWjYBAC/gbGBiAlwWBwACYCxAce4NEicQCqxRKsJYGBQRLIP5CAR4sBjGEP0wK2Dq8W6cPNLz7usUjcdvx04uPCHzaJm68dfgi05V5iAy4tfIltljOeSSRuO5O72XhGQlritttpBkAtxTi1GJ5hbDPmOQDUciB3mzRPwmFjs9sJIC0JuG2Badlw/i1Ei/Hs9A+EtDQ/Bmu5AbFFzkA6B78tEkBbGGcckDDecOPtZmOetDQ5ids5BQcSDBKMcWnh72F//OHDgTrZDedzNz7msbHh4Z+dvvnDh4oEWVxagIBNAkg4oikwwKYSDpg/AAl7vEpGwSgYBaNgZAMAENFl/vi6C8AAAAAASUVORK5CYII=","orcid":"","institution":"Tomsk State University","correspondingAuthor":true,"prefix":"","firstName":"G.","middleName":"V.","lastName":"Mamontov","suffix":""}],"badges":[],"createdAt":"2024-11-06 10:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5402041/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5402041/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":70003965,"identity":"5a7fb6ad-6e27-487c-920d-df920dc0d4ba","added_by":"auto","created_at":"2024-11-27 12:07:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":337323,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen adsorption-desorption isotherms (a) and corresponding pore size distributions (b) for synthesized catalysts\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/8926061e4139d6eaae00cd07.png"},{"id":70005287,"identity":"c201d287-d24f-4f71-9d10-9a9c629ac7a4","added_by":"auto","created_at":"2024-11-27 12:15:06","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":793677,"visible":true,"origin":"","legend":"\u003cp\u003eDifferential pore size distributions from mercury porosimetry for prepared catalysts (a), SEM images of wood flour (b), CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-0% (c and d) and CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e- 5% (e and f) catalysts.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/a8f7abac0b16bc0523bffb85.png"},{"id":70003967,"identity":"298a7b62-6066-4748-9e94-2ac90a270590","added_by":"auto","created_at":"2024-11-27 12:07:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":347716,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns (a) and temperature-programmed reduction (TPR) profiles (b) for prepared catalysts\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/b410d341592041b421934c58.png"},{"id":70003968,"identity":"21a10854-0cd1-4679-a7ef-db3aa9990d9b","added_by":"auto","created_at":"2024-11-27 12:07:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":198919,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature dependences of isobutane conversion and isobutylene selectivity during isobutane dehydrogenation.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/7c09e76024a980077f321119.png"},{"id":70005680,"identity":"97a744c5-98fb-411c-a3d9-36aa1540b43f","added_by":"auto","created_at":"2024-11-27 12:23:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2253077,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/46223c71-1ca8-4c22-b683-fc94596f26c4.pdf"},{"id":70003969,"identity":"d8e91c18-6f3e-4f9e-b4cf-632e9347fe30","added_by":"auto","created_at":"2024-11-27 12:07:07","extension":"jpeg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":139260,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1\u003c/strong\u003e The classical and one-stage approach to synthesize CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5402041/v1/387c9dba427c1e3029fe55b1.jpeg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Efficient alumina-chromia catalysts with hierarchical porous structure for isobutane dehydrogenation in fixed-bed reactor","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe growing number of applications of polymeric materials leads to an increase in the consumption of olefinic hydrocarbons, which are monomers for the polymerization processes. The main methods to produce the unsaturated hydrocarbons are thermal and catalytic cracking of heavy hydrocarbons [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] as well as dehydrogenation of the corresponding paraffins [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The processes of catalytic dehydrogenation of hydrocarbons occupy one of the priority places in the petrochemical industry. This is explained by their involvement in production of the most important monomers for the preparation of synthetic rubbers (butadiene, isobutylene, isoprene, styrene, etc.) through the dehydrogenation of the corresponding C\u003csub\u003e4\u003c/sub\u003e-C\u003csub\u003e5\u003c/sub\u003e saturated hydrocarbons [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eVarious catalysts have been described for the dehydrogenation of light paraffinic hydrocarbons, including classical materials based on supported noble metals, primarily platinum [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], chromium oxide catalysts [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], supported vanadium oxides [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] as well as catalysts based on ordered mesoporous supports [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], organometallic frameworks, [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], nickel phosphide supported on activated carbon [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, according to the patent and literature data, the catalysts based on chromium oxide remain the most promising and are used in industry [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe Russian petrochemical industry mainly uses microspherical alumina-chromium fluidized bed catalysts [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], while the dehydrogenation process with fixed catalyst bed is more effective and eco-friendlier due to the higher yield of alkenes and higher selectivity [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The dehydrogenation of paraffin hydrocarbons with a fixed bed of alumina-chromia catalyst (\"Catofin\" and \"Catadiene\" processes) are the main processes for the production of unsaturated C\u003csub\u003e4\u003c/sub\u003e hydrocarbons [\u003cspan additionalcitationids=\"CR19 CR20 CR21\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. New alternative dehydrogenation processes, including dehydrogenation in membrane reactors [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], are discussed in the literature.\u003c/p\u003e \u003cp\u003eThere are many methods to prepare aluminum-chromium catalysts, including synthesis from metal-organic frameworks [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], laser activation of α-Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], etc. At the same time, a significant part of the methods can be implemented only under laboratory conditions to obtain small amounts of a catalyst sample. The use of such methods in industry is complicated due to the large number of operations, the complex nature of the support and active component precursors, and high energy costs. For instance, a plasma-chemical method to produce the alumina-chromia catalyst is known, which consists in the heat treatment of the precursors of support and the active component (aluminum powder and chromium carbonyl, respectively) in a low-temperature air plasma flow [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], however, it is difficult to imagine the use of this approach for the industrial production of the catalysts.\u003c/p\u003e \u003cp\u003eThe choice of a method to prepare a catalyst is determined by the required characteristics of the final material, including structural and mechanical properties, porous structure, chemical composition, and stability under the conditions of the catalytic process including high temperature and red-ox treatments. The most common and acceptable for the industrial implementation of the synthesis of alumina-chromium catalysts is the impregnation method based on the preparation of a granular alumina support followed by the introduction of active components and modifiers to its surface (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The impregnation method is mainly used to synthesize supported catalysts due to its simplicity and efficiency. To prepare the CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst, γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support granules with a diameter of ~\u0026thinsp;3 mm are impregnated with an aqueous solution containing precursors of the active component and modifiers [\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. CrO\u003csub\u003e3\u003c/sub\u003e is used as a precursor of the active component in industry due to its high solubility (it allows introducing up to ~\u0026thinsp;28% wt. Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e into the γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support) and the minimum amount of corrosive gases released during the catalyst calcination as well as the adsorption of chromate ions on the γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e surface leading to a uniform distribution of the active component and its stabilization in a highly dispersed state [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The main disadvantages of the impregnation method are the possibility of a non-uniform distribution of the active component over the diameter of the granule as well as the use of two heat treatments, which are rather energy intensive. Simplification of the technology to obtain the alumina-chromium catalyst can reduce its cost by reducing energy consumption.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAn alternative would be a one-step method based on the preparation of catalysts directly from the precursors of support and active component and modifiers by wet mixing followed by extrusion and heat treatment (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The production of an alumina-chromia dehydrogenation catalyst by wet mixing involves a one-stage mixing of the support precursor (thermally activated Al(OH)\u003csub\u003e3\u003c/sub\u003e or pseudo-boehmite) with an impregnating solution containing dissolved precursors of the active component and modifiers as well as pore-forming additives. The main advantage of this synthesis is that only one calcination is required, and not two as in the case of the catalyst preparation by the impregnation method. Minimization of the number of calcinations can lead to a significant reduction in the costs to obtain a catalyst. However, a number of questions arise about whether such a one-stage synthesis can ensure the required porous structure of the catalyst, stabilize the active component in the required chemical state, and also have mechanical strength and other operational characteristics of the catalyst granules.\u003c/p\u003e \u003cp\u003eThus, the aim of this study is to develop the alumina-chromia catalysts for the isobutane dehydrogenation to isobutylene using a one-stage, less energy-intensive method of wet mixing of light paraffinic hydrocarbons. The influence of the one-stage approach as well as the role of addition of porogen (wood flour) on the porous structure, mechanical properties, state of chromium and catalytic properties of the prepared alumina-chromia catalysts are discussed.\u003c/p\u003e"},{"header":"Experimental part","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCatalysts preparation\u003c/h2\u003e \u003cp\u003eThe thermochemically activated aluminum trihydroxide was used as an alumina precursor. Wood flour was used as a porogen in the amount of 2, 5, and 8%. CrO\u003csub\u003e3\u003c/sub\u003e (chemically pure, Vecton, Russia) and KOH (chemically pure, Vecton, Russia) were used as a precursor of active component and an alkali modifier, respectively. The catalysts were synthesized by mixing alumina precursor with an aqueous solution containing dissolved CrO\u003csub\u003e3\u003c/sub\u003e and KOH. The contents of the components in the catalyst were similar to those in industrial catalysts: 18.5% wt. and 1.5% wt. for Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and of K\u003csub\u003e2\u003c/sub\u003eO, respectively [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The components were mixed on a mixer with the z-like blades with a working chamber volume of 1 \u003cem\u003el\u003c/em\u003e until a homogeneous plastic mass was obtained. Additional plasticizers and peptizers (e.g., nitric acid) were not introduced.\u003c/p\u003e \u003cp\u003eThen, the resulting mass was molded by extrusion on a laboratory manual extruder, and cylindrical granules with a diameter of ~ 3 mm were obtained. The resulting catalyst was dried at 100 ºС for 4 h and calcined in air at 750°C for 4 h. This method of preparation of an alumina-chromia catalyst is promising and more profitable, since it includes a minimum number of stages and a single calcination, and also allows a more uniform distribution of the active component and modifiers over the entire diameter of the granules. Samples were labelled as CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-x%, where x was the weight percentage of wood flour addition (x = 0, 2, 5, or 8).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCatalysts characterization\u003c/h3\u003e\n\u003cp\u003eThe study of the porous structure of the samples was carried out by the low-temperature (77 K) nitrogen adsorption-desorption on the Tristar 3020 analyzer (Micromeritics, USA). The specific surface area (S\u003csub\u003eBET\u003c/sub\u003e) was determined by the multipoint BET method by straightening the nitrogen adsorption isotherm in the range of relative pressures P/P\u003csub\u003e0\u003c/sub\u003e from 0.05 to 0.30; the pore size distribution was obtained using the BJH-Desorption method by analyzing the desorption branch of the nitrogen adsorption-desorption isotherm.\u003c/p\u003e \u003cp\u003eThe macroporous structure of the catalysts was studied by mercury porosimetry using the Poremaster-33 device (Quantachrome, USA). The textural characteristics of the catalysts were studied using the SEM 515 scanning electron microscope (Philips) with an accelerating voltage of 30 kV. The phase composition of the synthesized catalysts was studied by the X-ray phase diffraction (XRD) analysis using the Shimadzu XRD 6000 diffractometer with CuKα radiation and a Ni filter. The diffraction peaks of the crystalline phases were processed using the POWDER CELL 2.4 software and compared with the peaks of the standard compounds from the PCPDFWIN database. The size of metal oxide crystallites was calculated using the Scherrer equation.\u003c/p\u003e \u003cp\u003eThe features of the catalyst reduction were studied by the temperature-programmed reduction (TPR) with hydrogen. The experiments were carried out on the ChemiSorb 2750 chemisorption analyzer (Micromeritics, USA) using a 10% H\u003csub\u003e2\u003c/sub\u003e/Ar gas mixture at a flow rate of 20 ml/min and a heating rate of 10 K/min.\u003c/p\u003e \u003cp\u003eThe strength of the catalyst granules for crushing along the generatrix was measured on the IPG-1 granule strength meter (Russia). The strength was calculated as P = F/(D*h), where F was the granule breaking force (N), D was the granule diameter (2.8-3.0 mm), and h was the granule length (4–7 mm). Measurements were carried out for 30 granules of each of the samples.\u003c/p\u003e \u003cp\u003eThe catalytic properties of the synthesized catalysts were studied in the isobutane dehydrogenation reaction. The experiments were carried out on the Katakon catalytic flow unit (Katakon, Russia) in a tubular metal reactor with a fixed catalyst bed at temperatures of 570, 590, and 610°C. The experiments were carried out under conditions close to industrial ones, a catalyst granule (diameter was 2.8–3.0 mm, length was 4–7 mm) was used in order to take into account the structural features of the granules on the patterns of the catalytic process in the mixed diffusion-kinetic mode. The reaction mixture comprising 15% i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e (Ar balance) was fed through the catalytic bed (10 cm\u003csup\u003e3\u003c/sup\u003e of the catalyst granules) at a rate of 25.2 L/h. The experiment was carried out in a cyclic mode: regeneration (atmosphere–air), reduction (H\u003csub\u003e2\u003c/sub\u003e/Ar mixture), and dehydrogenation (isobutane/Ar), sampling for analysis was carried out at the 7th min of dehydrogenation. The reaction mixture and reaction products were analyzed using the Khromos GH-1000 gas chromatograph (Khromos, Russia) equipped with a flame ionization detector (FID) and two micro-katharometers (micro-DTP). Separation of the products was carried out at 50°C using a quartz capillary column with polytrimethylsilylpropine (PTMSP), a packed column with Chromosorb 106 (60/80 mesh), and a packed column with NaX molecular sieves (45/60 mesh). The quantitative calculation of the volume fraction of the components of the gas mixture was determined using the Khromos 2.16.43 software.\u003c/p\u003e \u003cp\u003eThe main indicators of the catalyst activity, i.e., isobutane conversion (vol %), selectivity towards unsaturated C\u003csub\u003e4\u003c/sub\u003e hydrocarbons (%) were calculated using the following formulas:\u003c/p\u003e \u003cp\u003eIsobutane conversion = (C\u003csub\u003e0\u003c/sub\u003e(i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e) – C(i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e))*100% / C\u003csub\u003e0\u003c/sub\u003e(i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e), %\u003c/p\u003e \u003cp\u003eSelectivity = C(C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003e)*100% / (C\u003csub\u003e0\u003c/sub\u003e(i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e) – C(i-C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003e)), %\u003c/p\u003e\n\n"},{"header":"Results and discussion","content":"\u003ch2\u003ePorous structure and mechanic properties\u003c/h2\u003e\u003cp\u003eThe porous structure of the prepared samples was studied by the low-temperature nitrogen adsorption. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms and pore size distribution for catalysts. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the textural characteristics. The hysteresis loop on the isotherms in the range of relative pressures of 0.5-1.0 indicates that all catalysts have a mesoporous structure. The pore size distribution (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb) for all samples is in the range from 2 to 20 nm with a distribution maximum of ~ 7 nm. Introduction of 2, 5, or 8%wt. wood flour leads to a shift of the hysteresis on the isotherm in the range of 0.5–1.0 P/P\u003csub\u003e0\u003c/sub\u003e, an increase in the pore volume (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) as well as an expansion of the pore size distribution. The specific surface area of the catalysts and the pore volume vary from 68 to 102.2 m\u003csup\u003e2\u003c/sup\u003e/g and from 0.2 to 0.3 cm\u003csup\u003e3\u003c/sup\u003e/g, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Strength measurements for 30 granules of each of the samples show a decrease in the strength from 10.9 ± 0.5 to 5.2 ± 0.5 MPa, which is associated with an increase in the introduction of the amount of porogen. The catalyst with 8 wt.% of wood flour features a strength of 5.2 MPa. The catalysts with such a low strength cannot be used in the industrial process, hence, this catalyst was neither characterized by all methods nor tested in isobutane dehydrogenation.\u003c/p\u003e\u003cdiv class=\"gridtable\"\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=\"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\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\u003eTextural characteristics and properties of the studied samples\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCatalyst\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eS\u003csub\u003eBET\u003c/sub\u003e, m\u003csup\u003e2\u003c/sup\u003e/g\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eV\u003csub\u003epore\u003c/sub\u003e, cm\u003csup\u003e3\u003c/sup\u003e/g\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eD\u003csub\u003epore\u003c/sub\u003e, nm\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eStrength, MPa\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e − 0%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.76\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.9\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e − 2%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.03\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e − 5%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e90.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.59\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.7\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e − 8%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e102\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003ePorosimetric measurements of Hg intrusion were carried out to study the macroporous structure of the catalysts with porogen. The differential pore size distribution curves (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea) include two main types of pores, namely, mesopores with a diameter from several nm to ~ 40 nm and wide macropores ranging in size from 50 nm to ~ 8 µm. The presence of macropores is caused by the wood flour. For the sample with the addition of 8%wt. wood flour, an increase in the proportion of pores with sizes of 3–15 µm is observed, which can explain the decrease in the strength of the granules (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Thus, the optimal amount and size of macropores are required for good diffusion inside the granules and keeping of the mechanical strength.\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb shows the SEM image of wood flour. The flour features fibrous structure with the size of fiber of few micrometers in diameter and a length of 50–500 µm. The addition of this flour into the catalysts mixture during the mixing stage leads to a destruction of large fibers and uniform distribution in homogeneous plastic mass because of high intensity of the mixing in mixer with the z-like blades. According to the SEM results (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, d), the catalyst synthesized without a blowing agent is characterized by a relatively smooth texture with individual pores with sizes of 2–20 µm. At the same time, the texture of the interpenetrating pores of large and small sizes is typical for the catalysts synthesized with addition of 5%wt. wood flour (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, f). The shape of some pores is similar to the one of wood fibers (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb), which confirms the role of wood flour addition in the formation of these macropores.\u003c/p\u003e\u003ch3\u003eXRD and TPR results\u003c/h3\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea shows the XRD patterns for the catalysts. All catalysts have a high content of the amorphous phase (69.4–71.4%, Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The support consists of γ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and an amorphous alumina phase. The active component, chromium oxide, is stabilized predominantly in an amorphous state, and only a small part of it (2.9–3.4%wt. from 18.5%wt. of total loading of Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) is in the form of the α-Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e phase. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows that the addition of wood flour does not influence on the phase composition and particle sizes of the phases.\u003c/p\u003e\u003cdiv class=\"gridtable\"\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=\"char\" char=\".\" 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=\"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\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\u003eXRD and TPR data for prepared CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCatalyst\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePhases\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase\u003c/p\u003e \u003cp\u003econtent, % wt.\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParticle\u003c/p\u003e \u003cp\u003esize, nm\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eН\u003csub\u003e2\u003c/sub\u003e, µmol/g\u003c/p\u003e \u003cp\u003e(TPR)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eСr (VI), %\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-0%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eγ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e519\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e13.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eα-Cr\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eO\u003c/b\u003e\u003csub\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e3.4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11.9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAmorphous phase\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e71.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-2%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eγ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e27.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e547\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e13.9\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eα-Cr\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eO\u003c/b\u003e\u003csub\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e3.0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e9.1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAmorphous phase\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e69.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-5%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eγ-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e579\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e14.7\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eα-Cr\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eO\u003c/b\u003e\u003csub\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e2.9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e9.5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAmorphous phase\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e71.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb shows the TPR profiles for the synthesized catalysts. All catalysts are characterized by the presence of a hydrogen consumption peak in the temperature range from 200 to 450 ° C in the amount of 519–579 µmol/g associated with the Cr (VI) reduction to Cr (III). Thus, it can be concluded that in addition to α-Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e detected by XRD, the catalysts contain Cr (VI) species in the amount of 13.2–14.7%. The high temperature TPR peak at 500–650 \u003csup\u003eo\u003c/sup\u003eC can be attributed to the reduction of strongly bonded Cr (VI) species. The amount of these species decreases with the rise of the wood flour content. The areas of the TPR peaks for the studied catalysts are comparable, hence, the pore-forming wood flour additive does not significantly affect the distribution of chromium compounds in the catalyst. A reductive pretreatment of the catalysts prior to the catalytic experiments at 590 \u003csup\u003eo\u003c/sup\u003eC results in the reduction of Cr (VI) to Cr (III) species [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e\u003ch2\u003eCatalytic properties\u003c/h2\u003e\u003cp\u003eDehydrogenation is a process that is difficult to implement in industry, since thermodynamic equilibrium limits the alkane conversion, the reaction is endothermic and requires a constant supply of heat to the system to maintain the reaction temperature [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The value of the equilibrium degree of conversion during the dehydrogenation of hydrocarbons depends on the temperature. At the same time, to achieve an economically acceptable degree of equilibrium conversion above 50%, the dehydrogenation process requires high temperatures (500–650 \u003csup\u003eo\u003c/sup\u003eC), at which many side reactions occur, such as thermal cracking, cocking, leading to a decrease in the selectivity of the process and the need to purify the main product from by-products and regenerate the catalyst.\u003c/p\u003e\u003cp\u003eThe prepared catalyst granules were tested under conditions similar to industrial ones to show the possibility of catalyst application in the process. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows catalytic data for the isobutane dehydrogenation to isobutylene in a fixed-bed reactor. The CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-0% catalyst demonstrates poor activity in comparison with other catalysts despite similar values of surface area and chemical state of chromium. This low activity is attributed mainly to the small amount of macropores in its structure and diffusion limitation inside the catalyst granules.\u003c/p\u003e\u003cp\u003eThe activity of the catalysts with the addition of 2 or 5%wt. wood flour is significantly higher than the one for the CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-0% catalyst. The increase in the isobutane conversion is observed with a temperature increase from 570°C to 610°C from 60.8 to 68.1%mol. with a respective decrease in the selectivity towards isobutylene from 98.9 to 97.6%mol. for the CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-2% catalyst. The isobutane conversion over CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-5% catalyst is similar, but the selectivity is 94.2–96.0%. It is rather important that the activity and selectivity of these catalysts are similar or higher to those for industrial catalysts (prepared by classical impregnation of alumina support granules).\u003c/p\u003e\u003cp\u003eThus, it was shown that a single-stage wet mixing method using wood flour as a pore-forming additive can be used to obtain the alumina-chromia catalyst with a biporous (hierarchical) structure characterized by the catalytic properties similar to those of catalysts synthesized by impregnation method and used in industry. The presence of macropores with sizes from 50 nm to 5 µm in the catalyst granules provided a decrease in the interdiffusion limitations, which ensured an increase in the catalyst efficiency compared to the sample prepared without the wood flour addition.\u003c/p\u003e"},{"header":"Сonclusions","content":"\u003cp\u003eAlumina-chromia catalysts for the isobutane dehydrogenation to isobutylene in a reactor with a fixed catalyst bed was prepared by a simple wet mixing method. The prepared catalysts met all the stringent requirements for industrial catalysts. The synthesis of the samples was carried out by the wet mixing comprising a one-stage, less energy-consuming and promising method. It was shown that the addition of wood flour made it possible to obtain the catalyst granules with a hierarchical porous structure without affecting the phase composition and distribution of chromia in the catalyst. The catalysts were studied under conditions similar to industrial and showed high catalytic activity comparable to the one of industrial catalysts.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eS\u003csub\u003eBET\u003c/sub\u003e\u003c/strong\u003e - specific surface area determined by the multipoint \u003cstrong\u003eBET\u003c/strong\u003e (Brunauer-Emmett-Teller) method;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBJH-Desorption method\u003c/strong\u003e - Barrett-Joyner-Halenda method with using desorption branch of isotherm;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSEM\u003c/strong\u003e \u0026ndash; scanning electron microscopy;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eXRD\u003c/strong\u003e \u0026ndash; X-ray diffraction analysis;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTPR\u003c/strong\u003e \u003cstrong\u003e\u0026ndash;\u003c/strong\u003e temperature-programmed reduction with H\u003csub\u003e2\u003c/sub\u003e;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFID\u003c/strong\u003e \u003cstrong\u003e\u0026ndash;\u0026nbsp;\u003c/strong\u003eflame ionization detector;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003emicro-DTP\u003c/strong\u003e \u0026ndash; micro-katharometers;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePTMSP \u0026ndash;\u0026nbsp;\u003c/strong\u003epolytrimethylsilylpropine;\u003c/p\u003e\n\u003cp\u003eV\u003csub\u003epore\u003c/sub\u003e \u0026ndash; pore volume, measured by N\u003csub\u003e2\u003c/sub\u003e adsorption method;\u003c/p\u003e\n\u003cp\u003eD\u003csub\u003epore\u003c/sub\u003e \u0026ndash; average pore size, calculated from N\u003csub\u003e2\u003c/sub\u003e adsorption results.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics and Consent to Participate:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication:\u003c/strong\u003e Not Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interest declaration:\u003c/strong\u003e The authors have no conflicts of interest to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAnastasiya Zolotukhina:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eOriginal manuscript writing, Analysis, Interpretation, Data acquisition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGrigory Mamontov:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eConception and design, Methodology, Drafting original manuscript and reviewing, Interpretation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This research was funded by the State assignment of the Ministry of Education and Science of the Russian Federation (project number FSWM-2020-0037).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u003c/strong\u003e All the data underlying the results are available as a part of the manuscript and no further data is available.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u0026nbsp;\u003c/strong\u003eAuthors thanks\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eTomsk regional center for collective use (Tomsk State University) for SEM studies.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKrylov Н V (2004) Heterogeneous catalysis. IKC Academkniga, Moscow.\u003c/li\u003e\n\u003cli\u003eWeckhuysen B M, Schoonheydt R A (1997) Alkane dehydrogenation over supported chromium oxide catalysts. Catal Today 34: 223-232. https://doi.org/10.1016/S0920-5861(99)00047-4\u003c/li\u003e\n\u003cli\u003eShuqi F, Keting Z, Chenguang W, Longlong M, Qi Z, Qiying L, Lungang Ch, Lingpeng Ch, Qiao Zh, Zhipeng T (2009) The properties and catalytic performance of PtSn/Mg(x-Ga)AlO catalysts for ethane dehydrogenation. Chem Eng J 154: 185-188. https://doi.org/10.1039/C7RA00670E\u003c/li\u003e\n\u003cli\u003eRase H F (2000) Handbook of commercial catalysts. Heterogeneous catalysts, CRC Press. https://doi.org/10.1201/b21367\u003c/li\u003e\n\u003cli\u003eLong L-L, Lang W-Z, Liu X, Hu C-L, Chu L-F, Guo Y-J (2014) Improved catalytic stability of PtSnIn/xCa\u0026ndash;Al catalysts for propane dehydrogenation to propylene. Chem Eng J 257: 209\u0026ndash;217. https://doi.org/10.1016/j.cej.2014.07.044\u003c/li\u003e\n\u003cli\u003eSłoczyński J, Grzybowska B, Kozłowska A, Samson K, Grabowski R, Kotarba A, Hermanowska M (2011) Effect of potassium on physicochemical properties of CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and CrOx/TiO\u003csub\u003e2\u003c/sub\u003e catalysts for oxidative dehydrogenation of isobutane: The role of oxygen chemisorption. Catal Today 169: 29\u0026ndash;35. https://doi.org/0.1016/j.cattod.2010.10.096 \u003c/li\u003e\n\u003cli\u003eYu-Peng T, Peng B, Shao-Min L, Xin-Mei L, Zi-Feng Yan (2016) VO\u003csub\u003ex\u003c/sub\u003e\u0026ndash;K\u003csub\u003e2\u003c/sub\u003eO/\u0026gamma;-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst for nonoxidative dehydrogenation of isobutane. Fuel Process Technol 151: 31\u0026ndash;39. https://doi.org/10.1016/j.fuproc.2016.05.024 \u003c/li\u003e\n\u003cli\u003eKharlamova T S, Timofeev K L, Salaev M A, Svetlichnyi V A, Vodyankina O V (2022) Monolayer MgVO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts for propane oxidative dehydrogenation: Insights into a role of structural, redox, and acid-base properties in catalytic performance. Fuel Process Technol 598: 117574. https://doi.org/10.1016/j.apcata.2020.117574\u003c/li\u003e\n\u003cli\u003eShee D, Sayari A (2010) Light alkane dehydrogenation over mesoporous Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts. Appl Catal A 389: 155\u0026ndash;164. https://doi.org/10.1016/j.apcata.2010.09.013\u003c/li\u003e\n\u003cli\u003eWegrzyniak A, Jarczewski S, Wegrzynowic А, Michorczyk B, Kustrowski Р, Michorczyk Р (2017) Catalytic Behavior of Chromium Oxide Supported on Nanocasting-Prepared Mesoporous Alumina in Dehydrogenation of Propane. Nanomaterials 7: 249. https://doi.org/10.3390/nano7090249 \u003c/li\u003e\n\u003cli\u003eWolfgang R, Michael J B, Richard Y, Said A (2010) Alkane dehydrogenation catalysts. US Patent 20100312035.\u003c/li\u003e\n\u003cli\u003eBusygin V M, Nesterov O N, Gilmanov Kh Kh, Romanov V G, Lamberov A A, Egorova S R, Bekmukhamedov G E (2015) Catalyst for the dehydrogenation of C\u003csub\u003e4\u003c/sub\u003e-C\u003csub\u003e5\u003c/sub\u003e-paraffin hydrocarbons. RU Patent 2538960.\u003c/li\u003e\n\u003cli\u003eLamberov A A, Egorova S R (2019) Dehydrogenation catalyst C\u003csub\u003e4\u003c/sub\u003e-C\u003csub\u003e5\u003c/sub\u003e Paraffin hydrocarbons. RU patent 2705808.\u003c/li\u003e\n\u003cli\u003eGaspar A B, Brito J L, Dieguez L C (2003) Characterization of chromium species in catalysts for dehydrogenation and polymerization. J Mol Cat A: Chem 203:251-266. https://doi.org/10.1016/S1381-1169(03)00381-9 \u003c/li\u003e\n\u003cli\u003eSainio J, Aronniemi M, Pakarinen O, Kauraala K, Airaksinen S, Krause O, Lahtinen J (2005) An XPS study of CrOx on a thin alumina film and in alumina supported catalysts. Appl Surf Sci 252: 1076-1083. https://doi.org/10.1016/j.apsusc.2005.02.029 \u003c/li\u003e\n\u003cli\u003eKataev A N, Egorov A G, Egorova S R, Lamberov A A (2015) Mathematical modeling of changes in the fractional composition of dehydrogenation catalysts in a fluidized-bed reactor. Catal Ind 3: 221\u0026ndash;226. https://doi.org/10.1134/S2070050415030071 \u003c/li\u003e\n\u003cli\u003eGilmanov K K, Sakhabutdinov A G, Belanogov I A, Gusamov R R, Gilmullin R R, Sosnovskaya L B (2015) Plantfor dehydrogenation of paraffins orisoparaffins C\u003csub\u003e3\u003c/sub\u003e -C\u003csub\u003e5\u003c/sub\u003e in chromia-alumina catalyst fluidised bed. RU patent 2591159.\u003c/li\u003e\n\u003cli\u003eSattler J H B, Ruiz-Martinez J, Santillan-Jimenez E, Weckhuysen B M (2014) Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chem Rev 114: 10613\u0026ndash;10653. https://doi.org/10.1021/cr5002436 \u003c/li\u003e\n\u003cli\u003eFattahi M, Kazemeini M, Khorasheh F, Darvishi A, Rashidi A M (2013) Fixed-bed multi-tubular reactors for oxidative dehydrogenation in ethylene process. Chem Eng Technol 36: 1691\u0026ndash;1700. https://doi.org/10.1002/ceat.201300148\u003c/li\u003e\n\u003cli\u003eDarvishi A, Davand R, Khorasheh F, Fattahi M (2016) Modeling-based optimization of fixed-bed industrial reactors for oxidative dehydrogenation of propane (ODHP). Chin J Chem Eng 24: 612\u0026ndash;622. https://doi.org/10.1016/j.cjche.2015.12.018\u003c/li\u003e\n\u003cli\u003eBugrova T, Tatarkina A, Zhukov I, Mamontov G (2016) Influence of wood flour additive on porous structure and strength properties of moulded alumina. Key Eng Mater 670:139\u0026ndash;143. https://doi.org/10.1016/j.arabjc.2020.10.037\u003c/li\u003e\n\u003cli\u003eBugrova T A, Mamontov G V (2016) Dehydration of isobutane in fixed bed on the stable to carbon deposition chromia-alumina catalysts. Russ J Appl Chem 89: 1791\u0026ndash;1796. https://doi.org/10.1134/S1070427216110094\u003c/li\u003e\n\u003cli\u003eErdali A D, Cetinyokus S, Dogan M (2022) Investigation of isobutane dehydrogenation on CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst in a membrane reactor. Chem Eng Process 175: 108904. https://doi.org/10.1016/j.cep.2022.108904 \u003c/li\u003e\n\u003cli\u003eShelepova E V, Vedyagin A A (2020) Intensification of the dehydrogenation process of different hydrocarbons in a catalytic membrane reactor. Chem Eng Process 155: 108072 https://doi.org/10.1016/j.cep.2020.108072\u003c/li\u003e\n\u003cli\u003eZhao H, Song H, Xu L, Chou L (2013) Isobutane dehydrogenation over the mesoporous Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts synthesized from a metal-organic framework MIL-101. Appl Catal A 456:188\u0026ndash;196. https://doi.org/10.1016/j.apcata.2013.02.018 \u003c/li\u003e\n\u003cli\u003eSattler J J H B, Ruiz-Martinez J, Santillan-Jimenez E, Weckhuysen B M (2014) Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chem Rev 114: 10613\u0026ndash;10653. https://doi.org/10.1021/cr5002436\u003c/li\u003e\n\u003cli\u003eSłoczyn\u0026acute; J, Grzybowska B, Kozłowska A, Samson K, Grabowski R, Kotarba A, Hermanowska M (2011) Effect of potassium on physicochemical properties of CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and CrO\u003csub\u003ex\u003c/sub\u003e/TiO\u003csub\u003e2\u003c/sub\u003e catalysts for oxidative dehydrogenation of isobutane: The role of oxygen chemisorption. Catal Today 169: 29\u0026ndash;35. https://doi.org/ 10.1016/j.cattod.2010.10.096\u003c/li\u003e\n\u003cli\u003eBalikhin I L, Berestenko V I, Didenko L P, Domashnev I A, Kolesnikova A M, Kurkin E N, Savchenko V I, Torbov V I, Troitskij V N, Shul\u0026apos;ga J M (2009) Plasma chemical method of producing chromia-alumina catalyst for dehydrogenation of hydrocarbons. RU patent 2347613.\u003c/li\u003e\n\u003cli\u003eFridman V Z, Xing R, Severance M (2016) Investigating the CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e dehydrogenation catalyst model: I. identification and stability evaluation of the Cr species on the fresh and equilibrated catalysts. Appl Catal A 523: 39\u0026ndash;53. https://doi.org/10.1016/j.apcata.2016.05.008\u003c/li\u003e\n\u003cli\u003eFridman V (2012) Catalyst for dehydrogenation of hydrocarbons.US Patent 8101541 \u003c/li\u003e\n\u003cli\u003eRuettinger W, Jacubinas R (2016) Chromia alumina catalysts for alkane dehydrogenation. US Patent 9254476.\u003c/li\u003e\n\u003cli\u003eSalaeva A A, Salaev M A, Mamontov G V (2020) Effect of Cu modifier on the performance of CrOx/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts for isobutane dehydrogenation. Chem Eng Sci 215: 115462. https://doi.org/10.1016/j.ces.2019.115462\u003c/li\u003e\n\u003cli\u003eZolotukhina A I, Romanova E V, Bugrova T A, Knyazev A S, Mamontov G V (2020) Influence of impregnation conditions on the activity of CrOx/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts in dehydrogenation of isobutane in fixed bed reactor. Arab J Chem 13: 9130-9138. https://doi.org/10.1016/j.arabjc.2020.10.037 \u003c/li\u003e\n\u003cli\u003eBugrova T A, Dutov V V, Svetlichnyi V A, Cortes C V, Mamontov G V (2019) Oxidative dehydrogenation of ethane with CO\u003csub\u003e2\u003c/sub\u003e over CrOx catalysts supported on Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, ZrO2, CeO\u003csub\u003e2\u003c/sub\u003e and CexZr\u003csub\u003e1-x\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e. Catal Today 333: 71\u0026ndash;80. https://doi.org/10.1016/j.cattod.2018.04.047\u003c/li\u003e\n\u003cli\u003eBugrova T A, Mamontov G V (2018) Study of CrO\u003csub\u003eX\u003c/sub\u003e-containing catalysts based on ZrO\u003csub\u003e2\u003c/sub\u003e, CeO2 and Ce\u003csub\u003eX\u003c/sub\u003eZr\u003csub\u003e(1-X) \u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e in isobutane dehydrogenation. Kinet Сatal 59: 169-176. https://doi.org/10.1134/S0023158418020027 \u003c/li\u003e\n\u003cli\u003eShelepova E V, Vedyagin A A (2020) Intensification of the dehydrogenation process of different hydrocarbons in a catalytic membrane reactor. Chem Eng Process 155: 108072. https://doi.org/10.1016/j.cep.2020.108072\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme 1","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\u003e\n"}],"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":"catalysis-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Catalysis Letters](https://link.springer.com/journal/10562)","snPcode":"10562","submissionUrl":"https://submission.springernature.com/new-submission/10562/3","title":"Catalysis Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"alumina-chromia catalyst, isobutane dehydrogenation, fixed-bed reactor, wet mixing, catalyst granules, hierarchical porous structure","lastPublishedDoi":"10.21203/rs.3.rs-5402041/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5402041/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe granulated alumina-chromia (CrO\u003csub\u003ex\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) catalysts for dehydrogenation of light paraffinic hydrocarbons in a fixed-bed reactor are prepared from the products of thermochemical activation of Al(OH)\u003csub\u003e3\u003c/sub\u003e through a one-stage wet mixing method. The role of wood flour addition on the formation of hierarchical porous structure of the catalysts is demonstrated. The high mechanical strength of granules (6.7\u0026ndash;10.0 MPa) is achieved despite the presence of macropores in the structure. The role of macropores in the isobutane dehydrogenation under near-real conditions using a bed with the catalyst granules is discussed. The activity rise with the increased addition of wood flour loading and an increase in the amount of macropores is shown. Such data are similar in activity to catalysts used in industry.\u003c/p\u003e","manuscriptTitle":"Efficient alumina-chromia catalysts with hierarchical porous structure for isobutane dehydrogenation in fixed-bed reactor","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-27 12:07:02","doi":"10.21203/rs.3.rs-5402041/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-28T20:52:33+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-14T13:34:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"91609685716282922864194651279755679458","date":"2024-12-20T16:22:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-29T15:49:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"13041441151182701599352540498801733691","date":"2024-11-15T14:14:29+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-13T20:42:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-11-10T23:39:54+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-11-10T23:38:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Catalysis Letters","date":"2024-11-06T10:38:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"catalysis-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Catalysis Letters](https://link.springer.com/journal/10562)","snPcode":"10562","submissionUrl":"https://submission.springernature.com/new-submission/10562/3","title":"Catalysis Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"30ad7b52-aa46-4622-b20d-0ac8bfe1b927","owner":[],"postedDate":"November 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-07-17T18:38:11+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-27 12:07:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5402041","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5402041","identity":"rs-5402041","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}