Constant flow oxygen generation with manganese oxide supported on spherical activated carbon using hydrogen peroxide decomposition

Constant flow oxygen generation with manganese oxide supported on spherical activated carbon using hydrogen peroxide decomposition | 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 Constant flow oxygen generation with manganese oxide supported on spherical activated carbon using hydrogen peroxide decomposition Jae-Hoon Lee, Eun-Hee Park, Jae-Hong Shin, Deog-Su Park, Dong-Won Lee, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7060294/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract In situations where oxygen is scarce or absent, such as during prolonged diving or high-altitude mountaineering, or in cases where breathing becomes impossible due to toxic substances like in fires or chemical, biological, or radiological incidents, a device that supplies a specific amount of oxygen is necessary for survival. A Manganese Oxide/Spherical Activated Carbon (Mn-SPAC) catalyst was produced for the purpose of creating a steady oxygen supply. This was achieved through the carbonization and activation of manganese-exchanged resin under nitrogen and steam conditions. The characteristics of Mn-SPAC were analyzed using pore characteristics analysis, XRD, FE-SEM, and XPS, focusing on the amount of added manganese and carbonization time. To optimize conditions for generating a consistent amount of oxygen, the synthesized catalyst was reacted with 30% hydrogen peroxide, and the amount of oxygen produced was measured. In the optimized reaction setup, a consistent oxygen release was monitored for a duration of 20 minutes during the decomposition of hydrogen peroxide. Comparative XPS studies conducted pre- and post-reaction demonstrated the oxidation state of manganese following the process. These observations indicate that the newly developed catalyst is best suited for one-time use scenarios. Spherical activated carbon Hydrogen peroxide Manganese Catalyst Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Oxygen is the most fundamental substance required for maintaining our bodies, and it needs to be supplied continuously, anytime and anywhere. While breathing is possible through air in normal environments, survival becomes impossible in situations where oxygen is scarce, or absent, such as during diving or high-altitude mountaineering, or in cases where breathing is hindered by toxic substances, as in fires or chemical, biological, radiological, and nuclear (CBRN) incidents. To survive in these environments, technology that can supply the necessary oxygen for breathing over a certain period is essential. There are several approaches to providing oxygen for predetermined time: high-pressure compressed oxygen, electrochemical generation, and chemical production methods [ 1 ]. The high-pressure compressed oxygen technique stores oxygen gas in high-pressure vessels but carries explosion risks from physical impacts or heat exposure [ 2 ]. While electrochemical generation offers stable oxygen supply by decomposing water, its reliance on external power sources restricts its use [ 3 , 4 ]. Chemical oxygen generation, which produces oxygen through compound decomposition or reactions, is a one-off. For situations requiring sustained oxygen supply, the chemical method was considered optimal, prompting further investigation. The most common chemical methods for oxygen generation involve using potassium superoxide or hydrogen peroxide. KO 2 is highly reactive and can produce oxygen when it comes into contact with water or carbon dioxide [ 5 ]. Human breath, which contains 100% relative humidity and 4.5% CO 2 , is enough to trigger this reaction. However, KO 2 must be manufactured and stored in airtight conditions, making maintenance challenging. Hydrogen peroxide, on the other hand, is a powerful oxidizer used in rocket propulsion. Yet, concentrations below 35% are non-flammable, allowing for safer oxygen production. While hydrogen peroxide naturally breaks down into water and oxygen, this process is slow. Catalysts are used to speed up the decompositions [ 6 ]. Common metal catalysts include Au, Fe, Cu, and Mn. Manganese (Mn) is particularly versatile due to its wide range of oxidation states (0 to + 7) found in nature, making it a stable and flexible option [ 7 ]. Typically, during the hydrogen peroxide decomposition reaction, as the concentration of hydrogen peroxide decreases, the rate of oxygen generation should gradually decrease. However, in the case of manganese, the generation rate can be easily controlled. Oxidized manganese produces not only oxygen but also superoxide as an intermediate product during hydrogen peroxide decomposition, resulting in a gradual increase in the rate of oxygen evolution. This means that manganese with low oxidation states exhibits active oxygen generation initially, while manganese with high oxidation states shows gradually increasing oxygen generation over time [ 8 ]. We synthesized a catalyst with manganese oxide doped on the surface of activated carbon to produce a constant amount of oxygen. This was achieved by exchanging manganese on an ion exchange resin and then appropriately adjusting the carbonization and activation time. Activated carbon itself is also a material that can decompose hydrogen peroxide, and during the activation process, the specific surface area of the activated carbon increases, as does the oxidation degree of manganese. The initial manganese product in the activation process is MnS. By optimizing the activation time and the amount of Mn precursor, we synthesized a mixture of MnO and Mn 3 0 4 , resulting in a catalyst that generates oxygen at a constant rate. 2. Experimental 2.1 Materials The following are the reagents and substances used for the experiment. Strong acid cation exchange resin (Dow Chemical, AMBERLITE™ IRC 120 H), and manganese nitrate hydrate (Mn(NO 3 ) 2 ·xH 2 O, 98%, Sigma-Aldrich) were used for sample preparation. Also, hydrogen peroxide solution (H 2 O 2 , 30%, OCI) was used for the catalyst activity test. 2.2 Synthesis of Mn-SPAC(Spherical Activated Carbon) catalyst The preparation steps of Mn-SPAC are as follows. A desired concentration of precursor solution ((0.05 N, 0.1 N, 0.2 N) was made by dissolving a quantity of Mn(NO 3 ) 2 ·xH 2 O into 200 mL of distilled water. A strong acid cation resin (Dow Chemical) is then introduced and stirred sufficiently for ion exchange to take place. The mixture will be dried in an oven at 100°C for over 12 hours after being washed and filtered. The dried sample will then be set up in a quartz reactor, as seen in Fig. 1, and the temperature is steadily increased at a rate of 5°C/min until it reaches 900°C under a nitrogen atmosphere. Steam is then introduced into the apparatus when the temperature reaches 900°C to begin the activation process. The time of injection was adjusted o 2.5, 5, 7.5, and 10.0 hours to control the activation time. 2.3 Characterizations 2.3.1. Pore characteristic analysis N2 adsorption isotherm measurements of activated carbon were performed using a volumetric adsorption apparatus (Tristar, Micromeritics). The specific surface area was calculated using the Brunauer-Emmett-Teller (BET) equation. A measured value of P/P0 = 0.99 was used to determine the total pore volume. All sample analyses were conducted after treating the samples at 350°C under vacuum for more than 3 hours. 2.3.2. XRD An Ultima IV Diffractometer (Rigaku) was used for X-ray diffraction analysis to examine the crystallite structure of metal within the activated carbon. The scan speed was 5°/min, with a scan range of 5–80°. Cu-Kα (λ = 1.5418Å) was used as the light source. 2.3.3. SEM-EDS In order to observe the shapes of the activated carbon samples, Scanning Electron Microscope (SEM) images were taken using Mira 3 LMU FEG (Tescan). Additionally, Energy Dispersive X-ray Spectrometer (EDS) analysis was carried out using a Quantax 200 EDS (Bruker) to identify the Mn content in the activated carbon. 2.3.4. XPS The XPS experiment was performed using a monochromatic AlKα source on an ESCALAB 250 (VG Scientific, USA) at the Converging Materials Research Center, Dong-eui University (Busan, South Korea). 2.3.5 Comparison of hydrogen peroxide decomposition activity The decomposition of hydrogen peroxide was conducted in a 500 mL glass reactor. To evaluate the performance differences of the samples according to various preparation conditions, 0.05 g of each sample was introduced to 200 mL of 30% hydrogen peroxide. Additionally, the samples were introduced until the amount of manganese reached a predetermined amount (7.2 mg) in order to observe the performance differences dependent on pore characteristics and manganese crystal structure when the quantity of manganese in the reaction is equal. The amount of Mn in the catalysts was also fixed to observe how the characteristics of pores and crystal structures affect the performance of the catalyst during the reaction. 200 mL of a 30% hydrogen peroxide solution was used for the reaction. A given amount of catalyst was put in the catalyst container. Then, the container was dropped into the hydrogen peroxide solution after the reactor is sealed to initiate the reaction. Using an oxygen analyzer (Rapidox 1100-EF, Cambridge Sensotec), 99.9% of the gas produced during the reaction was confirmed as oxygen. The flow rate of oxygen was measured every 30 seconds using a mass flow meter, and this measurement was also an indication of hydrogen peroxide decomposition. As all produced gas passed through a moisture trap, the flow rate was measured by using a mass flow meter. Figure 2 presents a schematic diagram of the apparatus. 3. Results and discussion 3.1. Characterization of Mn-SPAC The value of manganese content in the final samples measured by using BET, SEM-EDS analysis are found in Table 1 . Table 1 Physical properties of all samples Precursor conc. (N) Activation time (h) Sample Name Mn content a (wt%) S BET b (m 2 /g) V meso c (cm 3 /g) V micro d (cm 3 /g) 0.05 2.5 Mn-SPAC 1–1 1.00 860 0.15 (34%) 0.30 (66%) 5 Mn-SPAC 1–2 1.43 1250 0.31 (43%) 0.42 (57%) 7.5 Mn-SPAC 1–3 2.51 1630 0.74 (64%) 0.42 (36%) 10 Mn-SPAC 1–4 5.99 2040 1.46 (83%) 0.29 (17%) 0.1 2.5 Mn-SPAC 2 − 1 2.00 820 0.22 (45%) 0.27 (55%) 5 Mn-SPAC 2–2 3.84 1330 0.78 (69%) 0.35 (31%) 7.5 Mn-SPAC 2–3 8.57 1680 1.33 (82%) 0.30 (18%) 10 Mn-SPAC 2–4 12.21 1610 1.36 (88%) 0.19 (12%) 0.2 2.5 Mn-SPAC 3 − 1 3.35 760 0.17 (40%) 0.25 (60%) 5 Mn-SPAC 3 − 2 7.31 1220 0.79 (72%) 0.31 (28%) 7.5 Mn-SPAC 3–3 14.37 1350 1.08 (80%) 0.27 (20%) 10 Mn-SPAC 3–4 18.22 1140 1.00 (81%) 0.23 (19%) a: Manganese content by EDS results b: BET specific surface area c: Mesopore volume d: Micropore volume ( ): Percentage of mesopore volume and micropore volume As seen in Table 1 , the amount of Mn in the samples increased as the activation time increased from 2.5 h to 10 h when the precursor concentrations stayed constant. The Mn content for the sample with 0.05 N of precursor increased from 1.00 wt% (Mn-SPAC 1–1) to 5.99 wt% (Mn-SPAC 1–4), which was approximately a 5 wt% increase. As for the 0.1 N sample, the Mn amount increased from 1.00 wt% (Mn-SPAC 2 − 1) to 12.21 wt% (Mn-SPAC 2–4), showing approximately a 10 wt% increase. The Sample with 0.2N had an increase of 15 wt% where the Mn content rose from 3.35 wt% (Mn-SPAC 3 − 1) to 18.22 wt% (Mn-SPAC 3–4). Furthermore, Fig. 3 shows sample images obtained using SEM. Samples with a precursor concentration of 0.05 N with activation time between 2.5 ~ 7.5 h maintained a spherical shape (Figs. 3 (a), 3(b) and 3(c)). However, the samples with activation time greater than 10 hours were disfigured and cracked, and did not retain the spherical shape (Fig. 3 (d)). This was a common phenomenon for all samples. In the case of samples with cracks, it was relatively difficult to recover the catalyst after reaction [ 9 ]. Thus, it was decided that samples with activation time greater than 10 hours are unsuitable for the actual process. Table 1 shows the values of specific surface area, mesopore volume, and micropore volume of samples using N 2 adsorption isotherm measurements. As shown in Fig. 4 , all samples prepared with 0.05 N of precursor had increasing specific surface area as the activation time increased. However, the growth of specific surface area stopped and decreased when the activation time was greater than 10 hours for the samples prepared with precursor concentrations of 0.1 N and 0.2 N. This could be explained by the amount of manganese shown from the EDS results. The quantity of activated carbon diminished in the same amount of samples with an increase of metal. Since metal is a non-porous material, when the amount of metal exceeds a certain amount, the specific surface area decreases. The amounts of Mn in samples with precursor concentrations of 0.1 N and 0.2 N were 12.21wt% (Mn-SPAC2-4) and 18.22wt% (Mn-SPAC3-4) respectively, and 2 ~ 3 times greater than 0.05 N. It was found that the specific surface area of these samples decreased. Total pore volume is considered as the sum of mesopore volume and micropore volume. Percentages of mesopore and micropore volume to total pore volume were indicated in parentheses next to the pore volume values. There was an increase in the percentage of mesopore volume in relation to the total pore volume as the activation time increased in all the samples. Over-activation caused several nearby micropores to break down and to reform into mesopores. Therefore, the mesopore volume increased as the activation time increased [ 10 , 11 ]. Figure 5 shows the results of the manganese structure by the precursor concentration from the XRD analysis. It explained how the manganese structure from the activation process affects the decomposition of hydrogen peroxide. Mn-SPAC 1–1 did not form any structure, whereas Mn-SPAC 1–2 and 1–3 had both MnS and MnO structure peaks. On the other hand, Mn-SPAC 1–4 only showed a MnO structure peak (Fig. 5 (a)). Mn-SPAC 2 − 1 showed no peak, like that of Mn-SPAC 1–1, whereas Mn-SPAC 2–2 only had a MnS peak. Mn-SPAC 2–3 had both MnS and MnO peaks, and Mn-SPAC 2–4 had both MnO and Mn 3 O 4 peaks (Fig. 5 (b)). Mn-SPAC 3 − 1 had a MnS peak, even though it had the same sample and activation time as Mn-SPAC 1–1 and Mn-SPAC 2 − 1, which were amorphous. Mn-SPAC 3 − 2 had MnS, MnO, and Mn 3 O 4 peaks, whereas Mn-SPAC 3–3 and Mn-SPAC 3–4 had MnO and Mn 3 O 4 peaks (Fig. 5 (c)). XRD analysis results showed three types of crystal structures exist in samples as follows: MnS, MnO, and Mn 3 O 4 . These results along with preparation conditions are found in Table 2 . According to the order of appearance of different peaks according to activation time, it can be seen that manganese initially formed MnS by bonding with sulfur in sulfonic acid. As the activation time increased, sulfur reacted with oxygen in the steam to become SOx and was eliminated. Manganese also oxidized and bonded with oxygen, then became MnO and Mn 3 O 4 . Meanwhile, the typical crystallite changes in manganese oxide are shown in Fig. 6 [ 12 ]. In general, the changes in manganese oxide crystallite follow a path of increasing oxidation state of manganese, which was confirmed by the XRD analysis. Figure 5 shows that as higher the concentration of precursor increased, the oxidation rate of manganese increased, more quickly producing a MnO or Mn 3 O 4 . Table 2 Crystallite phases of all samples by XRD results Sample name Precursor conc. (N) Activation time (h) Crystallite phase Mn-SPAC 1–1 0.05 2.5 - - - Mn-SPAC 1–2 5 MnS MnO - Mn-SPAC 1–3 7.5 MnS MnO - Mn-SPAC 1–4 10 - MnO - Mn-SPAC 2 − 1 0.1 2.5 - - - Mn-SPAC 2–2 5 MnS - - Mn-SPAC 2–3 7.5 MnS MnO - Mn-SPAC 2–4 10 - MnO Mn 3 O 4 Mn-SPAC 3 − 1 0.2 2.5 MnS - - Mn-SPAC 3 − 2 5 MnS MnO Mn 3 O 4 Mn-SPAC 3–3 7.5 - MnO Mn 3 O 4 Mn-SPAC 3–4 10 - MnO Mn 3 O 4 3.2 Comparison of hydrogen peroxide decomposition activity by samples with different activation time All sample amounts were fixed at 0.05 g for the experiment. Figure 6 (A) shows the results from the hydrogen peroxide decomposition experiment that used samples with 0.05 N of precursor concentration. Mn-SPAC 1–1 and Mn-SPAC 1–3 had an increasing hydrogen peroxide decomposition activity proportional to Mn content, but it decreased with sample Mn-SPAC 1–4. Despite the increase in specific surface area, it was suspected that the performance decreased due to the difference in the crystal structure of manganese. This can be deduced from Table 2 and Fig. 5 . As seen in Mn-SPAC 1–1, hydrogen peroxide decomposition was rarely observed with samples that were void of a manganese crystal structure. Because the overall Mn amount was low, samples with a precursor concentration of 0.05 N only had below 0.2 L/min production of oxygen regardless of the activation time, which led to the early completion of the experiment. Figure 6 (B) shows the results of hydrogen peroxide decomposition for samples with a precursor concentration of 0.1 N. Both Mn-SPAC 2 − 1 and Mn-SPAC 1–1 showed no manganese crystals and no activity in decomposing hydrogen peroxide. Mn-SPAC 2–2, 2–3, and 2–4, which contained either MnS and MnO, MnO, or Mn 3 O 4 , exhibited improved activity, producing more than 0.2L/min of oxygen over a prolonged period. The Mn-SPAC 2–3 sample exhibited a faint rise in oxygen release about 4 minutes after the initiation of the hydrogen peroxide decomposition reaction. This results from partial manganese oxidation during catalyst activation [ 13 ]. For Mn-SPAC 2–4, higher manganese content sped up the overall reaction. Yet, the larger proportion of highly oxidized manganese caused a slower rise in oxygen production after the 4-minute mark compared to Mn-SPAC 2–3. This feature was also observed with 0.2N precursor concentration samples (Fig. 6 (C)). The oxygen flow rates for Mn-SPAC 3 − 1 and Mn-SPAC 3 − 2 display an immediate decreasing trend. Conversely, Mn-SPAC 3–3 maintains a steady oxygen flow until a decline is observed after 20 minutes. This decrease is attributed to the fact that the reduction in oxygen production rate, resulting from the depletion of hydrogen peroxide, outweighs the oxygen flow enhancement effect induced by superoxide [ 14 ]. For Mn-SPAC 3–4, the exceptionally high oxidation state of Mn leads to a very slow increase in oxygen flow. This characteristic is particularly evident when measurements are performed with a constant Mn content in the catalyst (as illustrated in Fig. 6 (D)). Inter alia, Mn-SPAC 3–3 produced the most linear flat pattern in terms of oxygen production and maintained a long production time. Also, the total flow of oxygen calculated using mensuration by parts satisfied the theoretical oxygen production, which was approximately 22 L (Eq. 1) that could be generated from 200 mL of 30% hydrogen peroxide solution. This showed that the sample had sufficient activity during the reaction. This means the decomposition was almost complete. Therefore, the amount of manganese contained in 0.05 g of the Mn-SPAC 3–3 sample, 7.2 mg, was determined as a fixed reaction input. 3.3 Catalytic analysis after hydrogen peroxide decomposition reaction Changes in the catalyst after hydrogen peroxide reaction were confirmed through XRD and XPS analysis. After the hydrogen peroxide reaction, Mn 3 O 4 and Mn 2 O 3 crystal structures are observed in Mn-SPAC due to oxidation reactions (Fig. 7 ). XPS analysis also shows that manganese oxidation occurred (Fig. 8 ). In the case of C1s in XPS, when comparing before (i) and after (ii) the reaction, an increase in the intensity of C-O ((i) 285.43 eV, (ii) 285.20 eV) and C = O ((i) 287.34 eV, (ii) 287.69 eV) can be observed due to hydration and oxidation of activated carbon. For O1s, the intensity of C-O ((i) 531.83 eV, (ii) 531. 85 eV) and C = O ((i) 532.92 eV, (II) 533.03 eV) increased due to hydration of activated carbon, and the intensity of Mn-O ((i) 530.69 eV, (ii) 530.85 eV) increased due to manganese oxidation. In the case of Mn2p, an increase in the intensity of Mn 3+ ((i) 643.20 eV, (ii) 643.30 eV) and Mn 4+ ((i) 644.90 eV, (ii) 644.80 eV). This is consistent with existing research reports related to manganese phase changes during hydrogen peroxide decompositon reaction. During hydrogen peroxide decomposition, manganese undergoes oxidation reactions in the presence of oxygen gas [ 15 ]. Another report states that when oxidized manganese is placed in an aqueous solution, the catalyst surface is hydrated to form Mn(OH) 2 [ 16 ]. Mn(OH) 2 continuously undergoes decomposition reaction in hydrogen peroxide solution, gradually oxidizing the manganese surface [ 17 ]. Based on these results, we can anticipate that when the Mn-loaded catalyst is reused after recovery, due to its oxidation, the oxygen output will not be constant but will gradually increase. Therefore, this catalyst can be used as an one-off catalyst. 4. Conclusion This research focused on developing a catalyst capable of steady oxygen evolution. The process involved ion-exchanging manganese onto a resin substrate, followed by controlled carbonization and activation procedures. This method resulted in the doping of manganese oxides onto the activated carbon surface. During activation, MnS formed initially. Through optimization of activation duration and Mn precursor concentration, a composite of MnO and Mn 3 0 4 was synthesized, yielding a catalyst exhibiting constant-rate oxygen generation. We implemented a reproducible manufacturing technology for a catalyst shape and formulation that can control the amount of oxygen generated rapidly at the initial stage of the decomposition reaction of hydrogen peroxide, which is an oxygen-generating medium, and continuously generate a constant amount of oxygen until the end of the decomposition reaction as the hydrogen peroxide is depleted. This is anticipated to enhance the technology for sustained oxygen production and delivery, enabling simpler operations to safeguard lives during emergencies and oxygen-deficient conditions resulting from diverse natural calamities and catastrophes like earthquakes and structural fires. Declarations Acknowledgement This work was supported by the Technology development Program (240002213) funded by the Ministry of SMEs and Startups grant (MSS, Korea). In addition, this research has been performed as a project No KK2411-30 (Development of economical low-carbon hydrogen production and storage technology from low-value carbon resources) supported by the Korea Research Institute of Chemical Technology (KRICT). References Suneel Kumar, Manoj Goswami, Smriti Mishra, Netrapal Singh, Hafsa Siddiqui, Satendra Kumar, N Sathisha,b, Mohammad Akram Khana,b, Surender kumara, & Avanish Kumar SrivastavaIndian, Journal of Pure & Applied Physics 59 (2021) 477. FIRE AND EXPLOSION HAZARDS CAUSED BY OXYGEN CYLINDERS, Safety and Security Engineering VII (2018) 141. Yu Zhang, Ke Xie, Fangyao Zhou, Feiteng Wang, Qian Xu, Jun Hu, Honghe Ding, Peng Li, Yi Tan, Deming Li, Junfa Zhu, Huang Zhou, Changming Zhao, Sen Lin, and Yuen Wu, Adv. Energy Mater. 12 (2022) 2201027. J. Dingley, D. 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Kyubin Shim, Kyeong-Deok Seo, and Hae Jin Kim, Adv. Funct. Mater. 33 (2023) 2210549. Hiroki Tamura,1 Kenya Mita, Akio Tanaka, Makoto Ito, Adv. Journal of Colloid and Interface Science 243 (2001) 202. Moses Wekesa and Yonghao Ni, The Canadian Journal of Chemical Engineering 81 (2003) 968. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 13 Jul, 2025 Reviewers invited by journal 13 Jul, 2025 Editor assigned by journal 09 Jul, 2025 First submitted to journal 06 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-7060294","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":484653595,"identity":"780b564f-4512-4ebf-8049-2fd58db78865","order_by":0,"name":"Jae-Hoon Lee","email":"","orcid":"","institution":"Pusan NU: Pusan National University","correspondingAuthor":false,"prefix":"","firstName":"Jae-Hoon","middleName":"","lastName":"Lee","suffix":""},{"id":484653596,"identity":"3eeba33b-e552-4bba-9ab9-ef38b9ce9659","order_by":1,"name":"Eun-Hee Park","email":"","orcid":"","institution":"KRICT: Korea Research Institute of Chemical 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Hong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1UlEQVRIiWNgGAWjYBACxgYeEGVjwMAMFZEgUksaSAtjA1FaGBjAWg4bgLUTpYW5/+zBxwW/zhubtzM/f8C4x4ZBcvYBAg6bkZdsPLPvtpnMYTbDBoZnaQzSfAmEtPCYSfP23LaRYOYBOuzAYQY5HgIOY+w/A9JyDqblPxFaGnLMpHl+HDCDajnAIE1Qy4wcY2PehmRjCWY2wxkJB5J5JHsIaDHsP2P4mOePneEM/sMPPnw4YCcncYaQlgaQVW1QXgI0mvACeTD5h6C6UTAKRsEoGMkAAOMSOR946vRQAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-6391-127X","institution":"Korea Research Institute of Chemical Technology","correspondingAuthor":true,"prefix":"","firstName":"Yeon","middleName":"Soo","lastName":"Hong","suffix":""}],"badges":[],"createdAt":"2025-07-07 01:25:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7060294/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7060294/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87032749,"identity":"2d30c1d4-9e6f-4e5a-9be7-59642e775f0c","added_by":"auto","created_at":"2025-07-18 13:01:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":43203,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic diagram of the activation reactor.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/b8e0ab71cd83a9cca6f48fa1.png"},{"id":87034415,"identity":"6fb49642-5082-4209-9b0a-0a680bc03a34","added_by":"auto","created_at":"2025-07-18 13:09:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":80137,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eExperiment apparatus for decomposition of hydrogen peroxide.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/b0ba674effea2bf62150921e.png"},{"id":87035747,"identity":"d90aca80-22a9-4ae1-9fe0-b73a9f1ae6e1","added_by":"auto","created_at":"2025-07-18 13:17:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":479676,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM images of samples ((a): Mn-SPAC 1-1, (b): Mn-SPAC 1-2, (c): Mn-SPAC 1-3, (d): Mn-SPAC 1-4, (e): Mn-SPAC 2-1, (f): Mn-SPAC 2-2, (g): Mn-SPAC 2-3, (h): Mn-SPAC 2-4, (i): Mn-SPAC 3-1, (j): Mn-SPAC 3-2, (k): Mn-SPAC 3-3, (l): Mn-SPAC 3-4).\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/c3345318cf1eca3c4720424a.png"},{"id":87032750,"identity":"e25c8606-a6a8-470f-a422-11886370c707","added_by":"auto","created_at":"2025-07-18 13:01:20","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":28281,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSpecific area of samples in relation to activation time.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/e34b5372a95304a5c8dff0f6.png"},{"id":87032754,"identity":"f5a13ada-0bca-4336-a5e7-c90a1418ac65","added_by":"auto","created_at":"2025-07-18 13:01:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":195876,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eResults of XRD pattern by samples (a): Samples with precursor concentration 0.05N, (b): Samples with precursor concentration 0.1N, (c): Samples with precursor concentration 0.2N.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/2afdc2448973aab118d2a793.png"},{"id":87032755,"identity":"76ba7779-ee34-411a-b4a8-0dc8ac996447","added_by":"auto","created_at":"2025-07-18 13:01:21","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":129793,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eActivity test result for hydrogen peroxide decomposition with Precursor concentration ((A) 0.05 N. (B) 0.1 N, (C) 0.2 N) and (D) constant manganese (7.2 mg).\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/270d53e02410640598c6fd6b.png"},{"id":87034418,"identity":"1fd9ab8f-115a-4a23-8837-e3e245fb2032","added_by":"auto","created_at":"2025-07-18 13:09:21","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":33147,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMn-SPAC XRD results before and after the hydrogen peroxide decomposition reaction.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/8493d95a1b8fca4df9ed8a78.png"},{"id":87032762,"identity":"335824e8-9a62-4a81-988b-e96f2e0dd90f","added_by":"auto","created_at":"2025-07-18 13:01:21","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":252071,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMn-SPAC XPS results before (i) and after (ii) the hydrogen peroxide decomposition reaction.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/225db2e909202bc425c47bdd.png"},{"id":87038711,"identity":"5093577a-8dc1-4d47-a97d-cb34fb953582","added_by":"auto","created_at":"2025-07-18 13:33:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2202018,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7060294/v1/d12fa9de-9082-47db-b2a8-39a76250ea5a.pdf"}],"financialInterests":"","formattedTitle":"Constant flow oxygen generation with manganese oxide supported on spherical activated carbon using hydrogen peroxide decomposition","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOxygen is the most fundamental substance required for maintaining our bodies, and it needs to be supplied continuously, anytime and anywhere. While breathing is possible through air in normal environments, survival becomes impossible in situations where oxygen is scarce, or absent, such as during diving or high-altitude mountaineering, or in cases where breathing is hindered by toxic substances, as in fires or chemical, biological, radiological, and nuclear (CBRN) incidents. To survive in these environments, technology that can supply the necessary oxygen for breathing over a certain period is essential.\u003c/p\u003e\u003cp\u003eThere are several approaches to providing oxygen for predetermined time: high-pressure compressed oxygen, electrochemical generation, and chemical production methods [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The high-pressure compressed oxygen technique stores oxygen gas in high-pressure vessels but carries explosion risks from physical impacts or heat exposure [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. While electrochemical generation offers stable oxygen supply by decomposing water, its reliance on external power sources restricts its use [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Chemical oxygen generation, which produces oxygen through compound decomposition or reactions, is a one-off. For situations requiring sustained oxygen supply, the chemical method was considered optimal, prompting further investigation.\u003c/p\u003e\u003cp\u003eThe most common chemical methods for oxygen generation involve using potassium superoxide or hydrogen peroxide. KO\u003csub\u003e2\u003c/sub\u003e is highly reactive and can produce oxygen when it comes into contact with water or carbon dioxide [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Human breath, which contains 100% relative humidity and 4.5% CO\u003csub\u003e2\u003c/sub\u003e, is enough to trigger this reaction. However, KO\u003csub\u003e2\u003c/sub\u003e must be manufactured and stored in airtight conditions, making maintenance challenging. Hydrogen peroxide, on the other hand, is a powerful oxidizer used in rocket propulsion. Yet, concentrations below 35% are non-flammable, allowing for safer oxygen production. While hydrogen peroxide naturally breaks down into water and oxygen, this process is slow. Catalysts are used to speed up the decompositions [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Common metal catalysts include Au, Fe, Cu, and Mn. Manganese (Mn) is particularly versatile due to its wide range of oxidation states (0 to +\u0026thinsp;7) found in nature, making it a stable and flexible option [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTypically, during the hydrogen peroxide decomposition reaction, as the concentration of hydrogen peroxide decreases, the rate of oxygen generation should gradually decrease. However, in the case of manganese, the generation rate can be easily controlled. Oxidized manganese produces not only oxygen but also superoxide as an intermediate product during hydrogen peroxide decomposition, resulting in a gradual increase in the rate of oxygen evolution. This means that manganese with low oxidation states exhibits active oxygen generation initially, while manganese with high oxidation states shows gradually increasing oxygen generation over time [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eWe synthesized a catalyst with manganese oxide doped on the surface of activated carbon to produce a constant amount of oxygen. This was achieved by exchanging manganese on an ion exchange resin and then appropriately adjusting the carbonization and activation time. Activated carbon itself is also a material that can decompose hydrogen peroxide, and during the activation process, the specific surface area of the activated carbon increases, as does the oxidation degree of manganese. The initial manganese product in the activation process is MnS. By optimizing the activation time and the amount of Mn precursor, we synthesized a mixture of MnO and Mn\u003csub\u003e3\u003c/sub\u003e0\u003csub\u003e4\u003c/sub\u003e, resulting in a catalyst that generates oxygen at a constant rate.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e2.1 Materials\u003c/h2\u003e\n \u003cp\u003eThe following are the reagents and substances used for the experiment. Strong acid cation exchange resin (Dow Chemical, AMBERLITE™ IRC 120 H), and manganese nitrate hydrate (Mn(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e·xH\u003csub\u003e2\u003c/sub\u003eO, 98%, Sigma-Aldrich) were used for sample preparation. Also, hydrogen peroxide solution (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e, 30%, OCI) was used for the catalyst activity test.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e2.2 Synthesis of Mn-SPAC(Spherical Activated Carbon) catalyst\u003c/h2\u003e\n \u003cp\u003eThe preparation steps of Mn-SPAC are as follows. A desired concentration of precursor solution ((0.05 N, 0.1 N, 0.2 N) was made by dissolving a quantity of Mn(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e·xH\u003csub\u003e2\u003c/sub\u003eO into 200 mL of distilled water. A strong acid cation resin (Dow Chemical) is then introduced and stirred sufficiently for ion exchange to take place. The mixture will be dried in an oven at 100°C for over 12 hours after being washed and filtered. The dried sample will then be set up in a quartz reactor, as seen in Fig. 1, and the temperature is steadily increased at a rate of 5°C/min until it reaches 900°C under a nitrogen atmosphere. Steam is then introduced into the apparatus when the temperature reaches 900°C to begin the activation process. The time of injection was adjusted o 2.5, 5, 7.5, and 10.0 hours to control the activation time.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e2.3 Characterizations\u003c/h2\u003e\n \u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003e2.3.1. Pore characteristic analysis\u003c/h2\u003e\n \u003cp\u003eN2 adsorption isotherm measurements of activated carbon were performed using a volumetric adsorption apparatus (Tristar, Micromeritics). The specific surface area was calculated using the Brunauer-Emmett-Teller (BET) equation. A measured value of P/P0 = 0.99 was used to determine the total pore volume. All sample analyses were conducted after treating the samples at 350°C under vacuum for more than 3 hours.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e2.3.2. XRD\u003c/h2\u003e\n \u003cp\u003eAn Ultima IV Diffractometer (Rigaku) was used for X-ray diffraction analysis to examine the crystallite structure of metal within the activated carbon. The scan speed was 5°/min, with a scan range of 5–80°. Cu-Kα (λ = 1.5418Å) was used as the light source.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003e2.3.3. SEM-EDS\u003c/h2\u003e\n \u003cp\u003eIn order to observe the shapes of the activated carbon samples, Scanning Electron Microscope (SEM) images were taken using Mira 3 LMU FEG (Tescan). Additionally, Energy Dispersive X-ray Spectrometer (EDS) analysis was carried out using a Quantax 200 EDS (Bruker) to identify the Mn content in the activated carbon.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec9\"\u003e\n \u003ch2\u003e2.3.4. XPS\u003c/h2\u003e\n \u003cp\u003eThe XPS experiment was performed using a monochromatic AlKα source on an ESCALAB 250 (VG Scientific, USA) at the Converging Materials Research Center, Dong-eui University (Busan, South Korea).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec10\"\u003e\n \u003ch2\u003e2.3.5 Comparison of hydrogen peroxide decomposition activity\u003c/h2\u003e\n \u003cp\u003eThe decomposition of hydrogen peroxide was conducted in a 500 mL glass reactor. To evaluate the performance differences of the samples according to various preparation conditions, 0.05 g of each sample was introduced to 200 mL of 30% hydrogen peroxide. Additionally, the samples were introduced until the amount of manganese reached a predetermined amount (7.2 mg) in order to observe the performance differences dependent on pore characteristics and manganese crystal structure when the quantity of manganese in the reaction is equal. The amount of Mn in the catalysts was also fixed to observe how the characteristics of pores and crystal structures affect the performance of the catalyst during the reaction. 200 mL of a 30% hydrogen peroxide solution was used for the reaction. A given amount of catalyst was put in the catalyst container. Then, the container was dropped into the hydrogen peroxide solution after the reactor is sealed to initiate the reaction. Using an oxygen analyzer (Rapidox 1100-EF, Cambridge Sensotec), 99.9% of the gas produced during the reaction was confirmed as oxygen. The flow rate of oxygen was measured every 30 seconds using a mass flow meter, and this measurement was also an indication of hydrogen peroxide decomposition. As all produced gas passed through a moisture trap, the flow rate was measured by using a mass flow meter. Figure\u0026nbsp;2 presents a schematic diagram of the apparatus.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Characterization of Mn-SPAC\u003c/h2\u003e\u003cp\u003eThe value of manganese content in the final samples measured by using BET, SEM-EDS analysis are found in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePhysical properties of all samples\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrecursor conc. (N)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eActivation time (h)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSample Name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMn content\u003csup\u003ea\u003c/sup\u003e (wt%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eS\u003csub\u003eBET\u003c/sub\u003e\u003csup\u003eb\u003c/sup\u003e (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eV\u003csub\u003emeso\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eV\u003csub\u003emicro\u003c/sub\u003e\u003csup\u003ed\u003c/sup\u003e (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e860\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.15 (34%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.30 (66%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1250\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.31 (43%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.42 (57%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1630\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.74 (64%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.42 (36%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2040\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.46 (83%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.29 (17%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e820\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.22 (45%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.27 (55%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1330\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.78 (69%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.35 (31%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1680\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.33 (82%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.30 (18%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1610\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.36 (88%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.19 (12%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e760\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.17 (40%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.25 (60%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e7.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.79 (72%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.31 (28%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 3\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e14.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1350\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.08 (80%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.27 (20%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMn-SPAC 3\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e18.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1140\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.00 (81%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.23 (19%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003ea: Manganese content by EDS results\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eb: BET specific surface area\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003ec: Mesopore volume\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003ed: Micropore volume\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e( ): Percentage of mesopore volume and micropore volume\u003c/p\u003e\u003cp\u003eAs seen in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the amount of Mn in the samples increased as the activation time increased from 2.5 h to 10 h when the precursor concentrations stayed constant. The Mn content for the sample with 0.05 N of precursor increased from 1.00 wt% (Mn-SPAC 1\u0026ndash;1) to 5.99 wt% (Mn-SPAC 1\u0026ndash;4), which was approximately a 5 wt% increase. As for the 0.1 N sample, the Mn amount increased from 1.00 wt% (Mn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1) to 12.21 wt% (Mn-SPAC 2\u0026ndash;4), showing approximately a 10 wt% increase. The Sample with 0.2N had an increase of 15 wt% where the Mn content rose from 3.35 wt% (Mn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;1) to 18.22 wt% (Mn-SPAC 3\u0026ndash;4).\u003c/p\u003e\u003cp\u003eFurthermore, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows sample images obtained using SEM. Samples with a precursor concentration of 0.05 N with activation time between 2.5\u0026thinsp;~\u0026thinsp;7.5 h maintained a spherical shape (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a), 3(b) and 3(c)). However, the samples with activation time greater than 10 hours were disfigured and cracked, and did not retain the spherical shape (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e(d)). This was a common phenomenon for all samples. In the case of samples with cracks, it was relatively difficult to recover the catalyst after reaction [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Thus, it was decided that samples with activation time greater than 10 hours are unsuitable for the actual process.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the values of specific surface area, mesopore volume, and micropore volume of samples using N\u003csub\u003e2\u003c/sub\u003e adsorption isotherm measurements. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e, all samples prepared with 0.05 N of precursor had increasing specific surface area as the activation time increased. However, the growth of specific surface area stopped and decreased when the activation time was greater than 10 hours for the samples prepared with precursor concentrations of 0.1 N and 0.2 N. This could be explained by the amount of manganese shown from the EDS results. The quantity of activated carbon diminished in the same amount of samples with an increase of metal. Since metal is a non-porous material, when the amount of metal exceeds a certain amount, the specific surface area decreases. The amounts of Mn in samples with precursor concentrations of 0.1 N and 0.2 N were 12.21wt% (Mn-SPAC2-4) and 18.22wt% (Mn-SPAC3-4) respectively, and 2\u0026thinsp;~\u0026thinsp;3 times greater than 0.05 N. It was found that the specific surface area of these samples decreased.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTotal pore volume is considered as the sum of mesopore volume and micropore volume. Percentages of mesopore and micropore volume to total pore volume were indicated in parentheses next to the pore volume values. There was an increase in the percentage of mesopore volume in relation to the total pore volume as the activation time increased in all the samples. Over-activation caused several nearby micropores to break down and to reform into mesopores. Therefore, the mesopore volume increased as the activation time increased [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the results of the manganese structure by the precursor concentration from the XRD analysis. It explained how the manganese structure from the activation process affects the decomposition of hydrogen peroxide. Mn-SPAC 1\u0026ndash;1 did not form any structure, whereas Mn-SPAC 1\u0026ndash;2 and 1\u0026ndash;3 had both MnS and MnO structure peaks. On the other hand, Mn-SPAC 1\u0026ndash;4 only showed a MnO structure peak (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e(a)). Mn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1 showed no peak, like that of Mn-SPAC 1\u0026ndash;1, whereas Mn-SPAC 2\u0026ndash;2 only had a MnS peak. Mn-SPAC 2\u0026ndash;3 had both MnS and MnO peaks, and Mn-SPAC 2\u0026ndash;4 had both MnO and Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e peaks (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e(b)). Mn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;1 had a MnS peak, even though it had the same sample and activation time as Mn-SPAC 1\u0026ndash;1 and Mn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1, which were amorphous. Mn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;2 had MnS, MnO, and Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e peaks, whereas Mn-SPAC 3\u0026ndash;3 and Mn-SPAC 3\u0026ndash;4 had MnO and Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e peaks (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e(c)).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eXRD analysis results showed three types of crystal structures exist in samples as follows: MnS, MnO, and Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. These results along with preparation conditions are found in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. According to the order of appearance of different peaks according to activation time, it can be seen that manganese initially formed MnS by bonding with sulfur in sulfonic acid. As the activation time increased, sulfur reacted with oxygen in the steam to become SOx and was eliminated. Manganese also oxidized and bonded with oxygen, then became MnO and Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. Meanwhile, the typical crystallite changes in manganese oxide are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In general, the changes in manganese oxide crystallite follow a path of increasing oxidation state of manganese, which was confirmed by the XRD analysis. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows that as higher the concentration of precursor increased, the oxidation rate of manganese increased, more quickly producing a MnO or Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCrystallite phases of all samples by XRD results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrecursor conc. (N)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eActivation time (h)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003eCrystallite phase\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 1\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 2\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMnS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 3\u0026ndash;3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn-SPAC 3\u0026ndash;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMnO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Comparison of hydrogen peroxide decomposition activity by samples with different activation time\u003c/h2\u003e\u003cp\u003eAll sample amounts were fixed at 0.05 g for the experiment. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e(A) shows the results from the hydrogen peroxide decomposition experiment that used samples with 0.05 N of precursor concentration. Mn-SPAC 1\u0026ndash;1 and Mn-SPAC 1\u0026ndash;3 had an increasing hydrogen peroxide decomposition activity proportional to Mn content, but it decreased with sample Mn-SPAC 1\u0026ndash;4. Despite the increase in specific surface area, it was suspected that the performance decreased due to the difference in the crystal structure of manganese. This can be deduced from Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e. As seen in Mn-SPAC 1\u0026ndash;1, hydrogen peroxide decomposition was rarely observed with samples that were void of a manganese crystal structure. Because the overall Mn amount was low, samples with a precursor concentration of 0.05 N only had below 0.2 L/min production of oxygen regardless of the activation time, which led to the early completion of the experiment.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e(B) shows the results of hydrogen peroxide decomposition for samples with a precursor concentration of 0.1 N. Both Mn-SPAC 2\u0026thinsp;\u0026minus;\u0026thinsp;1 and Mn-SPAC 1\u0026ndash;1 showed no manganese crystals and no activity in decomposing hydrogen peroxide. Mn-SPAC 2\u0026ndash;2, 2\u0026ndash;3, and 2\u0026ndash;4, which contained either MnS and MnO, MnO, or Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, exhibited improved activity, producing more than 0.2L/min of oxygen over a prolonged period. The Mn-SPAC 2\u0026ndash;3 sample exhibited a faint rise in oxygen release about 4 minutes after the initiation of the hydrogen peroxide decomposition reaction. This results from partial manganese oxidation during catalyst activation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. For Mn-SPAC 2\u0026ndash;4, higher manganese content sped up the overall reaction. Yet, the larger proportion of highly oxidized manganese caused a slower rise in oxygen production after the 4-minute mark compared to Mn-SPAC 2\u0026ndash;3. This feature was also observed with 0.2N precursor concentration samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e(C)). The oxygen flow rates for Mn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;1 and Mn-SPAC 3\u0026thinsp;\u0026minus;\u0026thinsp;2 display an immediate decreasing trend. Conversely, Mn-SPAC 3\u0026ndash;3 maintains a steady oxygen flow until a decline is observed after 20 minutes. This decrease is attributed to the fact that the reduction in oxygen production rate, resulting from the depletion of hydrogen peroxide, outweighs the oxygen flow enhancement effect induced by superoxide [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. For Mn-SPAC 3\u0026ndash;4, the exceptionally high oxidation state of Mn leads to a very slow increase in oxygen flow. This characteristic is particularly evident when measurements are performed with a constant Mn content in the catalyst (as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e(D)).\u003c/p\u003e\u003cp\u003eInter alia, Mn-SPAC 3\u0026ndash;3 produced the most linear flat pattern in terms of oxygen production and maintained a long production time. Also, the total flow of oxygen calculated using mensuration by parts satisfied the theoretical oxygen production, which was approximately 22 L (Eq.\u0026nbsp;1) that could be generated from 200 mL of 30% hydrogen peroxide solution. This showed that the sample had sufficient activity during the reaction. This means the decomposition was almost complete. Therefore, the amount of manganese contained in 0.05 g of the Mn-SPAC 3\u0026ndash;3 sample, 7.2 mg, was determined as a fixed reaction input.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Catalytic analysis after hydrogen peroxide decomposition reaction\u003c/h2\u003e\u003cp\u003eChanges in the catalyst after hydrogen peroxide reaction were confirmed through XRD and XPS analysis. After the hydrogen peroxide reaction, Mn\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Mn\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e crystal structures are observed in Mn-SPAC due to oxidation reactions (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e7\u003c/span\u003e). XPS analysis also shows that manganese oxidation occurred (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e). In the case of C1s in XPS, when comparing before (i) and after (ii) the reaction, an increase in the intensity of C-O ((i) 285.43 eV, (ii) 285.20 eV) and C\u0026thinsp;=\u0026thinsp;O ((i) 287.34 eV, (ii) 287.69 eV) can be observed due to hydration and oxidation of activated carbon. For O1s, the intensity of C-O ((i) 531.83 eV, (ii) 531. 85 eV) and C\u0026thinsp;=\u0026thinsp;O ((i) 532.92 eV, (II) 533.03 eV) increased due to hydration of activated carbon, and the intensity of Mn-O ((i) 530.69 eV, (ii) 530.85 eV) increased due to manganese oxidation. In the case of Mn2p, an increase in the intensity of Mn\u003csup\u003e3+\u003c/sup\u003e ((i) 643.20 eV, (ii) 643.30 eV) and Mn\u003csup\u003e4+\u003c/sup\u003e ((i) 644.90 eV, (ii) 644.80 eV). This is consistent with existing research reports related to manganese phase changes during hydrogen peroxide decompositon reaction. During hydrogen peroxide decomposition, manganese undergoes oxidation reactions in the presence of oxygen gas [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Another report states that when oxidized manganese is placed in an aqueous solution, the catalyst surface is hydrated to form Mn(OH)\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Mn(OH)\u003csub\u003e2\u003c/sub\u003e continuously undergoes decomposition reaction in hydrogen peroxide solution, gradually oxidizing the manganese surface [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBased on these results, we can anticipate that when the Mn-loaded catalyst is reused after recovery, due to its oxidation, the oxygen output will not be constant but will gradually increase. Therefore, this catalyst can be used as an one-off catalyst.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis research focused on developing a catalyst capable of steady oxygen evolution. The process involved ion-exchanging manganese onto a resin substrate, followed by controlled carbonization and activation procedures. This method resulted in the doping of manganese oxides onto the activated carbon surface. During activation, MnS formed initially. Through optimization of activation duration and Mn precursor concentration, a composite of MnO and Mn\u003csub\u003e3\u003c/sub\u003e0\u003csub\u003e4\u003c/sub\u003e was synthesized, yielding a catalyst exhibiting constant-rate oxygen generation.\u003c/p\u003e\u003cp\u003eWe implemented a reproducible manufacturing technology for a catalyst shape and formulation that can control the amount of oxygen generated rapidly at the initial stage of the decomposition reaction of hydrogen peroxide, which is an oxygen-generating medium, and continuously generate a constant amount of oxygen until the end of the decomposition reaction as the hydrogen peroxide is depleted.\u003c/p\u003e\u003cp\u003eThis is anticipated to enhance the technology for sustained oxygen production and delivery, enabling simpler operations to safeguard lives during emergencies and oxygen-deficient conditions resulting from diverse natural calamities and catastrophes like earthquakes and structural fires.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis work was supported by the Technology development Program (240002213) funded by the Ministry of SMEs and Startups grant (MSS, Korea). In addition, this research has been performed as a project No KK2411-30 (Development of economical low-carbon hydrogen production and storage technology from low-value carbon resources) supported by the Korea Research Institute of Chemical Technology (KRICT).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSuneel Kumar, Manoj Goswami, Smriti Mishra, Netrapal Singh, Hafsa Siddiqui, Satendra Kumar, N Sathisha,b, Mohammad Akram Khana,b, Surender kumara, \u0026amp; Avanish Kumar SrivastavaIndian, Journal of Pure \u0026amp; Applied Physics 59 (2021) 477.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFIRE AND EXPLOSION HAZARDS CAUSED BY OXYGEN CYLINDERS, Safety and Security Engineering VII (2018) 141.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYu Zhang, Ke Xie, Fangyao Zhou, Feiteng Wang, Qian Xu, Jun Hu, Honghe Ding, Peng Li, Yi Tan, Deming Li, Junfa Zhu, Huang Zhou, Changming Zhao, Sen Lin, and Yuen Wu, Adv. 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Journal of Colloid and Interface Science 243 (2001) 202.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoses Wekesa and Yonghao Ni, The Canadian Journal of Chemical Engineering 81 (2003) 968.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"korean-journal-of-chemical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"kjce","sideBox":"Learn more about [Korean Journal of Chemical Engineering](http://link.springer.com/journal/11814)","snPcode":"11814","submissionUrl":"https://www.editorialmanager.com/kjce/default2.aspx","title":"Korean Journal of Chemical Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Subscription","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Spherical activated carbon, Hydrogen peroxide, Manganese, Catalyst","lastPublishedDoi":"10.21203/rs.3.rs-7060294/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7060294/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn situations where oxygen is scarce or absent, such as during prolonged diving or high-altitude mountaineering, or in cases where breathing becomes impossible due to toxic substances like in fires or chemical, biological, or radiological incidents, a device that supplies a specific amount of oxygen is necessary for survival.\u003c/p\u003e\u003cp\u003eA Manganese Oxide/Spherical Activated Carbon (Mn-SPAC) catalyst was produced for the purpose of creating a steady oxygen supply. This was achieved through the carbonization and activation of manganese-exchanged resin under nitrogen and steam conditions.\u003c/p\u003e\u003cp\u003eThe characteristics of Mn-SPAC were analyzed using pore characteristics analysis, XRD, FE-SEM, and XPS, focusing on the amount of added manganese and carbonization time. To optimize conditions for generating a consistent amount of oxygen, the synthesized catalyst was reacted with 30% hydrogen peroxide, and the amount of oxygen produced was measured.\u003c/p\u003e\u003cp\u003eIn the optimized reaction setup, a consistent oxygen release was monitored for a duration of 20 minutes during the decomposition of hydrogen peroxide. Comparative XPS studies conducted pre- and post-reaction demonstrated the oxidation state of manganese following the process. These observations indicate that the newly developed catalyst is best suited for one-time use scenarios.\u003c/p\u003e","manuscriptTitle":"Constant flow oxygen generation with manganese oxide supported on spherical activated carbon using hydrogen peroxide decomposition","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-18 13:01:16","doi":"10.21203/rs.3.rs-7060294/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-07-14T01:22:30+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-13T12:02:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-09T13:13:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"Korean Journal of Chemical Engineering","date":"2025-07-06T21:23:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"korean-journal-of-chemical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"kjce","sideBox":"Learn more about [Korean Journal of Chemical Engineering](http://link.springer.com/journal/11814)","snPcode":"11814","submissionUrl":"https://www.editorialmanager.com/kjce/default2.aspx","title":"Korean Journal of Chemical Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Subscription","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ba6447d7-9d88-4248-ac24-4d234b8290dd","owner":[],"postedDate":"July 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-07T06:56:39+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-18 13:01:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7060294","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7060294","identity":"rs-7060294","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}