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To develop customized sulfur–resistant catalysts for the water gas shift (WGS) reaction in the waste–to–hydrogen process, the effects of changing the nucleation conditions of the CeO2 support on catalytic performance were investigated. Supersaturation is a critical kinetic parameter for nuclei formation. The degree of supersaturation of the CeO2 precipitation solution was controlled by varying the cerium precursor concentration from 0.02 to 0.20 M. Next, 2 wt.% of Pt was impregnated on those various CeO2 supports by the incipient wetness impregnation method. The prepared samples were then evaluated in a WGS reaction using waste–derived synthesis gas containing 500 ppm H2S. The Pt catalyst supported by CeO2 prepared at the highest precursor concentration of 0.20 M exhibited the best sulfur resistance and catalytic activity regeneration. The sulfur tolerance of the catalyst demonstrated a close correlation with its oxygen storage capacity and easier reducibility. The formation of oxygen vacancies in CeO2 supports is promoted by the formation of small crystals due to a high degree of supersaturation. [ABSTRACT FROM AUTHOR]

To improve the sulfur tolerance of CeO2-supported Pt catalysts for water gas shift (WGS) using waste-derived synthesis gas, we investigated the effect of synthesis methods on the physicochemical properties of the catalysts. The Pt catalysts using CeO2 as a support were synthesized in various pathways (i.e., incipient wetness impregnation, sol-gel, hydrothermal, and co-precipitation methods). The prepared samples were then evaluated in the WGS reaction with 500 ppm H2S. Among the prepared catalysts, the Pt-based catalyst prepared by incipient wetness impregnation showed the highest catalytic activity and sulfur tolerance due to the standout factors such as a high oxygen-storage capacity and active metal dispersion. The active metal dispersion and oxygen-storage capacity of the catalyst showed a correlation with the catalytic performance and the sulfur tolerance. [ABSTRACT FROM AUTHOR]

Waste-to-hydrogen technology, a future net-zero energy mix as a clean hydrogen source, is currently a research hotspot. To upcycle waste to high-value chemicals such as hydrogen, it is necessary to study customized catalysts for water-gas shift (WGS) reactions considering waste-derived synthesis gas. Herein, we aimed to enhance the physicochemical properties of CeO 2 supported Pt catalysts by controlling the precipitation variables to develop a highly sulfur-tolerant WGS catalyst using waste-derived synthesis gas. The CeO 2 support was prepared by the classic precipitation method. During precipitation, the precipitating agent was injected at different methods and rates. In the case of the normal titration method, the KOH solution was injected into the Ce precursor dissolved solution at rates of 5, 20, and 50 mL/min. In the case of the reverse titration method, the Ce precursor dissolved solution was injected into the KOH solution at rates of 5, 20, and 50 mL/min. The as-prepared Pt/CeO 2 catalysts were applied to the WGS reaction with 500 ppm H 2 S. This work demonstrated that the titration method and titration rate affected the oxygen vacancy concentration and the active metal dispersion of the catalysts, respectively. And these properties worked in combination to determine the sulfur resistance of the catalysts. Subsequently, the high sulfur tolerance and catalytic performance of Pt/CeO 2 catalyst prepared by normal titration method with the titration rate of 50 mL/min were due to the high Pt dispersion and concentration of oxygen vacancies. [Display omitted] ● Pt/CeO 2 catalysts with different precipitation variables for WGS were studied. ● Titration methods (normal, reverse) are related to oxygen vacancy concentration. ● Titration rates (5, 20, 50 mL/min) affect the Pt0 dispersion of the catalysts. ● Pt/CeO 2 (N50) exhibited the best catalytic performance and sulfur resistance. ● Oxygen vacancies and Pt dispersion have a complex effect on the sulfur resistance. [ABSTRACT FROM AUTHOR]

Water-gas shift reaction was applied to upcycle a waste-derived synthesis gas, which contains sulfur as an impurity. Pt/CeO 2 was chosen as an appropriate catalyst through a metal and support screening study. The Pt/CeO 2 catalyst showed stable catalytic activity without any deactivation for 100 h when the H 2 S was injected to 100 ppm, and still showed a sulfur tolerance even after 1,000 ppm of H 2 S was injected. In particular, the catalytic activity was fully regenerated when the H 2 S injection was stopped, regardless of the H 2 S concentration. The high sulfur tolerance and regeneration rate of Pt/CeO 2 catalyst was due to the high oxygen storage capacity. This accelerates the redox mechanism of the water-gas shift reaction, and also helps the removal of the adsorbed sulfur on the Pt through the oxidation reaction with the mobile oxygen originated from the CeO 2. • Waste-derived syngas includes sulfur, which act as a poison to catalyst. • Active metal and support screening study was conducted. • Pt/CeO2 catalyst showed high sulfur tolerance and regeneration rate. • High oxygen storage capacity of the Pt/CeO2 was the key of superior performance. • Mobile oxygen attacked the adsorbed sulfur, resulting to the catalyst regeneration. [ABSTRACT FROM AUTHOR]

Various noble metals (Pt, Rh, Ru, and Pd) were supported on CeO 2 to understand their sulfur-tolerant catalytic activity. The synthesized catalysts were applied to the water-gas shift reaction in the waste-to-hydrogen process with the injection of 500 ppm H 2 S. Among the samples, the PtCe catalyst showed the highest sulfur tolerance and recovery of catalytic activity. Considering the catalytic reaction results and physicochemical properties, the sulfur tolerance of the catalyst is affected by oxygen vacancies and redox properties, which are closely related to the interaction between the metal and the CeO 2 support. In addition, the oxygen storage capacity concentration was used as an indicator for classifying the recovered catalyst and the non-recovered catalyst which had been poisoned by sulfur. [Display omitted] • CeO 2 -based noble metal catalysts are tested for sulfur-injected water gas shift. • Pt-loaded catalyst showed strong sulfur tolerance and regeneration. • Sulfur tolerance is strongly related to oxygen storage capacity of the catalyst. • Regeneration trends are clearly classified based on the oxygen storage capacity. • Certain oxygen vacancy is required for the regeneration of sulfur-poisoned catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review introduces the WGS reaction and catalyst of diverse types of syngas. • Natural gas-, biomass-, waste-, and coal-derived syngas are categorized. • Customized reaction conditions/catalysts are compared based on syngas type. • Some similarities were identified through the comparison of syngas characteristics. • CO concentration and the presence of H 2 S are the main consideration factors. The conventional hydrogen production process from natural gas includes a water–gas shift reaction (WGSR) as a core step to remove carbon monoxide and produce additional hydrogen. The WGSR can be further applied to the upcycling of other types of synthesis gases, such as biomass, municipal solid waste, and coal-derived synthesis gas. We have focused on the reaction conditions and catalysts for the WGSR dealing with diverse types of feed gases for the last 10 years to understand the development progress. Based on the categorization (by the type of feed gas), the tested catalysts, capacity, temperature, feed gas composition, steam-to-carbon ratio, and the performance of the catalyst are carefully compared. This review provides insight into the current research trends and perspectives for target-oriented WGSR in each type of feed gas, which can give clues for customization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zr-doped Co/CeO 2 cubic catalysts were developed for waste-to-hydrogen via WGS. • Zr doping concentrations in cubic CeO 2 were varied to assess Zr effects on OSC. • Higher Zr content significantly improves OSC and stability. • Low Zr has high initial activity due to high BET area, dispersion and sufficient OSC. • OSC is identified as key to efficient WGS reaction performance. Zr was doped on Co/CeO 2 cubic catalysts to enhance oxygen storage capacity (OSC) in the water–gas shift (WGS) reaction using waste-derived synthesis gas. Zr concentrations (0, 0.22, 1.86, and 7.01 wt%) were changed systemically to see the effect of Zr on OSC. The analysis of the characteristics reveals that the newly synthesized catalysts demonstrate superior OSC compared to the CeO 2 supported Co catalyst previously developed by our lab. The catalyst with the highest Zr content (7.01 wt%) demonstrated substantial carbon monoxide conversion after 50 h, highlighting the critical role of OSC in catalytic WGS stability. Conversely, a minimal Zr addition (0.22 wt%) resulted in the highest initial catalytic activity, which was attributed to an above-average Brunauer–Emmett–Teller surface area, Co dispersion, and relatively sufficient OSC. The findings emphasize that Zr doping considerably enhances the OSC of Co/CeO 2 cubic catalysts, which is essentially linked to catalytic performance such as stability and activity. These insights confirm that precise Zr doping is a crucial strategy for modulating OSC, thereby enhancing the physicochemical properties of catalysts for improved efficiency in environmental and industrial applications, particularly in WGS reactions. [ABSTRACT FROM AUTHOR]

Waste-to-hydrogen processes are a way to produce hydrogen from waste and reduce the amount of landfill/incineration of wastes simultaneously through the gasification of waste. The water-gas shift (WGS) reaction is a key step in this waste-to-hydrogen process by removing the CO and producing additional H 2. A nanofiber-structured CoFe 2 O 4 catalyst was synthesized by the electrospinning method, and the catalytic performance in WGS using waste-derived synthesis gas was compared with that of catalysts prepared by sol-gel, hydrothermal, and co-precipitation methods. The CoFe 2 O 4 catalyst synthesized by the electrospinning method showed a clear nanofiber structure and revealed a superior redox property. This superior redox property, which has a large relation with the high oxygen storage capacity of the catalyst, induced the formation of an active phase (Co0 and Fe 3 O 4) in CoFe 2 O 4. As a result, the nanofiber structured oxygen defective CoFe 2 O 4- x prepared by the electrospinning method showed the best catalytic activity in this study. [Display omitted] • The CoFe 2 O 4 spinel catalyst were prepared by various methods. • The samples were tested in water-gas shift reaction for waste-to-hydrogen. • The samples synthesized by electrospinning method showed clear nanofiber structure. • Nanofiber-structured sample showed superior redox property. • Nanofiber-structured sample showed highest catalytic activity among the samples. [ABSTRACT FROM AUTHOR]

Achieving Net Zero 2050 through decarbonization and securing next-generation clean energy have become the most important challenges. One of the pathways that make these possible is the paradigm shift to the hydrogen economy society. "Blue hydrogen" production controls CO 2 emissions by applying carbon capture, utilization and storage (CCUS) technology to the existing gray hydrogen process. Performance improvement by identifying key performance-influencing factors of materials for each unit can be a valid approach to effectively solve the aforementioned issues. This review highlights the recent relevant research on materials applied to each unit process of blue hydrogen production (catalysts for reforming, water-gas shift, preferential oxidation, sorbents and oxygen carriers for desulfurization, pressure swing adsorption, CCUS) and deals with key performance-influencing factors and acceptable performance criteria for integration with CCUS. For desulfurization, PSA, and CCUS sorbents, maintaining pore structure is crucial. Performance can be improved by combining liquid and solid adsorbents, as well as using specific molecular sieves and porous supports. In reforming, water-gas shift, and preferential oxidation, achieving high metal dispersion is crucial. Enhancing metal-support interaction through proper support application prevents sintering and boosts catalytic performance. [Display omitted] • Achieving "Net Zero 2050″ through decarbonization is humanity's paramount task. • Blue hydrogen offers a path to decarbonization and clean energy transition. • This review provides research progress on catalysts and sorbents for blue hydrogen. • Acceptable performance criteria of materials for blue hydrogen are proposed. • Specially, the focus is on finding improvement points via identifying key factors. [ABSTRACT FROM AUTHOR]

We designed the customized Ni-MgO-Al 2 O 3 catalyst for the dry reforming of methane (DRM) using coke oven gas (COG). The calcination conditions of the catalysts were systematically controlled to investigate the effect of the surface properties of the catalysts on catalytic performance. The characterization results showed that the physicochemical properties of the catalyst, such as basicity, BET surface area, Ni dispersion, Ni crystallite size, and reducibility varied with the calcination temperature. Considering the gas composition of the COG, the operating conditions were also optimized by calculating thermodynamic equilibrium to maximize the CO yield and minimize carbon deposition. As a result of catalytic evaluations conducted at selected operation conditions, we found that the catalytic activity is strongly affected by the number of Ni active sites correlated with the Ni dispersion and reduction degree. In addition, the basicity of the catalyst played an important role in CO 2 adsorption and activation, which is related to coke resistance. Among the prepared catalysts, the Ni-MgO-Al 2 O 3 (calcination temperature = 800 °C) catalyst exhibiting best catalytic performance due to a large number of Ni active sites and relatively good basicity, was selected as the optimal catalyst, and the possibility of commercialization was confirmed through the long-term stability test and start-up/shut-down test. [Display omitted] • A Ni–MgO–Al 2 O 3 catalyst was customized for dry reforming of coke oven gas. • The surface properties were controlled by calcination conditions. • The operating conditions were optimized by calculating thermodynamic equilibrium. • The number of Ni active sites and basicity were key for catalytic performance. • The optimized catalyst showed the possibility of stable synthesis gas production by utilizing byproduct coke oven gas and CO 2 emitted from steelmaking process. [ABSTRACT FROM AUTHOR]

Research is being actively conducted to improve the carbon deposition and sintering resistance of Ni-based catalysts. Among them, the Al2O3-supported Ni catalyst has been broadly studied for the dry reforming reaction due to its high CH4 activity at the beginning of the reaction. However, there is a problem of deactivation due to carbon deposition of Ni/Al2O3 catalyst and sintering of Ni, which is a catalytically active material. Supplementing MgO in Ni/Al2O3 catalyst can result in an improved MgAl2O4 spinel structure and basicity, which can be helpful for the activation of methane and carbon dioxide molecules. In order to confirm the optimal supports' ratio in Ni/MgO-Al2O3 catalysts, the catalysts were prepared by supporting Ni after controlling the MgO:Al2O3 ratio stepwise, and the prepared catalysts were used for CO2 reforming of CH4 (CDR) using coke oven gas (COG). The catalytic reaction was conducted at 800 °C and at a high gas hourly space velocity (GHSV = 1,500,000 h−1) to screen the catalytic performance. The Ni/MgO-Al2O3 (MgO:Al2O3 = 3:7) catalyst showed the best catalytic performance between prepared catalysts. From this study, the ratio of MgO:Al2O3 was confirmed to affect not only the basicity of the catalyst but also the dispersion of the catalyst and the reducing property of the catalyst surface. [ABSTRACT FROM AUTHOR]