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CO 2 methanation has emerged as a promising strategy for the greenhouse gas CO 2 utilization and storage of hydrogen. However, achieving low temperature activity and high temperature stability remains challenging due to the sintering of Ni-based catalysts. To address these limitations, this study introduces a Ni–CaZrO 3 catalyst featuring a perovskite phase supported on ZrO 2 , prepared via citrate complexation and impregnation methods. In this approach, a perovskite-type oxide (PTO) of CaZrO 3 forms through a solid reaction on the surface of ZrO 2 with impregnated CaO. The formation of CaZrO 3 on Ni/ZrO 2 restrains the ZrO 2 support aggregation and reduces the particle size of Ni nanoparticles (NPs), thereby enhancing the activity for CO 2 methanation. The interaction between Ni–CaZrO 3 , and ZrO 2 effectively confines the Ni NPs and CaZrO 3 , enhancing the sintering resistance of Ni–CaZrO 3. This leads to excellent stability of the resulting catalyst for CO 2 methanation. The Ni–CaZrO 3 /ZrO 2 catalyst achieves 85% CO 2 conversion and maintains 100% methane selectivity at 300 °C, demonstrating the prolonged stability over 100 h at 550 °C. Notably, the loading of CaZrO 3 in a perovskite phase on ZrO 2 via solid surface reaction represents an interesting and valuable route, which could be extended to loading other PTOs for industrial applications. [Display omitted] • Ni and CaZrO 3 with perovskite phase loaded on ZrO 2 via solid surface reaction. • Perovskite-type CaZrO 3 reduced Ni particle size and enhanced surface area. • Improved interaction between Ni–CaZrO 3 and ZrO 2 compared to Ni and ZrO 2. • High Ni dispersion achieved 85% CO 2 conversion at 300 °C with 100% CH 4 selectivity. • Ni–CaZrO 3 confinement improved stability over 100 h at 550 °C and anti-sintering. [ABSTRACT FROM AUTHOR]

Solar light‐driven conversion of CO2 into chemicals with high calorific value is regarded as an upcoming carbon utilization technology for alleviating the energy crisis. This technique faces the challenge of low CO2 conversion and product yield due to charge recombination in the catalyst. In this paper, a dual‐reaction site heterojunction catalyst was designed and fabricated by combining NiO with Bi3O4Br nanosheets, for the separation of CO2 reduction and H2O oxidation semireactions, which effectively promoted electrons and holes separation. The resulting catalyst exhibited a high CH4 production rate (8.12 µmol/g) and selectivity (94.69%). Electron distribution and band structure were investigated to explain the satisfactory catalytic performance. In addition, combining the in‐situ DRIFTS results, a formic acid‐intermediated CO2‐to‐CH4 reaction pathway was proposed. This work aims to pave the way for CH4 production via CO2 photoreduction with high efficiency and selectivity. [ABSTRACT FROM AUTHOR]

Power‐to‐methane (PtM) offers an efficient opportunity for surplus renewable energy storage, but heat management is a major challenge for conducting the highly exothermic methanation reaction. To address this challenge, this study presents the first successful demonstration of core‐shell catalyst pellets in a pilot‐scale reactor for CO2 methanation. Experiments in a wall‐cooled fixed‐bed reactor are conducted with diluted and undiluted reactant feed under systematic variation of cooling temperature and inlet gas flow rate. The results show that core‐shell catalyst pellets significantly reduce the hot‐spot temperature while maintaining comparable reactant conversions to uncoated catalyst pellets at the same conditions. Additionally, core‐shell catalyst pellets allow for undiluted reactant feed at comparably low hot‐spot temperatures (approx. 600 °C). [ABSTRACT FROM AUTHOR]

CO2 capture and reduction with H2 (CCR) to synthesise CH4 over dual-functional materials (DFMs) possessing CO2 capture and hydrogenation abilities has recently attracted attention as a promising methodology for utilising low-concentration CO2 in air or exhaust gases without pressure and/or temperature swing operations. Much effort has been devoted to the development of Ni-based DFMs for the CCR of CH4 formation owing to their low cost and high catalytic potential for methanation. However, previous studies have been investigated under relatively high reaction temperatures (400–600 °C) and/or pressurised H2 conditions. In addition, experiments were conducted in the absence of O2 in the simulated CO2 gas. The development of efficient Ni-based DFMs under milder and more realistic reaction conditions is still necessary. In this study, we developed La-modified Al2O3-supported Ni nanoparticles (Ni–La(X)/Al2O3, X denotes the La loading) for the selective formation of CH4 from low-concentration CO2 (1%) in a simulated gas containing O2 (20%). The optimised Ni–La(15)/Al2O3 showed 99% selectivity for CH4 formation under isothermal (350 °C) and non-pressurised conditions. The effect of the La loading amount on the CCR performance was studied using X-ray diffraction, temperature-programmed surface reactions, and steady-state CO2 hydrogenation. Furthermore, the developed Ni–La(15)/Al2O3 was applied to direct capture of ultralow concentration CO2 in air (ambient direct air capture (DAC)) and methanation. [ABSTRACT FROM AUTHOR]

The cement industry is a widely used and energy-consuming sector, making it one of the largest CO 2 emitters, primarily to meet its energy demands. Therefore, this research aims to evaluate the waste heat recovery process from a cement factory to fulfill a portion of its energy requirements. In this study, four scenarios have been evaluated, including power production scenarios, hydrogen production scenarios, methanation production process evaluation scenarios, blending hydrogen with natural gas, oxy-fuel combustion scenarios, and scenarios for producing the required freshwater for the factory and the water electrolysis process. The results show that the steam Rankine cycle with the reheating process and the organic Rankine cycle with methanol working fluid with a production capacity of 24.35 MW, and a payback period of 2.4 years with levelized cost of energy being 0.005809 $/kWh, is the most favorable scenario for the power generation cycle. Also, the process of alkaline electrolysis with a hydrogen production rate of 0.1648 kg/s, and a payback period of 5.816 years, and also with the levelized cost of hydrogen being 1.001 $/kg, happened to be the most suitable hydrogen production scenario compared to other electrolysis scenarios such as PEM and SOEC. Moreover, the process of water desalination by reverse osmosis with the energy consumption of 2.7 MW of power is capable of supplying all the required water of the factory and the water electrolysis process, and it was determined as the most suitable scenario for supplying the required water. • 4E analyses of four power generation scenarios is performed for WHR in cement plants. • Comparing power generation scenarios shows RC with reheating as the most favorable. • Alkaline electrolysis emerges as the top scenario for hydrogen production. • ORC systems with reheating show energy and economic advantages despite lower power. • Reheating in steam RC yields highest power production and economic viability. [ABSTRACT FROM AUTHOR]

Efficient heterogeneous catalyst design primarily focuses on engineering the active sites or supports, often neglecting the impact of trace impurities on catalytic performance. Herein, we demonstrate that even trace amounts of sulfate (SO42−) residuals on Ru/TiO2 can totally change the CO2 reduction from methanation to reverse-water gas shift (RWGS) reaction under atmospheric pressure. We reveal that air annealing causes the trace amount of SO42− to migrate from TiO2 to Ru/TiO2 interface, leading to the significant changes in product selectivity from CH4 to CO. Detailed characterizations and DFT calculations show that the sulfate at Ru/TiO2 interface notably enhances the H transfer from Ru particles to the TiO2 support, weakening the CO intermediate activation on Ru particles and inhibiting the further hydrogenation of CO to CH4. This discovery highlights the vital role of trace impurities in CO2 hydrogenation reaction, and also provides broad implications for the design and development of more efficient and selective heterogeneous catalysts. The impact of trace impurities on catalytic performance is often overlooked. Here the authors show that trace amounts of sulfate residuals on Ru/TiO2 substantially enhance hydrogen transfer from Ru particles to the TiO2 support, shifting CO2 reduction from methanation to the reverse water-gas shift reaction. [ABSTRACT FROM AUTHOR]

In an FP-PEMFC system vent, recycling a fraction of CO 2 provides clear benefits for CO 2 utilization and rejected H 2 conversion to methane. However, the low H 2 /CO 2 ratio, deviating from the ideal stoichiometric value, presents challenges. This study examines the effects of temperature, H 2 /CO 2 ratio, residence time (F/W cat ratio), and La promoter loading on CO 2 and H 2 conversions and CH 4 selectivity over Ni–La/γ-Al 2 O 3 catalyst using a Box-Behnken design. Experimentally, higher CO 2 conversion is observed with increased temperature, H 2 /CO 2 , La loading, and reduced F/W. CH 4 selectivity, however, decreases with higher temperature and F/W but improves with higher H 2 /CO 2 and La loading. Modeling highlighted significant interactions, revealing two optimal conditions: for low La loading, high temperature, H 2 /CO 2 , and F/W are favorable; for high La loading, lower temperature and F/W, coupled with a high H 2 /CO 2 , are optimal. These findings necessitate precise control over input factors, especially H 2 /CO 2 , in optimizing methanation under low H 2 /CO 2 conditions. [Display omitted] • Effective CO 2 methanation with low H 2 /CO 2 ratios and optimal catalyst conditions. • Finding complex interaction where traditional kinetic models struggle. • Nonlinear and combined effects of temperature, La loading and/or F/W. • Combined optimization of catalyst formulation and reaction conditions. • Crucial use of RSM unraveling complex relationship for combined input optimization. [ABSTRACT FROM AUTHOR]

The synergies from integrating direct air capture and CO2 methanation are assessed and quantified. Three direct air capture and methanation processes with different integration strategies are proposed: only heat integration, direct air capture sorbent regeneration with high‐pressure H2, and complete integration in a single unit. The heat integration study via pinch analysis evaluated the potential energy demand reduction. Overall autothermal operation is achievable, as the heat generated in methanation often exceeds that required for direct air capture sorbent regeneration. A novel process combining CO2 adsorption and methanation in one reactor provided the best productivity and energy demand results. However, this design requires complex cycles and strict demands on the sorbent and catalyst, requiring further development and experimental demonstration. [ABSTRACT FROM AUTHOR]

The understanding of deactivation processes in heterogeneous catalysis is key for the development of new materials and exploration of new operation windows. In this contribution, the periodic transient kinetic method (PTK) is used to identify and separate catalyst deactivation processes for the first time. The PTK method is applied for a standard Ni/Al2O3 catalyst in CO and CO2 methanation for 24 h and compared to steady‐state experiments. For the example reactions, the study exhibits different deactivation behavior for CO and CO2 methanation. The results demonstrate that the PTK method delivers an insight into the deactivation process and furthermore gives evidence for the underlying mechanism. [ABSTRACT FROM AUTHOR]

The conversion of CO2‐H2 mixtures on Ni‐based catalysts can proceed through either the reverse water gas shift reaction (RWGS) path to produce CO or the CO2 methanation path to produce CH4. The balance between these competing reactions depends on both the reaction conditions and catalyst structure. In this study, using surface‐sensitive infrared and ambient pressure X‐ray photoelectron spectroscopies, we investigate the effect of reaction conditions on the interaction between CO2 and H2 on a Ni(111) model catalyst. Our findings highlight the occurrence of RWGS, involving direct dissociation of CO2 to CO and atomic oxygen, followed by oxygen reacting with hydrogen to form H2O, and CO and H2O desorption. Hydrogen affects the distribution of CO between hollow and top sites by displacing oxygen from the energetically preferred hollow sites. The overall balance between oxygen production from CO2 dissociation and oxygen removal by hydrogen governs the oxygen coverage and consequently the distribution of CO between top and hollow sites. This balance is significantly influenced by the reaction temperature and the H2/CO2 partial pressures. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation to methane, namely, CO2 methanation or Sabatier reaction, is a significant approach to convert CO2 and H2 to storable and transportable CH4. Low reaction temperature is the key to industrialization and has attracted plenty of research interest. Ni-based catalysts are commonly utilized owing to their favorable properties of excellent activity and economical price. However, it is still challenging to perform the Sabatier reaction under temperatures lower than 300 °C owing to the inertness of CO2. Hence, in this article, we summarize the advances of four important design principles of the Ni-based catalysts for low-temperature Sabatier reaction, namely, optimizing Ni active sites, tuning support properties, considering metal–support interactions, and choosing a suitable preparation method, which provides deep insights for the design of low-temperature CO2 methanation catalysts. Additionally, typical low-temperature CO2 methanation reaction mechanisms with *CO or *HCOO as the main intermediate and perspectives on this topic have been provided. We highlight that the rare-earth oxide-supported Ni-based catalysts with the potential reaction mechanism and corresponding reactor design would be promising for low-temperature Sabatier reaction. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiO) is one of the most popular hydrogenation catalysts. In heterogeneous catalysis, nickel oxide is used, for example, as a suitable methanation catalyst in the Fischer–Tropsch reaction not only for CO hydrogenation but also in the modified Fischer–Tropsch reaction with CO2. However, CH4 selectivity and CO2 conversion strongly depend on NiO micro- (MPs) and nanoparticles' (NPs) shape, size, and surface area. In this study, the synthesis of NiO micro- and nanoparticles was conducted using the simple solvothermal method. Different morphologies (microspheres, sheet clusters, hexagonal microparticles, and nanodiscs) were prepared using this method with different solvents and stabilizers. The prepared catalysts were tested in the hydrogenation of CO2 in a gas phase with excellent conversion values and high selectivity to produce CH4. The best results were obtained with the NiO with disc or sphere morphology, which produced methane with selectivity at a level near 100% and conversion close to 90%. [ABSTRACT FROM AUTHOR]

Herein, a Mott-Schottky heterojunction catalyst was developed by incorporating nickel (Ni) nanometallic particles supported on nitrogen-doped carbon-coated TiO 2 , enabling full-spectrum light absorption and facilitating a robust metal-support interface. This catalyst demonstrated exceptional performance in photo-thermal catalysis. Specifically, the Ni/0.5-TiO 2 @NC catalyst achieved a CO 2 hydrogenation rate of 65.3 mmol/(g cat ·h) with a CH 4 selectivity exceeding 99% under full-spectrum illumination. Remarkably, the catalyst exhibited excellent stability, maintaining its performance over two reaction cycles. The strong metal-support interface of the Mott-Schottky heterojunction catalyst enhanced photo-generated electron-hole separation efficiencies, leading to a substantial rise in catalyst surface temperature. Consequently, this phenomenon accelerated the reaction kinetics and lowered the activation energy, thereby improving overall efficiency. [Display omitted] • Mott-Schottky heterojunctions consisting of TiO 2 @NC-support and highly dispersed Ni NPs catalysts were successfully prepared. • The Mott-Schottky heterojunction catalysts exhibit rapid interface electron transfer, leading to superb carrier separation efficiencies. • The Ni/0.5-TiO 2 @NC catalyst demonstrates exceptional photo-thermal co-catalytic effects, resulting in outstanding performance in the RWGS reaction. • The in-situ DRIFTS analysis revealed that the mechanism governing the photo-thermal co-catalytic RWGS reaction follows the *HCOO pathway. Photo-thermal co-catalytic reduction of CO 2 to synthesize value-added chemicals presents a promising approach to addressing environmental issues. Nevertheless, traditional catalysts exhibit low light utilization efficiency, leading to the generation of a reduced number of electron-hole pairs and rapid recombination, thereby limiting catalytic performance enhancement. Herein, a Mott-Schottky heterojunction catalyst was developed by incorporating nitrogen-doped carbon coated TiO 2 supported nickel (Ni) nanometallic particles (Ni/x-TiO 2 @NC). The optimal Ni/0.5-TiO 2 @NC sample displayed a conversion rate of 71.6 % and a methane (CH 4) production rate of 65.3 mmol/(g cat ·h) during photo-thermal co-catalytic CO 2 methanation under full-spectrum illumination, with a CH 4 selectivity exceeding 99.6 %. The catalyst demonstrates good stability as it shows no decay after two reaction cycles. The Mott-Schottky heterojunction catalysts display excellent efficiency in separating photo-generated electron-hole pairs and elevate the catalysts' temperature, thus accelerating the reaction rate. The in-situ experiments revealed that light-induced electron transfer effectively facilitates H 2 dissociation and enhances surface defects, thereby promoting CO 2 adsorption. This study introduces a novel approach for developing photo-thermal catalysts for CO 2 reduction, aiming to enhance solar energy utilization and facilitate interface electron transfer. [ABSTRACT FROM AUTHOR]

In this study, nickel supported on various metal oxides were prepared by simple impregnation and the performance for CO2 methanation was tested. The oxide supports were all prepared by thermal decomposition of metal salts to provide comparable oxide properties such as surface area. Among the investigated oxides, nickel supported on CeO2 and Y2O3 showed the highest CO2 conversion of 90% at 320 °C with highest CH4 selectivity of 99%. The order of catalyst activity (XCO2@320°C) was reported: Ni/CeO2 ~ Ni/Y2O3 > > Ni/La2O3 > Ni/ZrO2 > Ni/Al2O3 > Ni/MgO > Ni/CaO > > Ni/MnO. The physicochemical properties of the catalysts were analyzed by TEM, BET, XRD, ICP, H2-TPR, CO2-TPD, H2 chemisorption, TGA, Raman, and XPS. From the characterization results, the catalyst activity was independent to specific surface area of catalyst and crystallite size of Ni. The amount of oxygen vacancies and weak-to-medium basic sites exhibited major roles for enhancing catalyst activity. The CeO2 and Y2O3 as reducible oxide supports not only provided abundant oxygen vacancies / basic sites, but also promoted Ni dispersion with appropriate interaction between metal and support, resulting in higher reducibility at low temperature. The reduction of catalyst at high temperature can significantly improve the performance of Ni supported on non-reducible MgO. However, the Ni/CeO2 and Ni/Y2O3 reduced at high temperature suffered from coalescence of CeO2 and Y2O3, though Ni crystallite sizes are well preserved from sintering. [ABSTRACT FROM AUTHOR]

It has been known that plastics with undegradability and long half‐times have caused serious environmental and ecological issues. Considering the devastating effects, the development of efficient plastic upcycling technologies with low energy consumption is absolutely imperative. Catalytic hydrogenolysis of single‐use polyethylene over Ru‐based catalysts to produce high‐quality liquid fuel has been one of the current top priority strategies, but it is restricted by some tough challenges, such as the tendency towards methanation resulting from terminal C−C cleavage. Herein, we introduced Ru nanoparticles supported on hollow ZSM‐5 zeolite (Ru/H‐ZSM‐5) for hydrocracking of high‐density polyethylene (HDPE) under mild reaction conditions. The implication of experimental results is that the 1Ru/H‐ZSM‐5 (~1 wt % Ru) acted as an effective and reusable bifunctional catalyst providing higher conversion rate (82.53 %) and liquid fuel (C5−C21) yield (62.87 %). Detailed characterization demonstrated that the optimal performance in hydrocracking of PE could be attributed to the moderate acidity and appropriate positively charged Ru species resulting from the metal‐zeolite interaction. This work proposes a promising catalyst for plastic upcycling and reveals its structure‐performance relationship, which has guiding significance for catalyst design to improve the yield of high‐value liquid fuels. [ABSTRACT FROM AUTHOR]

Biogas offers significant benefits as a renewable energy source, contributing to decarbonization, waste management, and economic development. This comprehensive review examines the historical, technological, economic, and global aspects of biomethane production, focusing on the key players such as China, the European Union, and North America, and associated opportunities and challenges as well as future prospects from an Australia perspective. The review begins with an introduction to biogas, detailing its composition, feedstock sources, historical development, and anaerobic digestion (AD) process. Subsequently, it delves into major biomethane production technologies, including physicochemical absorption, high‐pressure water scrubbing (HPWS), amine scrubbing (AS), pressure swing adsorption (PSA), membrane permeation/separation (MP), and other technologies including organic solvent scrubbing and cryogenic separation. The study also discusses general guidelines of techno‐economic assessments (TEAs) regarding biomethane production, outlining the methodologies, inventory analysis, environmental life cycle assessment (LCA), and estimated production costs. Challenges and opportunities of biogas utilization in Australia are explored, highlighting and referencing global projections, polarization in production approaches, circularity in waste management, and specific considerations for Australia. The review concludes discussing future perspectives for biomethane, emphasizing the importance of technological advancements, policy support, and investment in realizing its full potential for sustainable energy and waste management solutions. [ABSTRACT FROM AUTHOR]

CO2 methanation is regarded as an efficient method for upgrading CO2 to fuels and reducing environmental impacts of greenhouse gas emission. In this study, we developed Ni/ La2O2CO3 low temperature CO2 methanation catalysts by tuning the metal-support interaction via changing the morphology of catalyst supports. La2O2CO3 supports with various morphologies including nanotriangles (La2O2CO3-T), nanorods (La2O2CO3-R), and nanoparticles (La2O2CO3-P), were synthesized as the supports of Ni catalysts for CO2 methanation reaction. The CO2 methanation performance of the synthesized Ni/La2O2CO3 catalysts was found to be markedly superior to that of conventional Ni/SiO2 catalysts with the following orders: Ni/La2O2CO3-T > Ni/La2O2CO3-R > Ni/La2O2CO3-P > Ni/SiO2. In the comparative characterization of Ni/La2O2CO3 catalysts with various morphologies, TEM and H2-TPR results reveal that the Ni/La2O2CO3-T catalysts exhibit better dispersion of Ni nanoparticles and higher reducibility. Moreover, X-ray photoelectron spectroscopy (XPS), O2 and H2 temperature programmed desorption (O2-TPD, H2-TPD) results indicate that the Ni/La2O2CO3-T catalysts possess a lower oxygen vacancy formation energy leading to a higher concentration of interfacial oxygen vacancies, which enhances the adsorption hydrogen at these interfacial oxygen vacancy sites. CO2-TPD results further reveal that Ni/La2O2CO3-T catalysts own higher concentration of medium basic sites, which promote the adsorption and activation of CO2. Consequently, Ni/La2O2CO3-T catalysts demonstrate superior low-temperature CO2 methanation activity by hydrogenation of CO2 adsorbed as surface carbonates on the La2O2CO3 surfaces with hydrogen spilled over from the Ni surfaces via the interfacial oxygen vacancies to the catalyst support. [ABSTRACT FROM AUTHOR]

Photothermal CO2 methanation reaction represents a promising strategy for addressing CO2‐related environmental issues. The presence of efficient tandem catalytic sites with a localized high‐temperature is an effective pathway to enhance the performance of CO2 methanation. Here the bimetallic RuCo nanoparticles anchored on ZrO2 fiber cotton (RuCo/ZrO2) as a photothermal catalyst for CO2 methanation are prepared. A significant photothermal CO2 methanation performance with optimal CH4 selectivity (99%) and rate (169.93 mmol gcat−1 h−1) is achieved. The photothermal energy of the RuCo bimetallic nanoparticles, confined by the infrared insulation and low thermal conductivity of the ZrO2 fiber cotton (ZrO2 FC), provides a localized high‐temperature. In situ spectroscopic experiments on RuCo/ZrO2, Ru/ZrO2, and Co/ZrO2 indicate that the construction of tandem catalytic sites, where the Co site favors CO2 conversion to CO while incorporating Ru enhances CO* adsorption for subsequent hydrogenation, results in a higher selectivity toward CH4. This work opens a new insight into designing tandem catalysts with a photothermal confinement effect in CO2 methanation reaction. [ABSTRACT FROM AUTHOR]

Exsolution of metal nanoparticles (NPs) on perovskite oxides has been demonstrated as a reliable strategy for producing catalyst‐support systems. Conventional exsolution requires high temperatures for long periods of time, limiting the selection of support materials. Plasma direct exsolution is reported at room temperature and atmospheric pressure of Ni NPs from a model A‐site deficient perovskite oxide (La0.43Ca0.37Ni0.06Ti0.94O2.955). Plasma exsolution is carried out within minutes (up to 15 min) using a dielectric barrier discharge configuration both with He‐only gas as well as with He/H2 gas mixtures, yielding small NPs (<30 nm diameter). To prove the practical utility of exsolved NPs, various experiments aimed at assessing their catalytic performance for methanation from synthesis gas, CO, and CH4 oxidation are carried out. Low‐temperature and atmospheric pressure plasma exsolution are successfully demonstrated and suggest that this approach could contribute to the practical deployment of exsolution‐based stable catalyst systems. [ABSTRACT FROM AUTHOR]

Heteronuclear coordination compounds of d-metals are effective precursors for the production of bimetallic nanoalloys (Plyusnin et al., 2022) [1], which, in turn, are widely used in catalysis. Catalysts based on Rh and Cu, as well as Rh and Zn, are highly active in the process of steam reforming of hydrocarbons. Double oxalates of Rh with Cu and Rh with Zn with the general formula [(C 2 O 4)(H 2 O) 2 Rh−(μ-C 2 O 4)−M(H 2 O) 2 −(μ-C 2 O 4)–Rh(H 2 O) 2 (C 2 O 4)]·6H 2 O (M = Cu, Zn) are synthesized and structurally characterized. According to thermogravimetric analysis, the complexes completely decompose in He and H 2 atmospheres already at 300 °C with the formation of the corresponding nanoalloys in the Cu–Rh and Zn–Rh systems. Calcination in an O 2 atmosphere leads to the formation of a mixed oxide with a spinel structure. The Cu–Rh/Ce 0.75 Zr 0.25 O 2 and Zn–Rh/Ce 0.75 Zr 0.25 O 2 catalysts were prepared by impregnation by moisture capacity on a porous support followed by calcination in a hydrogen atmosphere. The obtained catalysts were tested in propane steam reforming for hydrogen production at 300–480 °C and WHSV = 10 000–40 000 cm3 h−1∙g cat −1. At these conditions the Cu–Rh/Ce 0.75 Zr 0.25 O 2 and Zn–Rh/Ce 0.75 Zr 0.25 O 2 catalysts demonstrated high selectivity for hydrogen (more than 70 %) compared to the monometallic catalyst Rh/Ce 0.75 Zr 0.25 O 2 (less than 60%). Bimetallic catalysts make it possible to increase hydrogen productivity by reducing the reaction rate of methanation of carbon oxides, which is achieved due to the presence of Cu and Zn in the catalyst structure. • New coordination compounds of rhodium with copper and zinc have been synthesized. • Bimetallic systems were obtained in a reducing and inert atmosphere. • Bimetallic Cu–Rh/CZ catalysts exhibit high hydrogen selectivity in the propane steam reforming reaction. • Bimetallic Cu–Rh/CZ and Zn–Rh/CZ catalysts reduce the rate of methanation reaction during propane steam reforming. [ABSTRACT FROM AUTHOR]

Even if huge efforts are made to push alternative mobility concepts, such as electric cars and fuel-cell-powered cars, the significance and use of liquid fuels is anticipated to stay high during the 2030s. Biomethane and synthetic natural gas (SNG) might play a major role in this context, as they are raw material for chemical industry that is easy to be stored and distribute via existing infrastructure, and are a versatile energy carrier for power generation and mobile applications. Since biomethane and synthetic natural gas are suitable for power generation and for mobile applications, they can therefore replace natural gas without any infrastructure changes, thus playing a major role.In this paper, we aim to comprehend the direct production of synthetic natural gas from CO 2 and H 2 in a Sabatier process based on a thermodynamic analysis as well as a multi-step kinetic approach. For this purpose, we thoroughly discuss CO 2 methanation to control emissions in order to maximize the methane formation along with minimizing the CO formation and to understand the complex methanation process. We consider an equilibrium and kinetic modeling study on the NiO- SiO 2 catalyst for methanation focusing on CO 2 -derived SNG. The thermodynamic analysis of CO 2 hydrogenation is preformed to define the optimal process parameters followed by the kinetic simulations for catalyst development. The investigation presented in this paper can also be used for developing machine learning algorithms for methanation processes. [ABSTRACT FROM AUTHOR]

In this work, Cox/ZnO catalysts with different CoZn mass ratios were prepared by hydrothermal and impregnation methods, demonstrating that Cox/ZnO exhibits excellent low temperature (<260°C) CO2 methanation activity and selectivity at reaction pressures as low as 0.5Mpa. In order to explain the reaction properties of Cox/ZnO at low temperature and low pressure, the physicochemical properties of the catalysts were characterized by H2-TPR, XRD, BET, XPS and CO2-TPD.The results show that, compared with pure Co3O4 and ZnO samples, when CoZn is involved in the catalyst, the interaction between CoZn improves the structural properties of the catalyst, increases the specific surface area, generates more oxygen vacancies in the Cox/ZnO catalyst, and promotes the activation of CO2.This makes the Cox/ZnO catalyst have excellent performance of CO2 methanation. At the reaction temperature of 260℃, the CO2 conversion of Co5/ZnO catalyst can reach 82.27%, and the selectivity of CH4 and CO are 99.53% and 0.047%, respectively. It remained stable for 50 hours. This work highlights the interaction between CoZn and will contribute to the development of more effective low temperature and low pressure CO2 hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

Solar-driven photo-thermal catalytic CO2 methanation reaction is a promising technology to alleviate the problems posed by greenhouse gases emissions. However, designing advanced photo-thermal catalysts remains a research challenge for CO2 methanation reaction. In this work, a series of ABO3 (A = lanthanide, B = transition metal) perovskite catalysts with Ce-substituted LaNiO3 (La1−xCexNiO3, x = 0, 0.2, 0.5, 0.8, 1) were synthesized for CO2 methanation. The La0.2Ce0.8NiO3 exhibited the highest CH4 formation rate of 258.9 mmol·g−1·hcat−1, CO2 conversion of 55.4% and 97.2% CH4 selectivity at 300 °C with the light intensity of 2.9 W·cm−2. Then the catalysts were thoroughly analyzed by physicochemical structure and optical properties characterizations. The partial substitution of the A-site provided more active sites for the adsorption and activation of CO2/H2. The sources of the active sites were considered to be the oxygen vacancies (Ov) created by lattice distortions due to different species of ions (La3+, Ce4+, Ce3+) and exsolved Ni0 by H2 reduction. The catalysts have excellent light absorption absorbance and low electron–hole (e−/h+) recombination rate, which greatly contribute to the excellent performance in photo-thermal synergistic catalysis (PTC) CO2 methanation. The results of in situ irradiated electron paramagnetic resonance spectrometer (ISI-EPR) and ISI-X-ray photoelectron spectroscopy (XPS) indicated that the aggregation of unpaired electrons near the defects and Ni metal (from La and Ce ions to Ov and Ni0) accelerated adsorption and activation of CO2/H2. At last, the catalyst properties and structure were correlated with the proposed reaction mechanism from the in situ diffuse reflection infrared Fourier transform spectrum (DRIFTS) measurements. The in situ precipitation of the B-site enhanced the dispersion of Ni, while its enriched photoelectrons upon illumination further promote hydrogen dissociation. More H* spillover accelerated the rate-determining step (RDS) of HCOO* hydrogenation. This work provides the theoretical basis for the development of catalysts and industrial application. [ABSTRACT FROM AUTHOR]

In this study, a steady-state thermodynamic equilibrium evaluation of CO2 methanation was conducted. Calculations were performed by solving the material balance equations using the equilibrium constants of CO2 methanation and reverse water–gas shift reactions. Results obtained from an analytical method developed with the aid of the Microsoft Excel platform were compared to simulations conducted using the commercially available free software COCO and DWSIM. The effects of temperature, pressure, and H2/CO2 ratio on CH4 yield, carbon oxide formation, and heat balance were investigated. The results indicate that the methanation process is highly favored by low temperatures and higher pressures with a stoichiometric H2/CO2 ratio. Under these conditions, CH4 output increases, and carbon formation is reduced, resulting in better performance. Simulations from all three models are in agreement, with minor differences noted in the DWSIM software. [ABSTRACT FROM AUTHOR]

Chemical looping combustion is a highly efficient CO2 separation technology without direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier in dual fluidized beds to generate clean CO2. The use of biomass is the focus of current research because of the possibility of negative CO2 emissions and the utilization of biogenic carbon. The most commonly proposed OC are natural ores and residues, but complete combustion has not yet been achieved. In this work, the direct utilization of CLC exhaust gas for methane synthesis as an alternative route was investigated, where the gas components CO, CH4 and H2 are not disadvantageous but benefit the reactions in a methanation step. The whole process chain, the coupling of an 80 kWth pilot plant with gas cleaning and a 10 kW fluidized bed methanation unit were for this purpose established. As OC, ilmenite enhanced with limestone was used, combusting bark pellets in autothermal operation at over 1000 °C reaching high combustion efficiencies of up to 91.7%. The fuel reactor exhaust gas was mixed with hydrogen in the methanation reactor at 360 °C and converted with a methane yield of up to 97.3%. The study showed especially high carbon utilization efficiencies of 97% compared to competitor technologies. Based on the experimental results, a scale-up concept study showed the high potential of the combination of the technologies concerning the total efficiency and the adaptability to grid injection. [ABSTRACT FROM AUTHOR]

Methanation, which synthesizes methane from CO2 and hydrogen, is one of the most promising CO2 recycling technologies. Our group are developing a noble-metal-free Ni catalyst aiming to high CO2 conversion. The reaction mechanism was estimated by clarifying the effect of the catalyst support. By improving the Ni catalyst based on the reaction mechanism, the CO2 conversion of the Ni catalyst was increased. [ABSTRACT FROM AUTHOR]

In this study, a steady-state thermodynamic equilibrium evaluation of CO2 methanation was conducted. Calculations were performed by solving the material balance equations using the equilibrium constants of CO2 methanation and reverse water–gas shift reactions. Results obtained from an analytical method developed with the aid of the Microsoft Excel platform were compared to simulations conducted using the commercially available free software COCO and DWSIM. The effects of temperature, pressure, and H2/CO2 ratio on CH4 yield, carbon oxide formation, and heat balance were investigated. The results indicate that the methanation process is highly favored by low temperatures and higher pressures with a stoichiometric H2/CO2 ratio. Under these conditions, CH4 output increases, and carbon formation is reduced, resulting in better performance. Simulations from all three models are in agreement, with minor differences noted in the DWSIM software.

Interparticle hydrogen spillover is the phenomenon of H migration over different catalyst particles, which should be a physical mixture of at least two solid catalysts. In this review, we analyze examples of enhanced catalysis based on interparticle (reverse) hydrogen spillover. Simple physical mixtures of powdered catalysts containing metal catalysts of H2 dissociation/recombination and solid catalysts with active sites for substrate activation significantly enhance catalytic reactions. These reactions include aromatic hydrogenation, CO2 methanation, and the deoxydehydration of polyols, aromatization of lower paraffins, and direct coupling of benzene and alkanes. The acceleration effect and proposed reaction pathway of each example involving interparticle (reverse) hydrogen spillover are summarized. Simple reaction systems comprising physical mixtures of at least two powdery solid catalysts should enable unique catalysis in the future with the aid of interparticle (reverse) hydrogen spillover. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni phyllosilicate was firstly synthesized by a modified microwave synthesis method. • Surfactant modification led to ultrahigh specific surface area of 535 m2 g−1 and ultrathin layer of Ni phyllosilicate of only 1.43 nm. • Hexadecyl trimethyl ammonium bromide showed higher promotion effect compared with P123 and F127. • The special structure resulted in competitive catalytic activity for CO 2 methanation. • This catalyst could exhibit high stability for 100 h in a long-term test. The traditional techniques for the synthesis of nickel phyllosilicates usually time-consuming and energy-intensive, which often lead to the formation of layers with excessive thickness due to uncontrolled crystal growth. In order to overcome these challenges, this work introduces a microwave-assisted synthesis strategy to facilitate the synthesis of Ni-phyllosilicate-based catalysts within an exceptionally short duration of only five minutes, attaining a peak temperature of merely 102 °C. To enhance the specific surface area and to increase the exposure of active sites, an investigation was conducted involving three surfactants. The employment of hexadecyl trimethyl ammonium bromide (CTAB) has yielded remarkable results, with an ultrahigh specific surface area reaching 535 m2 g−1 and an ultrathin lamellar thickness of 1.43 nm. The catalyst exhibited an impressive CO 2 conversion of 81.7 % at 400 °C, 60 L g−1 h−1, 0.1 MPa. It also demonstrated a substantial turnover frequency for CO 2 (TOF CO2) of 5.4 ± 0.1 × 10−2 s−1, alongside a relatively low activation energy (E a) of 80.74 kJ·mol−1. Moreover, the catalyst maintained its high stability over a period of 100 h and displayed high resistance to sintering. To further elucidate growth temperature gradient of the catalyst and concentration gradient of the materials involved, COMSOL Multiphysics (COMSOL) simulations were effectively utilized. In conclusion, this work breaks the limitation associated with traditional, laborious synthesis methods for Ni-phyllosilicates, which can produce materials with high surface area and thin-layer characteristics. [ABSTRACT FROM AUTHOR]

This study investigated the catalytic CO2 methanation using nickel oxide (NiO) nanoparticles and nickel oxalate (NiC2O4) as catalysts. The NiC2O4 precursor was synthesized through a chemical precipitation reaction between nickel (II) nitrate hexahydrate (Ni(NO3)2.6H2O) and oxalic acid (H2C2O4.2H2O). Nickel oxide (NiO) nanoparticles were synthesized through thermal decomposition of NiC2O4 precursor at 450 °C in air. The samples were characterized by XRD, FTIR, BET, SEM, and EDX. The XRD and FTIR analyses revealed that the NiO nanoparticles were well‐crystallized having size 17.30 nm. The BET analysis of the NiO sample revealed mesoporous NiO nanoparticles with a specific surface area (SBET) of 29.08 m2/g and a narrow distribution of pore sizes. The catalytic performance of NiO and NiC2O4 catalysts studied for the CO2 methanation in tubular packed bed reactor at 150–550 °C and 1 atm. The reduced NiO nanoparticles exhibited more catalytic activity than the decomposed NiC2O4 catalyst. At 380 °C, 1 atm, and gas hourly space velocity (GHSV) of 9000 mL g−1 h−1, the reduced NiO nanoparticle catalyst showed high catalytic activity, with a maximum CO2 conversion of 85.54 %, 99 % CH4 selectivity, and 84.69 % CH4 yield. Furthermore, the NiO nanoparticle catalyst demonstrated excellent stability after 12 h of streaming at 380 °C. [ABSTRACT FROM AUTHOR]

Strong metal‐support interactions (SMSI) featuring the formation of encapsulation overlayer around metal nanoparticles has drawn much attention in heterogeneous catalysis. Recent years, various novel SMSI phenomena have been observed and the nature of SMSI also has been revealed with the improvement of characterization techniques. Understanding the SMSI effect could deepen the insight into the structure‐activity relationship of metal‐supported catalysts, and rationally guide the design of special metal‐interface sites to manipulate catalytic behavior in chemical reaction. In this review, the research progress of SMSI and its application in heterogeneous COx hydrogenation are briefly surveyed, with emphasis on the advanced characterization, manipulation strategy and specific role of SMSI in Fischer‐Tropsch synthesis process, CO2 methanation and Reverse Water Gas Shift reaction. The current challenges and perspectives for the development of SMSI are also discussed. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of silicon-containing precursors on the facile synthesis of Ni-phyllosilicate, Stöber SiO 2 , tetraethyl orthosilicate (TEOS), sodium metasilicate (Na 2 SiO 3 ⋅9H 2 O) was used. Na 2 SiO 3 successfully reacts with the nickel nitrate to form nickel phyllosilicate at ambient temperature, owing to its strong basicity and easy hydrolysis to generate intermediates of H 4 SiO 4 and Ni(OH) 2. Stöber SiO 2 and TEOS can only convert to Ni-phyllosilicate with the assistance of NH 4 F and urea, because of the limitation of intermediates formation. The Na 2 SiO 3 -based Ni-phyllosilicate NiPs-M-12 shows the highest catalytic activity for CO 2 methanation among all the samples, whose maximum CO 2 conversion reaches 71.0% at 450 °C, 0.1 MPa, 60 L g−1·h−1 with a TOF CO2 of 2.6 ± 0.1 × 10−3 s−1 and activation energy of 83.19 kJ mol−1. The active intermediates of *HCOO and *CO are observed by in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) analysis, which can be hydrogenated to CH 3 O species with the further hydrogenation to produce the target products CH 4 and H 2 O. It also displays high long-term stability up to 100 h with high anti-sintering property. In conclusion, the recognition of the interrelationships of silicon-containing precursors and the formation of intermediates can shed light on the facile synthesis of Ni-phyllosilicate with high catalytic performance. • The room-temperature synthesis of Ni-phyllosilicate was proposed. • The properties of silicon-containing precursors were important for Ni-phyllosilicate synthesis. • The strong basicity and easy hydrolysis of Na 2 SiO 3 were the main reasons for the formation of intermediates of H 4 SiO 4 and Ni(OH) 2. • The Na 2 SiO 3 -based Ni-phyllosilicate showed high catalytic activity and stability. [ABSTRACT FROM AUTHOR]

CO 2 methanation over Ni-based catalysts provides a promising way to address the energy crisis and the environmental problems caused by massive CO 2 emissions. Nevertheless, Ni-based catalysts still face the challenges of poor activity at low temperatures. Herein, a series of MgO-promoted Ni-based catalysts supported by HNTs (halloysite nanotubes) were successfully prepared to investigate the role of MgO in CO 2 methanation. Various characterization results demonstrated that introducing MgO can enhance metal-support interaction, resulting in generating finer and more stable metal particles. Meanwhile, MgO can also offer sufficient alkaline sites and oxygen vacancies for CO 2 activation. NiMg1.0/Na-HNTs exhibited the maximum CO 2 conversion (79.0%) and CH 4 selectivity (97.5%) even at 275 °C as well as outstanding long-term stability over 100 h reaction. Additionally, in situ DRIFTS suggested that the mechanism for CO 2 methanation in this work mainly followed the formate pathway, and introducing magnesium can accelerate to convert intermediates. Briefly, this study provides an efficient low-temperature catalyst for CO 2 methanation with potential industrial applications. [Display omitted] • The metal-support interaction is strengthened through introducing MgO. • MgO-modified Ni-based catalysts possess more basic sites and oxygen vacancies. • NiMg1.0/Na-HNTs exhibits 79.0% CO 2 conversion even at 275 °C. • NiMg1.0/Na-HNTs shows outstanding long-term stability over 100 h reaction. • The formates are the main intermediates over NiMg1.0/Na-HNTs. [ABSTRACT FROM AUTHOR]

The seasonally varying potential to produce electricity from renewable sources such as wind, PV and hydropower is a challenge for the continuous supply of hydrogen for transport and mobility. Seasonal storage of energy allows to avoid the use of grid electricity when it is scarce; storage systems can thus increase the resilience of the energy system. For grid-neutral and renewable hydrogen production, an electrolyser is considered together with a Power-to-Gas seasonal storage system, which consists of a methanation, the gas grid as intermediate storage and a steam reformer. As feed stream, electricity from an own photovoltaic (PV) system is considered, and for some cases additional electricity from the grid or from a wind turbine. The dynamic operation of the plant during a year is simulated. It is possible to safely supply fuel cell vehicles with hydrogen from the grid-neutral plant without using electricity when it is scarce and expensive. To supply 135 kg H2 /day, unit sizes of 1 MW–2.9 MW for the PV system and 0.9 MW–2.6 MW for the electrolysis are required depending on the amount of available grid-electricity. The usage of grid-electricity increases the capacity factor of the electrolysis, which results in decreased unit sizes and in a better economic performance. Seasonal storage of energy is required, which results in an increased hydrogen production in summer of approximately 50% more than directly needed by the fuel cell vehicles. The overall efficiency from electricity to hydrogen is decreased due to the storage path by 10%-points to 56% based on the higher heating value. Assuming a cost-equivalent hydrogen price per driven kilometre in comparison to the actual diesel price and electricity costs of 10 Ct/kWh el from the grid, the revenues of the system are higher than the operating costs. [Display omitted] • The system combines renewable hydrogen, dynamic operation and seasonal storage. • Feasibility for continuous fuel cell vehicle supply despite resource volatility. • Winter electricity shortage compensated by hydrogen production from methane, grid-neutral. • Grid-electricity boosts electrolysis capacity, reducing unit sizes for better economics. • Profitable scenarios for grid-neutral hydrogen production shown in techno-economic analysis. [ABSTRACT FROM AUTHOR]

The effects of H2O in heterogeneous catalysis of COx (CO2, CO) hydrogenation have been intricate and controversial for many years. On the one hand, H2O molecules and their derivatives (O, H, OH) serve as reactants or co‐reactants, playing a role in modulating the reaction pathway through specific mechanisms. On the other hand, the presence of H2O can influence the catalytic performance by altering the physicochemical properties of the catalyst, such as particle size and chemical state, among others. More importantly, the dual role of H2O leads to both positive and negative outcomes, challenging our understanding of its impact. In this mini review, the relevant research results are summarized in terms of the promoting and inhibiting effects of H2O of the COx hydrogenation reaction (e. g., synthesis of methanol, Fischer‐Tropsch synthesis, methanation, etc.) and discussed from the perspective of catalyst and reaction mechanism, which may provide a certain theoretical basis for the design and development of high‐performance catalysts and referable experience for the further exploration and utilization of H2O effects on related fields as well. [ABSTRACT FROM AUTHOR]

A full-scale, 2-D, axially symmetric, heterogeneous, and transient mathematical model is utilized to evaluate the dynamic operation of a honeycomb monolithic reactor during CO 2 methanation. A base case is defined, which considers a step-type functionality for H 2 load reduction (−20%) and a Ni catalyst. The impacts of the catalyst type (Ni vs Ru), the functionality of the H 2 load disturbance, and the monolith's diameter on reactor performance are studied and compared to the base case. Results show that the use of Ru as catalyst, a ramp-type disturbance and a smaller reactor diameter generate a superior dynamic response to the H 2 feed disturbance as well as favorable effects on thermal behavior. This is despite the higher temperature gradient generated when using Ru. These findings suggest that the monolithic reactor is a viable technological option for CO 2 methanation under flow variations, such as those encountered when employing green hydrogen. [Display omitted] • Dynamic operation of a monolithic CO 2 methanation reactor is modeled. • Reactor behavior under a step-type H 2 -Load variation is evaluated. • A better dynamic performance is obtained with a Ru catalyst. • A good reactor response to step and ramp fluctuations of the H 2 load was evidenced. • A significant effect of the reactor diameter on the dynamic control was observed. [ABSTRACT FROM AUTHOR]

The research investigates converting carbon dioxide through methanation using computational fluid dynamics (CFD) in a baffled straight microchannel. The study considers different reactant distribution scenarios, including 'CO 2 Side,' 'H 2 Side,' and 'No side' streams. After finding the optimal catalyst mesh density, the model performance was validated against experimental microchannel reactor data. Results indicated that the microchannel with "CO 2 Side with Baffles" provides higher carbon dioxide conversion while maintaining the reactor temperature at a lower level. Finally, the influence of operational conditions, including feed temperature (450-400-350 °C), GHSV (120-90-60 NL/g cat/h), and H 2 /CO 2 (3.5-4.0-4.5) in the feed, was evaluated using a response surface methodology (RSM) based on the design of experiment (DOE) with carbon dioxide distribution. Multi-objective optimization results demonstrate that the optimal feed temperature, GHSV, and hydrogen-to-carbon dioxide ratio are 380 °C, 60 NL/g cat/h, and 4.43, respectively. Under these conditions, the methane yield is 60.95%, and the reactor exit temperature is around 520 °C. [Display omitted] • Reducing CO 2 emission was performed through methanation in a microchannel reactor. • CFD was used for studying the different feed distributions from side streams. • The Microchannel with Baffles and distributing CO 2 provides higher CO 2 conversion. • Adding CO 2 side streams reduces the microchannel reactor temperature. • Multi-objective optimization results in T = 380 °C, GHSV = 60 Nl/gcat/h, and H 2 /CO 2 = 4.43. [ABSTRACT FROM AUTHOR]

Currently, a power-to-gas technology that obtains electrolytic hydrogen from renewable energy sources, synthesizes it with carbon dioxide, and converts it to methane has received a great deal of attention. It is called methanation, but there are few studies examining alternative substances to replace the raw material of hydrogen. Since hydrogen does not exist naturally, it is important to find other substances that react with carbon dioxide. We focus on flammable gases formed in oil refineries and petrochemical plants. In this study, based on chemical equilibrium calculations of the so-called NASA-CEA, we tested several gases including flammable and nonflammable gases by reacting them with carbon dioxide. Some of them are included in flare stacks. The reactants in the present gas conversion were H2O, CH3OH, C2H5OH, NH3, CH3CN, CH3N2CH3, C3H8O (1-propanol), C3H8O (2-propanol), C2H6, C2H4, C3H8, C3H6, C3H4 (allene), C3H4 (propine), C6H5OH, (CH3COOH)2, HCOOH, HF, HCl, HBr, H2S, HNO3, and SiH4. The results show that substances with more hydrogen atoms per mol of reactant, such as C3H8, CH3N2CH3, and SiH4, can produce more synthetic methane. One more finding is that graphite due to coking increases proportionately to the number of carbon atoms in the chemical formula. [ABSTRACT FROM AUTHOR]

Hydrogenation of CO2 to synthesize CH4 (CO2 methanation) is one of the crucial pathways for the efficient and clean conversion of CO2. Despite extensive researches on the catalytic system for CO2 methanation, the intrinsic kinetics of CO2 methanation under specific conditions have not been thoroughly investigated. Ni/CeO2 catalyst (Ni mass fraction of 10%) was prepared using the combustion method, and samples with varying m(α-Al2O3):m(Ni/CeO2) were produced by incorporating α-Al2O3 as the internal diluent. The intrinsic kinetics of CO2 methanation of sample A with m(α-Al2O3):m(Ni/CeO2) = 25:1 were examined under the conditions of temperature of 300 °C, pressure of 1 MPa and gas hourly space velocity of 3 x 106 mL/(g⋅h). An in-depth analysis of the kinetic equations for the intrinsic CO2 methanation reaction was conducted through a combination of intrinsic kinetic tests, diffuse reflection infrared spectrum, H2-temperature programmed reaction and H2-temperature programmed desorption, etc. The results show that the CH4 generation rate under action of sample A can reach up to 41.4 mmol/(g⋅h)(H2 partial pressure is 400 kPa, and CO2 partial pressure is 120 kPa). When CO2 partial pressure is 30 kPa to 120 kPa, the CH4 generation rate exhibits linear increases with the rises of the H2 partial pressure, and is not affected by variation of the CO2 or CO partial pressure. Within this CO2 partial pressure range, the hydrogen-rich environment significantly enhances the catalytic activity of the catalyst for CO2 methanation. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation to methane (also known as "CO2 methanation") is an important way to achieve the goal of carbon neutralization. CeO2 is considered as one of the most important catalyst supports because of its abundant surface oxygen vacancies and excellent oxygen storage capacity. Transition metal Ni is also widely studied because of its excellent catalytic performance and low price. The Ni/CeO2-based catalysts formed by the combination of CeO2 and metal Ni show good application prospects in CO2 methanation. The reaction mechanisms of Ni/CeO2-based catalysts for CO2 methanation were summarized and the preparation methods of Ni/CeO2-based catalysts were introduced, and the key parameters affecting catalytic performance of CO2 methanation such as the characteristics of active centers, properties of supports, types of additives and metal-support interactions were summarized, and the catalytic performances of Ni/CeO2-based catalysts were also summarized. It is found that by modifying Ni/CeO2-based catalysts, the catalytic performances and product selectivities of Ni/CeO2-based catalysts for CO2 methanation can be regulated, which can provide new ideas for improving their catalytic performances of CO2 methanation. [ABSTRACT FROM AUTHOR]

CO2 methanation is an effective strategy for making full use of waste gases and converting them into valuable chemicals. Nowadays, the key challenge is the design of efficient catalysts to enhance low-temperature catalytic performance. The present work studies the effect of metal type on the catalytic performance of yttrium oxide-supported catalysts for CO2 methanation reaction. Ru/Y2O3, Ni/Y2O3, and Co/Y2O3 catalysts were prepared by wetness incipient impregnation method, characterized using N2-adsorption/desorption isotherm, XRD, FTIR, and H2-TPR and TGA techniques to evaluate the surface, crystal phase, and thermal stability. The catalytic test was conducted with the use of a fixed-bed reactor under atmospheric pressure. The temperature of catalytic performance was 350 °C with a supply of H2: CO2 molar ratio of 4 and a total flow rate of 200 mL/min. The main products of the reaction were CH4, and traces of carbon monoxide were present among the products. The methane yield reached 64.67%, 60.03%, and 50.82% over Ru/Y2O3, Ni/Y2O3, and Co/Y2O3 catalysts, respectively. [ABSTRACT FROM AUTHOR]

The production of methane from the methanation reaction between H2 and CO2, also known as the Sabatier reaction, is one way to diversify the global energy matrix, providing a use for CO2. This work evaluates the performance in this reaction of Ni catalysts supported on type MCM‐41 silica, synthesized y a wet impregnation method. Catalytic tests were performed for 2.5 h under atmospheric pressure. The reaction variables considered were the catalyst nickel mass content (5% and 10%), temperature (T = 400 and 550°C), reactant ratio (H2/CO2 = 4 and 2.5), and space velocity (VHSV = 5 and 10 L g−1 h−1). The catalysts were characterized by Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x‐ray spectroscopy (EDS) analyses before the reactions, and by thermogravimetric analysis (TGA), SEM, and EDS analyses after the reactions. The reaction variables were evaluated using an experimental design with 2 factors and 4 variables, in order to determine the effects of the reaction conditions on catalyst selectivity, reactant conversion, and reaction yields in terms of CH4 and CO. The best result was obtained using a reactant ratio of 2.5, space velocity of 5 L g−1 h−1, and reaction temperature of 550°C, resulting in 93.7% selectivity for methane, 69.4% CO2 conversion, 74% H2 conversion, and methane yield of 20.69%. Findings show Ni/Si‐MCM‐41 catalyst's applicability in methanation, advancing CH4 production technology, and addressing local demand while reducing CO2 emissions. [ABSTRACT FROM AUTHOR]

Integrated carbon capture and conversion (ICCC) is a promising technology to achieve cost‐effective carbon capture, usage, and storage. The development of efficient dual‐functional materials (DFMs) is crucial for advancing ICCC in industrial applications. Herein, a series of NiMg2−xCaxAl‐hydrotalcite (x = 0, 0.5, 1, 1.5, 2) DFMs are prepared and applied to integrated CO2 capture and methanation. Characterization results illustrate that magnesium stabilizes the porous structure of hydrotalcite, and calcium significantly modulates surface basicity. Codoping of Mg and Ca yields merits of both functions and leads to increased methanation efficiency. By optimizing the catalyst and operating conditions, NiMg0.5Ca1.5Al‐hydrotalcite exhibits an excellent CO2 adsorption capacity of 313 μmol g−1DFM and methane yield of 225 μmol g−1DFM with almost full selectivity toward methane at 320 °C. NiMg0.5Ca1.5Al‐hydrotalcite also exhibits good cyclability at 320 °C under ambient pressure. Overall, Mg and Ca codoped hydrotalcite offers a promising approach to construct bifunctional materials for efficient integrated CO2 capture and in situ methanation. [ABSTRACT FROM AUTHOR]

CO-selective methanation (CO-SMET) is an efficient hydrogen-rich (H2-rich) gas purification technology for proton exchange membrane fuel cells. It is vital to develop suitable catalysts with good low-temperature activity for CO-SMET reactions. In this study, RuNi/TiZrx-mixed metal oxide (RuNi/TiZrx-MMO) catalysts with different molar ratios of Zr/Ti, derived from a Zr-promoted NiTi-layered double hydroxide (NiTi-LDH) precursor were successfully prepared using the co-precipitation and wet impregnation methods. The RuNi/TiZr0.2-MMO catalyst possesses higher catalytic performance in a lower temperature window of 180–280 °C, which can reduce the CO concentration to be below 10 ppm. The characterization results obtained from XRD, BET, SEM, TEM, XPS, TPR, and TPD suggest that the addition of ZrO2 increases the surface area of the catalyst, improves the dispersion of metallic nanoparticles, increases the reducibility of Ni species on the RuNi/TiZr0.2-MMO catalyst's surface, and enhances the adsorption and activation ability of CO, resulting in remarkable catalytic performance at lower reaction temperatures. Moreover, the RuNi/TiZr0.2-MMO catalyst demonstrated long-term catalytic stability and carbon resistance. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts xRu/Ce0.75Zr0.25O2 (x = 1, 5 wt.%) are prepared by the sorption-hydrolytic precipitation. It is shown that these catalysts are active in the methanation of carbon dioxide. The composition and structural features of these compounds are studied by a complex of methods such as powder XRD, high-resolution electron microscopy, chemisorption, and X-ray photoelectron spectroscopy (XPS). It is established that catalysts obtained by the sorption-hydrolytic method contain the active component in a highly dispersed state. The catalyst with 1 wt.% Ru contains ruthenium compounds in the form of atomic clusters, while that with 5 wt.% Ru contains, along with ultrafine forms, also crystallized ruthenium-containing particles. It is shown that the initial catalysts contain oxide ruthenium compounds that are reduced to the metallic state under the methanation reaction conditions. In situ studies by powder XRD, XPS studies, temperature-programmed reduction in the hydrogen atmosphere (H2-TPR) show that metal ruthenium particles, which were obtained by the activation treatment of the catalysts as a result of heating in a hydrogen-enriched flow, promote the process of the partial reduction of the support material particles due to the spillover effect. [ABSTRACT FROM AUTHOR]

This document is a special issue of the journal Catalysts, featuring contributions from scientists in various fields discussing the topic of catalysis on zeolites and zeolite-like materials. The articles cover a wide range of topics, including the preparation and modification of zeolite-containing catalysts for the petrochemical industry, the synthesis of micro-mesoporous materials for efficient catalysis, the development of new zeolite systems for environmental catalysis, and the synthesis and characterization of nanoscale zeolites with various applications. The contributions emphasize the potential of zeolites and zeolite-like materials as catalysts due to their unique pore structures and surface properties. [Extracted from the article]

The catalytic conversion of carbon dioxide (CO2) to methane (CH4) through the "Sabatier reaction", also known as CO2 methanation, presents a promising avenue for establishing a closed carbon loop. However, the competitive reverse water gas shift (RWGS) reaction severely limits CH4 production at lower temperatures; therefore, developing highly efficient and selective catalysts for CO2 methanation is imperative. In this regard, we have developed a novel nanocatalyst comprising atomic scale Mn2O3 species decorated in the defect sites of TiO2-supported Ni-hydroxide nanoparticles with abundant oxygen vacancies (hereafter denoted as NiMn-1). The as-prepared NiMn-1 catalyst initiates the CO2 methanation at a temperature of 523 K and delivers an optimal CH4 production yield of 21,312 mmol g−1 h−1 with a CH4 selectivity as high as ~92% at 573 K, which is 45% higher as compared to its monometallic counterpart Ni-TiO2 (14,741 mmol g−1 h−1). Physical investigations combined with gas chromatography analysis corroborate that the exceptional activity and selectivity of the NiMn-1 catalyst stem from the synergistic cooperation between adjacent active sites on its surface. Specifically, the high density of oxygen vacancies in Ni-hydroxide and adjacent Mn2O3 domains facilitate CO2 activation, while the metallic Ni domains trigger H2 splitting. We envision that the obtained results pave the way for the design of highly active and selective catalysts for CO2 methanation. [ABSTRACT FROM AUTHOR]

A solution combustion synthesis (SCS) process to prepare nickel catalyst over bentonite (NiO/Ben) is reported. Compared to the traditional impregnation method, NiO/ben produced by SCS has smaller nickel particle size and higher dispersion. With a metal loading of 20 wt%, the afforded NiO/Ben demonstrates excellent catalytic activity for CO2 methanation in a dielectric barrier discharge reactor. In certain discharge conditions (H2:CO2 ratio of 5 in feed gas, discharge input power of 45 W, and gas hourly space velocity of 11 320 h−1), CO2 conversion and CH4 selectivity are as high as 55.8% and 84.6%, respectively. Under the conditions of plasma configuration, the strong interaction between the nickel species and the support plays an important role in the CO2 methanation process. [ABSTRACT FROM AUTHOR]

Methane, the simplest hydrocarbon, has a high energy density and is widely used as chemical feedstocks or fuels. Converting CO2 to methane through electrochemical reduction offers a promising strategy for managing the global carbon balance, but is a challenge due to the lack of effective electrocatalysts. Herein, the Co single atom catalyst supported by MoS2 antisite defect (Co‐MoS2) is designed from both the activity and selectivity aspects. By virtue of i) moderately electron‐deficient state (Coδ+) ensuring efficient CO2 activation and HER suppression; ii) the strong adsorption capability for intermediate enhancing selectivity; iii) the single atomic active site avoiding the formation of C2 products, Co‐MoS2 could selectively convert CO2 to CH4 with a limiting potential of −0.45 V vs. RHE, which outperforms most of the present catalysts, and is expected to be a promising substitution for Cu‐based catalysts. [ABSTRACT FROM AUTHOR]

The utilization of fossil fuel has increased atmospheric carbon dioxide (CO2) concentrations drastically over the last few decades. This leads to global warming and climate change, increasing the occurrence of more severe weather around the world. One promising solution to reduce anthropogenic CO2 emissions is methanation. Many researchers and industries are interested in CO2 methanation as a power-to-gas technology and carbon capture and storage (CCS) system. Producing an energy carrier, methane (CH4), via CO2 methanation and water electrolysis is an exceptionally effective method of capturing energy generated by renewables. To enhance methanation efficiency, numerous researches have been conducted to develop catalysts with high activity, CH4 selectivity, and stability against the reaction heat. Therefore, in this mini-review, the characteristics and recent advances of metal-based catalysts in methanation of CO2 is discussed. [ABSTRACT FROM AUTHOR]