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CO selective methanation (CO-SMET) is an important method for removing CO from reforming gases. Ru/Al 2 O 3 catalyst prepared by the conventional impregnation method is the most commonly used CO-SMET catalyst and exhibits a spontaneous eggshell-type distribution due to the strong interaction between Ru and Al 2 O 3. The eggshell-type Ru/Al 2 O 3 catalysts exhibited reduced catalytic activity at a high Ru loading due to the agglomeration of Ru at the thin eggshell layer, making it difficult to meet practical CO removal requirements. To address this, four types of acids were individually introduced into the impregnation solutions to weaken the strong interaction between Ru and Al 2 O 3. The prepared catalyst introduced with HNO 3 exhibited a near-uniform distribution and relatively high catalytic activity, but low CO selectivity. Subsequently, a two-step impregnation method was proposed to form a unique distribution. The prepared Ru/Al 2 O 3 catalyst with a Ru loading of 1.5% demonstrated an excellent CO-SMET performance by removing CO to below 10 ppm with a wide temperature range of 213 °C–257 °C, corresponding to CO selectivity ranging from 87.5% to 64.4%. • Conventional Ru/Al 2 O 3 catalysts exhibit spontaneous eggshell-type distribution. • Eggshell-type catalysts exhibit reduced CO-SMET performance at high Ru loading. • Introducing acid in impregnation solution can disrupt eggshell-type distribution. • Two-step impregnated Ru/Al 2 O 3 catalyst exhibits excellent CO-SMET performance. [ABSTRACT FROM AUTHOR]

The CO2 methanation reaction, or Sabatier reaction, is experiencing renewed interest in the context of large‐scale recycling of point CO2 emissions, leading to the power‐to‐gas technology. The reaction represents a flexible route to transform CO2 into methane by hydrogenation with (green) dihydrogen. This exothermic transformation takes place at a reasonable rate at temperatures above 200 °C and is directed to the targeted product at low temperatures. The CO2 methanation nevertheless remains kinetically limited due to the chemical stability of CO2 and the high bond dissociation energy for C═O in CO2. Therefore, the current urgent demand is for the development of catalysts and associated processes with superior activity for CO2 activation at low temperatures. This critical review aims to overview the state of the art of this low‐temperature technology using thermal, plasma and photo‐assisted catalysis. We summarize research advances around low‐temperature CO2 methanation, focusing on catalyst formulations (metal, supports and promoters), reaction mechanisms and suitable activation processes. We discuss each of these critical aspects of the technology and identify the main challenges and opportunities for low temperature (≤200 °C) CO2 methanation. [ABSTRACT FROM AUTHOR]

CO 2 methanation is considered as a promising reaction in the context of mitigating climate change by reducing CO 2 emissions and providing a renewable source of methane fuel. The CeNiO 3 and LaNiO 3 perovskite catalysts were synthesized using the sol-gel method. The effect of perovskite structure on the catalytic activity was studied. The results were compared with Ce-supported and La-supported Ni catalysts (Ni/CeO 2 & Ni/La 2 O 3). Different methods including XRD, N 2 adsorption-desorption, H 2 -TPR, FE-SEM, and CO 2 -TPD, were employed for the characterization of the catalysts. The perovskite catalysts are more active than the corresponding supported catalysts. Among all prepared catalysts CeNiO 3 perovskite catalyst showed highest activity 80% conversion and 98% selectivity at 300 °C. Weak basicity, high active metal reducibility and the synergy between Ni and Ce due to perovskite structure are the responsible factors for high activity of CeNiO 3 catalyst. The CeNiO 3 catalyst showed excellent stability for CO 2 methanation during 24 h of time on study with different GHSVs. The effect of calcination temperature was also studied on CeNiO 3 catalyst at 650, 750 and 850 °C temperatures. Raman spectra concluded that the oxygen vacancy sites increased with rise of calcination temperature from 650 to 750 °C and decreased with further increase in temperature. The CeNiO 3 calcined at 750 °C (CeNiO 3 -750) showed highest activity among all other catalysts. The increased activity is due to increased oxygen vacancies which ensures that Ni nanoparticles are highly dispersed. [Display omitted] • CeNiO 3 & LaNiO 3 perovskites were prepared successfully by sol-gel method. • Ni/CeO 2 & Ni/La 2 O 3 catalysts prepared by wet impregnation method for comparison studies. • CeNiO 3 perovskite showed the highest activity for CO 2 methanation at 300 °C. • The effect of calcination temperature of CeNiO 3 on CO 2 methanation was examined. • Rising calcination temperature from 750 to 850 °C lowered CeNiO 3 oxygen vacancies. [ABSTRACT FROM AUTHOR]

This manuscript discusses the advancements and historical development of solid oxide electrolysis (SOE), co-electrolysis, and methanation technologies, addressing the performance fundamentals and system integration challenges in the context of the EU's 2050 climate neutrality goals. SOE technologies, characterized by their high efficiencies and ability to operate at elevated temperatures, offer significant advantages in hydrogen production and power generation. Co-electrolysis of steam and carbon dioxide in SOEs provides a promising pathway for syngas production, leveraging carbon capture and utilization strategies to mitigate carbon emissions. Additionally, catalytic methanation processes described within facilitate the synthesis of methane from carbon oxides and hydrogen, which could be integral to renewable energy storage and grid-balancing solutions. Historical analysis provides insights into the evolution of these technologies from early experiments to modern applications, including their role in space programmes and potential for industrial scale-up. The current state of research and commercialization, highlighted through various system designs and operational enhancements, suggests that SOEs are crucial for sustainable energy transformations, underscoring the necessity for continued innovation and deployment in relevant sectors. [ABSTRACT FROM AUTHOR]

High‐entropy oxides (HEOs) are an emerging class of materials whose compositional complexity has garnered attention because of their tailorable chemistries and unique properties arising from extreme configurational entropy. Solid‐state methods are often employed to synthesize HEOs, but such methods result in poor material properties for catalytic processes, leaving HEOs less studied for catalysis. Here we utilize different wet‐synthesis strategies to produce porous HEOs and investigate their performance in heterogeneous CO2 hydrogenation to methane. Specifically, HEOs were synthesized using hydrothermal, co‐precipitation, and solvothermal methods, resulting in different morphologies like platelets or spheres. Of the tested materials, HEOs with 2‐D platelets derived from hydrothermally‐synthesized high‐entropy layered double hydroxides had superior catalytic performance, especially in low‐temperature regimes (<300 °C). K‐edge XANES indicated that metallic sites (Ni0‐Co0) were formed during the reaction, and these metallic sites are dispersed into the HEO matrix which is confirmed by STEM/elemental mapping. This facile synthesis approach allows for realized synergy between the metallic sites and the HEO support, leading to superior performance for CO2 methanation compared to low‐entropy counterparts. Finally, this study illustrates how HEOs offer new avenues of tailorability in terms of the interplay between support, active site and reaction temperatures for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Poly(heptazine imide) (PHI), one of the crystalline or long‐range ordered allotropes of polymeric carbon nitride, is a promising polymeric photocatalyst; however, preparation of highly crystalline PHI remains a challenge. Herein, through a bottom‐up strategy involving repair of structural defects and increase of specific surface area of melon precursor, we prepared PHI nanorods with dramatically improved long‐range order. The resulting PHI exhibited a shift of product selectivity in CO2 photoreduction from CO to CH4 with a high methanation activity in contrast to the pristine PHI with relatively low long‐range order. The improvement of long‐range order for PHI remarkably enhanced the separation efficiency and transfer kinetics of photogenerated charges as well as the adsorption for *CO intermediate. This study revealed the relationship between the precursor structure and PHI crystal growth in ionothermal synthesis, and also showcased the great potential of highly crystalline PHI in artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Hydrocarbon fuels have caused significant environmental damage, leading to a search for renewable alternatives like hydrogen. The water-gas shift reaction (WGSR) is a key process in hydrogen production, especially in ammonia synthesis. Typically, WGSR occurs in two stages: low-temperature (LT-WGSR) at 180–250 °C and high-temperature (HT-WGSR) at 310–450 °C. Traditional HT-WGSR catalysts use Fe–Cr, but the presence of carcinogenic hexavalent chromium (Cr6+) poses environmental risks, necessitating safer alternatives. This study explores the replacement of chromium with aluminum (Al) and cerium (Ce) in Fe-based catalysts, synthesized via mechanochemical methods. Characterization revealed that Fe–Ce catalysts (85:15 ratio) exhibited superior thermal stability. Additionally, varying nickel (Ni) contents were tested to improve activity, with 10% Ni offering the best performance despite some methane by-products. The study also examined the impact of reduction and calcination temperatures, GHSV, and steam/gas ratios on the catalyst's efficiency. [Display omitted] • The mechanochemical method was used for the preparation of CeO 2 –Fe 2 O 3 support. • The catalytic efficiency of the samples was examined on the high-temperature water gas shift reaction. • The catalyst prepared with CeO 2 showed the best performance compared to those prepared with Al 2 O 3 and Cr 2 O 3. • The Ni (10%) -FeCe catalyst demonstrated the highest efficiency in this process with minimal methane suppression. • The impact of various nickel content and processing conditions was also studied. [ABSTRACT FROM AUTHOR]

An exhaustive review of the available literature regarding the kinetic models for the methanation of COx gases to produce natural gas (CH 4) is reported. Since the oldest and recent reported kinetic studies about this topic were discussed and analyzed. The characteristics of the experimental studies such as the reaction system, operating conditions, catalyst used, and the experimental procedure, as well as the derived reaction rate equations, reaction rate coefficients and activation energies are highlighted. The results of the various kinetic models are also discussed in order to identify appropriate approaches that can be used as reference to develop new kinetic models. Most of the works reported values of reaction order of 0.2–1 and activation energies of 75–110 kJ/mol in a temperature range of 220–450 °C. Average absolute error (ε) values were calculated to evaluate the accuracy of the predicted data, which resulted to be in the range of 0.15 %–8.08 % showing generally a good agreement. • Main reactions that should be considered for kinetic modeling are: methanation of CO 2 and CO, and RWGS. • Using appropriate kinetic model helps define proper operating conditions to produce methane at commercial scale. • LHHW kinetic model is more adequate to represent the COx methanation. [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]

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 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 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]

CO2 reduction by sunlight under mild reaction conditions is a research area of increasing interest expected to favor decarbonization and produce fuels and chemicals in the circular economy. We hereby report on the development of a series of titanium oxide‐based solids produced by calcination of MIL‐125(Ti)‐NH2 decorated with RuOx nanoparticles (1 wt %) material at temperatures from 350 to 650 °C and used as photocatalysts for CO2 methanation under simulated sunlight irradiation (45 mW/cm2) at <200 °C and 1.5 atm total pressure. The material synthesized at 350 °C produced the highest photoactivity of the series (4.73 mmol g−1 CH4 at 22 h and an apparent quantum yield at 400, 500 and 750 nm of 0.76, 0.65 and 0.54 %, respectively), comparing favorably with the activities of other MOF‐based materials reported so far. Insights into the material's photocatalytic performance and a study of the possible reaction pathways during CO2 methanation were obtained by electrochemical impedance, electron spin resonance, photoluminescence and in situ FT‐IR spectroscopies together with transient photocurrent and hydrogen temperature programed desorption measurements. The study showed the possibility of using MOF‐based materials as precursors to develop metal oxide photocatalysts with enhanced activities for solar‐driven gaseous CO2 photomethanation. [ABSTRACT FROM AUTHOR]

Thermocatalytic conversions of carbon dioxide (CO2) to value‐added products offer promising approaches to achieving net negative emissions. The catalysts for CO2 conversions, particularly for CO2 hydrogenation reactions, usually involve more than one catalytic sites working together. In this review, we first introduce the advanced characterization techniques used to identify the catalytic sites in CO2 hydrogenation catalysts, sites for hydrogen (H2) activation and CO2 adsorption/activation. We then discuss how the dual or multiple‐site configurations influence the catalytic activity and selectivity in reactions such as reverse water‐gas shift (RWGS), CO2 methanation, and CO2 hydrogenation for methanol (MeOH). We finally explain the Catalytic Sites Contiguity (CSC) concept that our research group developed from the work in CO2 reforming of methane and use it to understand the relationship between the spatial arrangement of catalytic sites and the efficiency of reactant activation and conversion in recent publications on MeOH synthesis from CO2 hydrogenation. We hope our insights into the impact of CSC on catalytic performance lead to a potential top‐down design method in optimizing the CO2 hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

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]

The global push for sustainable energy solutions has highlighted the importance of producing carbon-zero hydrogen (H 2) directly from petroleum reservoirs. In-situ combustion gasification (ISCG) presents a groundbreaking method to harness the potential of heavy oil reserves for clean hydrogen production. Although simulations have demonstrated the considerable promise of ISCG, the key reactions controlling hydrogen generation require experimental validation, and the underlying mechanisms remain largely unexplored. This research aims to describe the chemical reactions and mechanisms responsible for hydrogen generation during the ISCG of heavy oil. Using a specially designed kinetic cell, we conducted combustion and gasification experiments with heavy oil and coke. The findings revealed that clay minerals in the reservoir sand act as catalysts in the oxidation reactions of heavy oil by shifting reactions to lower temperatures by approximately 20 °C. Hydrogen production began at 450 °C and peaked at 900 °C, with coke gasification and the water-gas shift reaction being the primary mechanisms. Additionally, methane was produced due to hydrogen consumption via methanation reactions, and minerals in the reservoir sands were found to inhibit hydrogen production by increasing hydrogen consumption and methane generation at temperatures above 800 °C. Controlling the reservoir temperature within an optimal range between 450 and 800 °C can enhance hydrogen generation by managing the process mechanisms. This study provides a detailed examination of the ISCG process for heavy oil, paving the way for future development of kinetic models to simulate hydrogen production through ISCG. It also emphasizes the significance of mechanistic control in enhancing hydrogen generation and suppressing hydrogen consumption reactions. • The chemical reactions and mechanisms of H 2 generation via ISCG were described. • H 2 generation is dominated by coke gasification followed by the water gas shift. • H 2 consumption by methanation reactions increases at high temperatures. • Minerals in reservoir sands effect combustion and gasification reactions during ISCG. • H 2 production can be optimized by mechanistic control of the ISCG process. [ABSTRACT FROM AUTHOR]

Nickel-based catalysts are widely studied for water-gas shift (WGS), a key intermediate step in hydrogen production from carbon-based feedstocks. Their viability under practical conditions is limited at high temperatures when Ni aggregates and converts CO to methane, an undesirable side product. Because experimental and computational studies identify undercoordinated Ni step sites as most active toward CH4 formation, we eliminate Ni step sites by atomically dispersing Ni into networked, nanoparticulate CeO2 aerogels. The mesoporous catalyst with 2.5 atomic % Ni in CeO2 is highly active for WGS, converting near-equilibrium levels of CO at 350°C, while no CH4 is detected at the limit of detection (<2 parts per million). In contrast, supporting low weight percentages of Ni clusters or nanoparticles on CeO2 aerogels leads to methanation. The CH4 yield produced by the atomically dispersed Ni-substituted CeO2 aerogel is over an order of magnitude lower than previously reported Ni-based catalysts claiming methane suppression, marking an important advance in the development of WGS catalysts. [ABSTRACT FROM AUTHOR]

Utilizing near zero‐carbon NH3 as fuel in engines is promising for carbon‐neutrality. However, the application of NH3 into the engine suffers from the intrinsic poor combustion characteristics of NH3 and the emission of harmful NOx exhausts. Herein, we proposed and successfully confirmed a novel scenario for converting a conventional “CH4‐fueled” engine to “NH3‐fueled” engine. Specifically, CH4 was used to power the internal combustion engine and release CO2 as the exhaust. Afterwards, we put forward two routes to convert the exhaust and NH3 into N2 and CH4 for enclosing the carbon cycle. The first “spatially decoupled” route splits the exhaust treatment into NH3 cracking over Ru clusters on the calcined Mg−Al hydrotalcite (Ru/MAO) and CO2 methanation over a commercial Ni/Al2O3. Both NH3 and CO2 were almost completely converted into the target products under their respective optimal conditions. The second “spatially coupled” route refers to an one‐pot reaction of NH3 and CO2 into N2, CH4, and H2O. Due to the mismatch of reaction conditions and the competitive adsorption of reactants, the conversions of NH3 and CO2 were lowered to 80.1 % and 49.3 %, respectively, over Ru/MAO under 1 bar (CO2:NH3=3 : 8) at 550 °C. [ABSTRACT FROM AUTHOR]

Developing solid‐solution nano‐alloys from immiscible metals has garnered significant interest; however, the high formation entropy poses substantial challenges in synthesis, hindering a comprehensive understanding of the catalytic mechanisms under alloying effects. Herein, the synthesis of small‐sized (≈2.5 nm) RuxNi1‐x solid‐solution alloy nanoparticles with precisely controlled Ru/Ni ratios across a broad compositional range is reported for the first time, despite their bulk immiscibility. The Ru0.76Ni0.24/TiO2 catalyst, with an optimized Ru/Ni ratio, delivers superior photo‐thermal catalytic activity for CO2 methanation, achieving a CH4 production rate of 3.58 mol gmetal−1 h−1 with 94% selectivity at 250 °C under light irradiation, representing a 2.82‐fold enhancement over monometallic Ru/TiO2. Comprehensive investigations reveal that the reconstruction of electronic structure at Ru–Ni active sites enhances the adsorption/activation of reactants, promotes the transformation of intermediate HCO3* to HCOO*, and facilitates the separation of the photo‐generated charge carriers witnessed by the femtosecond time‐resolved transient absorption (fs‐TA) spectroscopy. These combined effects collectively result in significantly enhanced CH4 formation performance. This work highlights the potential of regulating catalytic sites in immiscible metal combinations for photo‐thermal catalytic CO2 conversion, underscoring the promise of these cost‐effective alloys in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Processes that integrate the capture and conversion of CO 2 using dual-function materials (DFMs) exhibit high potential to alleviate global warming. This study reports the numerical analysis of the unsteady-state mass transfer and reactions that occur during CO 2 capture and its hydrogenation to methane in a fixed-bed reactor packed with the DFM (15 wt%Na 2 CO 3 /10 wt%Ni/Al 2 O 3). This study uses thermogravimetric analysis to estimate the reaction rate of the DFM, which is used to predict the mass transfer throughout the reactor. The simulation generally represents the experimental behavior of the reactor fed CO 2 /N 2 and H 2 in sequence. Additionally, the hydrogen flow rate significantly influenced the concentration of the product. The theoretical analysis of the concentration distribution of the chemical species inside the reactor indicates that hydrogen supplied at a low flow rate facilitates the long-term recovery of high concentrations of the product. The results of this study could expedite the practical application of DFM-based processes. • Simulations on a process integrating CO 2 capture and hydrogenation were conducted. • A fixed-bed reactor packed with a dual-function material was analyzed. • Data based on thermogravimetric analysis were used for the numerical analysis model. • Experiments of the reactor fed CO 2 /N 2 and H 2 were well represented by simulations. • Changes in gas composition inside the reactor and at the outlet were predicted. [ABSTRACT FROM AUTHOR]

CO 2 methanation involves the utilization of renewable hydrogen, greenhouse gases CO 2 as raw materials to transform them into clean energy sources in the form of methane. This procedure is of great significance for conserving energy and reducing emissions. In this study, a series of Ni/ZSM-5 catalysts with different Si/Al ratios were prepared. H 2 -TPR and XPS were employed to explore the influence of Al content on the properties of the Ni species. The adsorption properties of the reactants on the different Ni/ZSM-5 catalysts were investigated by CO 2 -TPD and H 2 -TPD. Moreover, as H 2 O is produced during the reaction, contact angle measurement were conducted to investigate the hydrophilicity and hydrophobicity of the samples. It is suggested that the ZSM-5 Si/Al ratio (or Al content) affected both Ni dispersion and catalyst hydrophilicity. The higher Al content in ZSM-5 improved Ni dispersion. However, high hydrophilicity is unfavorable for product removal, leading to poor catalytic performance. As a result, the Ni/ZSM-5 (41) sample with appropriate Si/Al exhibited good catalytic performance with CO 2 conversion of 64 % and CH 4 selectivity of >98 % at 350 °C. The CO 2 conversion and CH 4 selectivity remained at the initial level after reaction for 72 h. This indicates that the Ni/ZSM-5 (41) catalyst has excellent stability. Based on the characterization after the reaction, it can be observed that the catalyst exhibits good carbon deposition resistance and stability. Therefore, the choice of zeolite acid amount is crucial for the reaction performance. This study will provide guideline for the development of high-performance catalysts for CO 2 methanation-loaded Ni. [Display omitted] • The effect of Si/Al ratios on CO 2 methanation over Ni/ZSM-5 was investigated. • The higher Al content in ZSM-5 improved Ni dispersion. • High hydrophilicity is unfavorable for product removal, leading to poor activity. • Ni/ZSM-5 sample with appropriate Si/Al is benefit for good catalytic performance. [ABSTRACT FROM AUTHOR]

Sugarcane bagasse carbon (SCBC) was synthesized and used to support NiCoP/CoP 2 nanoparticles (NiCoP/CoP 2 -SCBC), and its electrocatalytic performance for the hydrogen evolution reaction (HER) was investigated and compared with that of NiCoP/CoP 2 nanoparticles and NiCoP/CoP 2 nanoparticles supported on carbon black (NiCoP/CoP 2 -C). Impressively, NiCoP/CoP 2 -SCBC shows the best electrocatalytic performance for HER with an over-potential of 159.5 mV at 10 mA cm-2 and a Tafel slope of 67.24 mV dec-1, along with the excellent stability. This outstanding performance is partly attributed to the abundant hydroxyl functional groups in SCBC, which can make the catalyst have better dispersion and a higher proportion of Ni2+. In addition, SCBC can lead to more defects in NiCoP/CoP 2 , and SCBC contains a large number of P elements, which can increase the catalytic active sites and contribute to the fast HER process to some degree. • The NiCoP/CoP 2 -SCBC composite catalyst was prepared by a calcination method. • NiCoP/CoP 2 -SCBC shows superior electrocatalytic activity for HER in acid solution. • The high catalytic activity of NiCoP/CoP 2 -SCBC is due to the abundant –OH in SCBC. • More defects caused by SCBC and its rich P content also contribute to the activity. • NiCoP/CoP 2 -SCBC has excellent long-term stability besides high catalytic activity. [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]

In photocatalysis, the resulted heat by the relaxation of most of incident light no longer acts as the industrially favorite driving force back to the target photo‐reaction due to more or less the negative relation between photocatalytic efficiency and temperature. Here, we reported a visible light‐sensitized protocol that completely reversed the negatively temperature‐dependent efficiency in photo‐driven CO2 methanation with saturated water vapor. Uniform Pt/N‐TiO2/PDI self‐assembly material decisively injects the excited electron of PDI sensitizer into N‐TiO2 forming Ti−H hydride which is crucially temperature‐dependent nucleophilic species to dominate CO2 methanation, rather than conventionally separated and trapped electrons on the conductor band. Meanwhile, the ternary composite lifts itself temperature from room temperature to 305.2 °C within 400 s only by the failure excitation upon simulated sunlight of 2.5 W/cm2, and smoothly achieves CO2 methanation with a record number of 4.98 mmol g−1 h−1 rate, compared to less than 0.02 mol g−1 h−1 at classic Pt/N‐TiO2/UV photocatalysis without PDI sensitization. This approach can reuse ~53.9 % of the relaxed heat energy from the incident light thereby allow high‐intensity incident light as strong as possible within a flowing photo‐reactor, opening the most likely gateways to industrialization. [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]

The characteristic behavior of the wall exerts a strong influence on the flame acceleration (FA) and deflagration-to-detonation transition (DDT) processes in microchannels [Ramachandran et al., "A numerical investigation of deflagration propagation and transition to detonation in a microchannel with detailed chemistry: Effects of thermal boundary conditions and vitiation," Phys. Fluids 35, 076104 (2023)]. In this work, motivated by the catalytic microcombustors in realistic industrial settings, we study the influence of catalytic nickel walls on the FA & DDT processes. Highly resolved numerical simulations (spanning 10–20 grid points across the flame thickness) are performed, employing a 9-species 21-reaction combustion mechanism for H2-combustion by Li et al. ["An updated comprehensive kinetic model of hydrogen combustion," Int. J. Chem. Kinet. 36, 566–575 (2004)] for the gas-phase chemistry and a 5-species 12-reaction submechanism derived from a methanation microkinetic mechanism by Schmider et al. ["Reaction kinetics of CO and CO2 methanation over nickel," Ind. Eng. Chem. Res. 60, 5792–5805 (2021)] for the catalytic surface chemistry. Stoichiometric H2/air with and without 25% (by mole) of H2O dilution/vitiation are investigated. The simulations demonstrate that catalytic walls enhance flame propagation in the vitiated mixture (which exhibits lower flame speeds) by providing additional radical production and heat release at the surface. As a result, the traditionally observed parabolic-like flame front profile in microchannels inverts due to preferential propagation of the flame along the wall. In contrast, the unvitiated mixture exhibits rapid flame acceleration, and the influence of catalytic walls is found to be minimal. These observations are due to the fact that the residence time available for coupling the heterogeneous wall chemistry with the gas-phase combustion is smaller at higher flame speeds (in unvitiated mixtures). [ABSTRACT FROM AUTHOR]

In this study, we conducted a comparative analysis of the catalytic behavior of Ni-CaO-Al2O3 dual functional material (DFM) and a physical mixture of Ni-Al2O3 and CaO-Al2O3 in the integrated carbon capture methanation (ICCM) process for promoted methane production. H2-temperature-programmed surface reaction (H2-TPSR) analysis revealed that in Ni-CaO-Al2O3 DFM, CO2 adsorbed on the CaO surface can spillover to metallic Ni surface, enabling direct hydrogenation without desorption of CO2. Ni-CaO-Al2O3 DFM exhibited a rapid initial methanation rate due to CO2 spillover. The Ni-CaO-Al2O3 DFM, with Ni and CO2 adsorption sites in close distance, allows efficient utilization of the heat generated by methanation to desorb strongly adsorbed CO2, leading to enhanced methane production. Consequently, Ni-CaO-Al2O3 DFM produced 1.3 mmol/gNi of methane at 300 °C, converting 35% of the adsorbed CO2 to methane. [ABSTRACT FROM AUTHOR]

Several Cu and Ni-based catalysts were synthetized over Ce-based supports, either pure or mixed with different amounts of alumina (1:2 and 1:3 mol/mol). Different metal loadings (10–40 wt%) and preparation methods (wet impregnation, co-precipitation, and flame-spray pyrolysis—FSP) were compared for the oxidative steam reforming of methanol. Characterization of the catalysts has been performed, e.g., through XRD, BET, XPS, TPR, SEM, and EDX analyses. All the catalysts have been tested in a bench-scale continuous setup. The hydrogen yield and methanol conversion obtained have been correlated with the operating conditions, metal content, crystallinity of the catalyst particles, total surface area, and with the interaction of the metal with the support. A Cu loading of 20% wt/wt was optimal, while the presence of alumina was not beneficial, decreasing catalyst activity at low temperatures compared with catalysts supported on pure CeO2. Ni-based catalysts were a possible alternative, but the activity towards the methanation reaction at relatively high temperatures decreased inevitably the hydrogen yield. Durability and deactivation tests showed that the best-performing catalyst, 20% wt. Cu/CeO2 prepared through coprecipitation was stable for a long period of time. Full methanol conversion was achieved at 280 °C, and the highest yield of H2 was ca. 80% at 340 °C, higher than the literature data. [ABSTRACT FROM AUTHOR]

Methanation, the process of producing methane from CO2 and hydrogen via renewable energy sources, has attracted considerable attention. However, reducing the hydrogen content in the product methane gas remains a challenge for using this product gas as a city gas. To overcome this challenge, this study investigated the ethanol dehydration–hydrogenation reaction (C2H5OH + H2 → C2H6 + H2O) using ethanol, which is widely used as a biofuel, and hydrogen in the product methane gas. The reactions were performed under practical conditions using Pd and solid acid catalysts. It was confirmed that ethanol could be converted to ethane in high yields while the hydrogen content is reduced in the methane-rich gas. This study demonstrates the practical applicability of the ethanol dehydration-hydrogenation reaction to the methanation process to generate city gas. [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 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]

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]

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]

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]