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This study investigates the effect of cerium–zirconium supported nickel catalyst (Ni/CeZr(x)) on the dry reforming reaction of methane (CH4) and carbon dioxide (CO2) to produce hydrogen (H2) and carbon monoxide (CO) for use in petrochemical processes. CeZr supports were synthesized via template-assisted co-precipitation using CTAC as a template with varying pH values (5, 7, 8.5, and 10) and underwent hydrothermal processing. Nickel (10% by weight) was then loaded onto the support through incipient wetness impregnation. The dry reforming reaction was performed at 700 °C. Results revealed that as the pH increased from acidic to basic conditions, the precipitation and integration of ZrO2 and CeO2 improved, leading to the formation of CeZr(x) composite supports. The Ce/Zr ratio in Ni/CeZr(x) catalysts influenced the generation of oxygen vacancies (OV) on the catalyst surface, affecting CO2 and CH4 conversions and the H2/CO ratio. The Ni/CeZr(8.5) catalyst exhibited the highest activity and stability due to its high surface oxygen vacancy and the number of basic sites on the CeZr(8.5) surface. Moreover, this catalyst reduced coke formation by promoting CO2 adsorption and dissociation, which facilitated the formation of surface-bound oxygen species that reacted with the surface carbon species. [ABSTRACT FROM AUTHOR]

Catalysts based on Ni and Fe nanoparticles deposited selectively on carbon nanotubes were investigated before and after the dry methane reforming. Three catalysts were synthesized and evaluated, varying the concentration of Ni inside and Fe outside the carbon tubes. BET analysis revealed that the acid treatment opened the ends of the nanotubes and resulted in a higher surface area. Transmission electron microscopy (TEM) showed 24 layers with inner diameter ranging from 4 to 6 nm and outer diameter ranging from 16 to 22 nm. Raman spectroscopy confirmed that after calcination at high temperature the structure of the nanotubes was maintained. X-ray diffraction (XRD) analysis of the catalysts confirmed the presence of NiO (2.6–3.2 nm) and Fe2O3 (4.3 nm) crystallites. The catalytic tests presented high activity in dry methane reform (DRM). The catalysts 10Ni@CNT and 10Ni@CNT/5Fe presented conversions of CH4 (63 and 67%) and CO2 (72 and 88%), respectively, at 800 °C, under atmospheric pressure. Analysis after the reaction showed an increasing ratio of ID/IG, which indicates the formation of defects. The Raman analysis showed that even after calcination at high temperatures the structures of the nanotubes were mostly preserved, and TEM images showed that during the reaction, there were formation of nanotubes occurring randomly. [ABSTRACT FROM AUTHOR]

We investigate a species and energy conversion process applied in an internal combustion engine. CO 2 and CH 4 is converted to synthesis gas (CO and H 2). This reaction is endothermic and in addition requires high temperatures. The temperature is increased via compression and a parallel exothermic reaction. We investigate this process with the aim of obtaining dependencies of the initial conditions on the CO 2 conversion, as well as finding optimal conditions under which CO 2 is converted and mechanical work is delivered. The dependencies of the initial conditions are investigated using two methods, a) a large parametric study; b) optimal conditions are found using a genetic algorithm that optimizes the CO 2 conversion as target function. It was found that the gas mixture composition has the largest influence on the CO 2 conversion, if there is a parallel partial oxidation of CH 4 and DME (as a reaction enhancer) to CO and H 2. During the investigations, we found initial conditions in which up to 55% of the initial CO 2 was converted, in combination with work output. The best results were found for fuel-rich conditions (ϕ = 2.5 to 3.5); argon concentration, heat losses and initial temperature showed a minor influence. We found that ignition must occur to reach the high temperatures required to convert large amounts of CO 2. A suitable choice of the initial gas, CO 2 is converted throughout the entire process, despite the (partial) oxidation of the fuel. [ABSTRACT FROM AUTHOR]

Abstract Finding a robust catalytic system for hydrogen production via dry reforming of methane (DRM) remains a challenge. Herein, MNi0.9Zr1−xYxO3 (M = Ce, La, and La0.6Ce0.4; x = 0.00, 0.05, 0.07, and 0.09) catalyst was prepared by the sol–gel method, tested for DRM and characterized by surface area and porosity, X‐ray diffraction, H2‐temperature programmed reduction, thermogravimetry, and transmission electron microscopy. In La0.6Ce0.4NiO3 catalyst, the substitution of Ni by 0.1% Zr results in a constant high catalytic activity (83% hydrogen yield at 800°C) due to the presence of reducible “NiO‐species interacted strongly with the support” (stable metallic Ni over reduced catalyst) and redox input by ceria phase for laying instant lattice oxygen during lag‐off period of CO2. Substitution of Ni by Zr and Y in the CeNiO3 catalyst system nurtures Ni3Y (providing highly stable metallic Ni for CH4 decomposition) and cerium yttrium oxide phases (providing strong redox input). CeNi0.9Zr0.01Y0.09O3 shows 85% H2 yield at 800°C.

In this study, vermiculite was explored as a support material for nickel catalysts in two key processes in syngas production: dry reforming of methane with CO2 and steam reforming of ethanol. The vermiculite underwent acid or base treatment, followed by the preparation of Ni catalysts through incipient wetness impregnation. Characterization was conducted using various techniques, including X-ray diffraction (XRD), SEM–EDS, FTIR, and temperature-programmed reduction (H2-TPR). TG-TD analyses were performed to assess the formation of carbon deposits on spent catalysts. The Ni-based catalysts were used in reaction tests without a reduction pre-treatment. Initially, raw vermiculite-supported nickel showed limited catalytic activity in the dry reforming of methane. After acid (Ni/VTA) or base (Ni/VTB) treatment, vermiculite proved to be an effective support for nickel catalysts that displayed outstanding performance, achieving high methane conversion and hydrogen yield. The acidic treatment improved the reduction of nickel species and reduced carbon deposition, outperforming the Ni over alkali treated support. The prepared catalysts were also evaluated in ethanol steam reforming under various conditions including temperature, water/ethanol ratio, and space velocity, with acid-treated catalysts confirming the best performance.

The properties of supports (such as oxygen vacancies, oxygen species properties, etc.) significantly impact the anti-carbon ability due to their promotional effect on the activation of CO2 in dry reforming of methane (DRM). Herein, pyrochlore-type La2Ce2O7 compounds prepared using co-precipitation (CP), glycine nitrate combustion (GNC) and sol–gel (S-G) methods, which have highly thermal stability and unique oxygen mobility, are applied as supports to prepare Ni-based catalysts for DRM. The effect of the calcining temperature (500, 600 and 700 °C) on La2Ce2O7(CP) has also been investigated. Based on multi-technique characterizations, it is found that the synthesis method and calcination temperature can influence the particle size of the La2Ce2O7 support. Changes in particle size strongly modulate the pore volume, specific surface area and numbers of surface oxygen vacancies of the La2Ce2O7 support. As a result, the distribution of supported Ni components is affected due to the different metal–support interaction, thereby altering the activity of the catalysts for cracking CH4. Moreover, the supports’ abilities to adsorb and activate CO2 are also adjusted accordingly, accelerating the removal of the carbon deposited on the catalysts. Finally, La2Ce2O7(CP 600) with an appropriate particle size exhibits the best catalytic activity and stability in DRM.

[Display omitted] The effect of the support nature (SiO 2 , Al 2 O 3 , SiO 2 –Al 2 O 3) on the catalytic performance of Ni-based catalysts prepared by the incipient wetness method was explored in the dry reforming of methane reaction, and the catalysts were characterized by TG-DTA, SEM-EDX, XRD and UV-VIS methods. The results demonstrate that NiO supported on SiO 2 -modified Al 2 O 3 exhibits superior catalytic performance in methane dry reforming in the temperature range of 650–700 °C. [ABSTRACT FROM AUTHOR]

A one-pot hydrothermal technique was used to make a series of Ti-incorporated mesoporous SBA-15 with varying Si/Ti ratios. The synthesized mesoporous materials were modified by introducing Ni (9%) as active metal and Pt (0.5%) as promoter using nickel nitrate and chloroplatinic acid, respectively, as metal precursors through incipient wetness impregnation method. All the catalysts and supports were characterized by X-ray diffraction, BET surface area, Fourier Transform–Infrared spectroscopy, UV–Visible diffuse reflectance spectroscopy, H 2 –temperature-programmed reduction, NH 3 –temperature-programmed desorption, transmission electron microscopy, and thermogravimetric analysis. The catalysts were subjected to dry reforming of methane using CH 4 /CO 2 (molar feed ratio of 1:1) with a gas hourly space velocity (GHSV) of 36,000 mL. g−1. h−1 at a temperature range of 400–800 °C. The characterization results confirmed the incorporation of titanium ions in the SBA-15 matrix. However, Si/Ti loadings of 10 and 20 exhibited low extra-framework anatase phase titania levels, and high surface acidity. Among the subjected catalysts, Pt–Ni/Ti-SBA-15 (Si/Ti = 10) showed higher catalytic activity (CH 4 = 84% and CO 2 = 91%) with a H 2 /CO ratio of 3.6 after an 8 h reaction, and exhibited higher stability and coke tolerance than the bare catalysts and other modified Pt–Ni/Ti-SBA-15 catalysts. The characterization results of spent catalysts also confirmed low coke deposition on titanium-incorporated catalysts. The remarkable performance of the Pt–Ni/Ti-SBA-15 towards CH 4 conversion and CO 2 conversion may be related to strong metal–support interaction, presence of strong and weak acid sites, well-dispersed active metals and bi-metallic interaction. [Display omitted] • Ti4+ incorporation in Pt–Ni/SBA-15 increased the conversion of CH 4 and CO 2 for DRM. • Pt–Ni/Ti-SBA-15 catalysts were more active and stable than Pt–Ni/SBA-15 catalyst. • Addition of Ti and Pt in Ni/SBA-15 showed high resistance towards coke formation. • Pt–Ni/Ti-SBA-15 (10) showed maximum conversion, stability and least coke deposition. [ABSTRACT FROM AUTHOR]

In recent years, the greenhouse effect has emerged as a major environmental concern. As a result, the utilization and capture of greenhouse gases have become urgent tasks. The dry reforming of methane (DRM) reaction is a technology that directly converts greenhouse gases (CH4 and CO2) into valuable products. Ni-based catalysts have gained significant attention and industrial prospects in DRM reactions due to their excellent performance and cost-effectiveness compared to noble metals. However, challenges such as metal sintering and carbon deposition hinder its industrialization. This paper provides a review of the recent advancements in catalyst design for DRM reactions, with a focus on the impact of additives, supports, and preparation methods on Ni-based catalysts. It also describes the reaction and deactivation mechanisms, as well as the thermodynamics and kinetics of DRM reactions. Furthermore, this paper envisions the main challenges and opportunities associated with Ni-based catalysts in DRM research. [ABSTRACT FROM AUTHOR]

Dry reforming of methane is a very appealing catalytic route biogas (mainly composed by greenhouse gases: carbon dioxide and methane) conversion into added value syngas, which could be further upgraded to produce liquid fuels and added value chemicals. However, the major culprits of this reaction are coking and active phase sintering that result in catalysts deactivation. Herein we have developed a highly stable bimetallic Ni–Rh catalyst supported on mixed CeO 2 –Al 2 O 3 oxide using low-noble metal loadings. The addition of small amounts of rhodium to nickel catalysts prevents coke formation and improves sintering resistance, achieving high conversions over extended reaction times hence resulting in promising catalysts for biogas upgrading. [Display omitted] • H 2 -rich syngas can be obtained efficiently from biogas reforming. • Ni-based catalysts are deactivated by metal sintering and coke deposition. • Doping with low Rh loadings deactivation can be successfully prevented. [ABSTRACT FROM AUTHOR]

This work presents the development of an A-site deficient La 0.9−x Ba x Al 0.85 Ni 0.15 O 3 (x = 0, 0.02, 0.04, and 0.06) perovskite oxide catalyst for dry reforming of model biogas. The catalysts are prepared using a citrate sol-gel method and used for biogas dry reforming at 800 °C for feed ratios (CH 4 /CO 2) of 1.5 and 2.0. The fresh and spent catalysts are analyzed using XRD, FTIR, TPD, XPS, FESEM, TEM, TPR, TGA-DTA, and Raman analysis. The XRD analysis exhibits the host perovskite oxide structure and the exsolved Ni phase for all prepared catalysts. The partial doping of Ba improves the metal support interaction and oxygen vacancies that enhance catalytic activity and stability, as revealed by the TPR and XPS analysis. The stability experiment on La 0.9−x Ba x Al 0.85 Ni 0.15 O 3 , for x = 0 catalyst resulted in reduced activity due to the catalyst deactivation by sintering, as confirmed by XRD and FE-SEM. Among all the catalysts studied, La 0.84 Ba 0.06 Al 0.85 Ni 0.15 O 3 (LB6AN-15) exhibited the highest catalytic stability with CH 4 , and CO 2 conversions are 60% and 93%, respectively, for 40 h time-on-stream due to the strong metal support interactions, high oxygen vacancies, and anti-sintering of exsolved Ni nanoparticles in biogas dry reforming. [Display omitted] • Biogas dry reforming over Ni and Ba co-doped La 0.9 AlO 3 perovskite catalysts is carried out. • Fresh and spent catalysts retained their host perovskite structure. • An increase in the Ba loading enhances the metal support interaction. • The LB6AN-15 catalyst displayed high activity and stability in 40 h biogas dry reforming. [ABSTRACT FROM AUTHOR]

Fuel flexibility is one of the significant advantages of solid oxide fuel cells (SOFCs). The utilization of methane in SOFCs can not only reduce fuel costs, but also greatly expand its application scenarios, which is of great significance to the commercial development of SOFCs. However, when methane is directly used, Ni-based cermet anode suffers from coking, which seriously affects the durability of the cell. To alleviate the coking issue, a reforming layer outside the Ni-based anode-supporter was proposed in this study, and Ba 0.9 (Zr 0.8 Y 0.2) 1- x Ni x O 3-δ (BZYNi x , x = 0.05, 0.1, 0.15 and 0.2) was used as reforming layer material. Among BZYNi x catalysts, BZYNi 0.2 exhibited excellent catalytic activity toward dry reforming of methane, and methane conversion was as high as 85% at 750 °C. The excellent catalytic durability and coking-resistance of BZYNi 0.2 were also confirmed. When BZYNi 0.2 reforming layer was applied, the single cell fueled with CH 4 –CO 2 fuel showed significantly improved electrochemical performance, durability and coking-resistance. The utilization of BZYNi 0.2 reforming layer provides guidance for solving the coking issue of SOFC cermet anodes when fueled with hydrocarbon. • DRM catalytic activities of BZYNi x with different Ni doping content was explored. • A Ba 0.9 (Zr 0.8 Y 0.2) 0.8 Ni 0.2 O 6-δ reforming layer was added outside the anode support. • Enhanced performance and durability of RSC were observed when fueled with CH 4 –CO 2. [ABSTRACT FROM AUTHOR]

Ever-increasing CO2 emissions and atmospheric concentration mainly due to the burning of traditional fossil fuels have caused severe global warming and climate change problems. Inspired by nature's carbon cycle, we propose a novel dual functional catalyst-sorbent to tackle energy and environmental problems simultaneously via direct capture of CO2 from air and in-situ solar-driven conversion into clean fuels. Economically and operationally advantageous, the planned coupling reaction can be carried out in a single reactor without the requirement for an extra trapping device. The great CO2 capture and conversion performance in an integrated step is shown by the CO2 capacity of up to 0.38 mmol·g−1 for adsorption from 500 ppm CO2 at 25 °C and the CO2 conversion rate of up to 95%. Importantly, the catalyst-sorbent is constituted of a nonprecious metal Ni catalyst and an inexpensive commercially available CO2 sorbent, viz, zeolite NaA. Furthermore, this designed dual functional material also exhibits outstanding stability performance. This work offers a novel pathway of capturing CO2 in the air at room temperature and converting it by CH4 into fuel, contributing to the new era of carbon neutrality. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of active and stable nickel catalysts for methane dry reforming based on Pr-doped ceria–zirconia obtained via the solvothermal continuous method. Studies on the physicochemical and catalytic properties of the 5%Ni/Ce0.75Zr0.25−xPrxO2 series have showed that Pr introduction leads to an increase in the amount of highly reactive oxygen in the oxide lattice. Praseodymium-based catalysts showed significantly higher reactant conversions. In addition to the nature of support, the method of nickel introduction was also studied; Ni was added both using impregnation and the one-pot procedure with mixed oxide preparation. The method of Ni addition was shown to have significant effect on the morphology of its particles and Ni-support interaction, and, respectively, on catalytic activity and coking stability. The 5%Ni/Ce0.75Zr0.15Pr0.1O2 catalyst prepared by one-pot method showed stable operation in the MDR reaction for 30 h at CO2 and CH4 conversions of ~40% and an H2 yield of ~18% (T = 700 °C, τ = 10 ms). [ABSTRACT FROM AUTHOR]

Citric acid, one of the representative chelate compounds, has been widely used as an additive to achieve the highly dispersed metal-supported catalysts. This study aimed to investigate the effect of citric acid concentration on the preparation of the highly dispersed Ni catalysts on mesoporous silica (SBA-15) for the dry reforming of methane. A series of Ni/SBA-15 catalysts with citric acid were prepared using the acid-assisted incipient wetness impregnation method, and the Ni/SBA-15 catalyst as a reference was synthesized via the impregnation method. First of all, the citric acid addition during the catalyst synthesis step regardless of its concentration resulted in highly dispersed Ni particles of ~4–7 nm in size in Ni/SBA-15 catalysts, which had a superior and stable catalytic performance in the dry reforming of methane (93% of CO2 conversion and 86% of CH4 conversion). In addition, the amount of coke formation was much lower in a series of Ni/SBA-15 catalysts with citric acid (~2–5 mgcoke gcat−1 h−1) compared to pristine Ni/SBA-15 catalysts (~22 mgcoke gcat−1 h−1). However, when the concentration of citric acid became higher, the more free NiO species that formed on the SBA-15 support, leading to large Ni particles after the stability test. The addition of citric acid is a very clear strategy for making highly dispersed catalysts, but its concentration needs to be carefully controlled. [ABSTRACT FROM AUTHOR]

A thermodynamic model is developed using a one-dimensional model, LOGEcat to understand the dry reforming of methane over nickel-based catalysts. To do so, we have extended our previously developed mechanism (Rakhi and Shrestha in React Kinet, Mech Catal 135:3059–3083, 2022) which contains 21 reversible reactions by adding 5 more reversible reactions and updating the thermochemistry of one intermediate species. The adjusted mechanism contains 26 reversible reactions obtained with the help of thermodynamic analysis. This study focuses on using the thermodynamic model for dry reforming of methane and insights into the reaction pathways and sensitivity analysis for the kinetically consistent surface reaction mechanism. The applicability of the mechanism is examined for reactor conditions in terms of parameters such as temperature by comparing the results with the available reference data. The mechanism is able to accurately express the reforming conditions of methane over the nickel catalyst for complete range of temperature and also provide useful insights into the reaction pathways established with the thermodynamic model. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) utilization and conversion, as one of the main parts of carbon capture, utilization, and storage (CCUS), is not only considered an important way to mitigate global warming but also an attractive industrial route to produce valuable fuels and chemical feedstocks. Catalytic dry reforming of methane (DRM) is a promising technology for carbon dioxide utilization and conversion as it can produce syngas, carbon monoxide (CO), and hydrogen (H2) for widespread industrial production processes. In most studies of the DRM reaction, a relatively high operational temperature (i.e., >700°C) has been applied since the reactivity limitation of widely used Ni‐based catalysts at low temperatures and the extremely endothermic property of the DRM reaction. However, high cost and high requirement of thermal stability for catalysts have become a severe problem impeding the further commercialization of DRM technology. Decreasing the operational temperature (i.e., <700°C) is considered a promising way for further application of the DRM route to convert CO2 and produce syngas. However, traditional Ni‐based catalysts suffered from unsatisfied reactivity and severe coke formation, leading to quick deactivation at low temperatures. Developing a catalyst with excellent catalytic activity, coke resistance, and improved thermal stability is necessary for low‐temperature DRM reactions. In recent years, with significant development in materials, catalyst design, and computational simulation, some synthesized catalysts have achieved considerable improvement in catalytic performance in low‐temperature DRM. Hence, a review of recent development on low‐temperature DRM catalysts is provided here to further guide and profoundly understand catalyst design for low‐temperature DRM. [ABSTRACT FROM AUTHOR]

Mixed Ce−Zr oxides with a fluorite structure were synthesized by the solvothermal method in a supercritical medium of isopropanol. The prepared mixed oxides Ce0.5Zr0.5O2 and Ce0.75Zr0.25O2 were used as supports for 5 wt%Ni and bimetallic 2.5 wt%Ni+2.5 wt%Co catalysts. The catalysts were fully characterized (specific surface area, morphology, particle size, phase composition, surface atomic composition) and tested in ethanol dry reforming. The dependences of the conversion of C2H5OH and CO2, the yield of CO and H2, and the H2/CO ratio were estimated. The effect of the supported metals interaction and the effect of Ce/Zr ratio in the support on the catalytic activity were shown. The presence of nickel in the composition of the catalyst is necessary for high catalytic activity. It has been shown that the addition of cobalt cannot contribute to increase the catalytic activity and stability, but helps to decrease the deposition of carbon and significantly reduces the rate of carbon formation during ethanol dry reforming comparing to the monometallic nickel material. [ABSTRACT FROM AUTHOR]

Different promoters have a significant impact on the catalyst performance. In this paper, the effects of different promoters on the physical properties and catalytic behavior of methane dry reforming catalysts were investigated. A series of characterizations showed that the Mg, Ba, and Ca promoters increased the basicity of the catalysts. However, their high concentration of OH− leads to the destruction of Ni3Si2O5(OH)4 species, which results in a decrease of catalytic performance. The addition of Ce significantly improves the catalyst stability. After 100 h of Ni‐5Ce‐MSC reaction, there was almost no carbon deposition, exhibiting high activity and resistance to carbon accumulation. These findings provide a new perspective for the design of nickel‐based dry reforming catalysts. [ABSTRACT FROM AUTHOR]

Ni supported on the ordered mesoporous Ce x Zr 1−x O 2 with various Ce/Zr molar ratios prepared by a programmed evaporation-induced self-assembly method were employed for dry reforming of methane. The systematical techniques, including X-ray diffraction, N 2 physisorption, Raman, transmission electron microscope, chemisorption, X-ray photoelectron spectroscopy, diffuse reflection Fourier transform infrared spectrum, thermogravimetric analysis, etc. were used to clarify the structure-activity relationship. It was found that the prepared catalysts all had highly ordered mesoporous structures, and compared to the sole ZrO 2 and CeO 2 , the CeO 2 -ZrO 2 composites exhibited the best thermal stability, stronger basicity, and greater oxygen migration. Especially, the composite with Ce/Zr ratio of 1/4 possessed the suitable basicity and most oxygen vacancies, which were closely related to the excellent anti-carbon ability. Moreover, its supported catalyst had the strongest metal-support interaction and highest Ni dispersion. Expectedly, the catalyst showed the superior activity and the robust stability for at least 1800 min [Display omitted] • Ce x Zr 1−x O 2 were prepared by programmed evaporation-induced self-assembly method. • Composites had higher thermal stability, stronger basicity, greater oxygen migration. • C1Z4 possessed suitable basicity, most oxygen vacancies, highest anti-carbon ability. • NC1Z4 showed the superior activity and the long-term stability. [ABSTRACT FROM AUTHOR]

Nickel is a well-known catalyst in hydrogenation and dehydrogenation reactions. It is currently used in industrial processes as a homogenous and heterogeneous catalyst. However, to reduce the cost and increase the efficiency of catalytic processes, the development of single-atom catalysts (SACs) seems promising. Some SACs have already shown increased activity and stability as compared to nanoparticle catalysts. From year to year, the number of reports devoted to nickel SACs is growing rapidly. Among them, there are very few articles devoted to thermal catalysis, but at the same time, this subject is important. Thus, this review discusses recent advances in the synthesis, structure, and application of nickel SACs, mainly in catalytic hydrogenation/dehydrogenation reactions and in the dry reforming of methane. The collected and analyzed data can be useful in the development of novel nickel SACs for various processes. [ABSTRACT FROM AUTHOR]

Mesoporous Ni/La2O3/γ-Al2O3 catalysts with different La contents (0, 0.5, 1.5, 2.5, 3.5, and 4.5 wt.%) were prepared by the step-by-step impregnation method. The physicochemical properties of the prepared Ni/La2O3/γ-Al2O3 catalysts were characterized by H2-TPR, XRD, BET, O2-TPO, and TG. The effect of La dosage on the catalytic performance of Ni/γ-Al2O3 catalyst for dry reforming of methane was further investigated. The results show that the La content has a significant effect on the reducibility of high-valence Ni species, specific surface area, pore size, and pore volume as well as the catalytic performances. The high-valence Ni species in the NL3.5A catalyst precursor has high reducibility. And the specific surface area, pore size and pore volume of the NL3.5A catalyst are 145.9 m2 g−1, 11.7 nm, and 0.47 cm3 g−1, respectively. The catalytic activity of the series of prepared mesoporous Ni/La2O3/γ-Al2O3 catalysts follows the order: NL3.5A > NL2.5A > NL4.5A > NL1.5A > NL0.5A > NL0A. Namely, the NL3.5A catalyst possesses the best catalytic activity. The CH4 and CO2 conversions of NL3.5A catalyst are 61.6 and 39.1% at 600 °C, respectively. Additionally, it maintains a superior recycle capability for dry reforming of methane reaction because of the high coke resistance compared with the Ni/γ-Al2O3 catalyst. [ABSTRACT FROM AUTHOR]

Nanofibrous KCC-1 supported Ni–Co bimetallic catalysts were investigated for dry reforming of methane for syngas generation. Monometallic catalysts such as Ni/KCC-1 and Co/KCC-1, and a series of bimetallic Ni–Co/KCC-1 catalysts were prepared by impregnation and co-impregnation method, respectively. All the catalysts were characterized by XRD, FT-IR, HR-SEM, FE-SEM, XPS, FT-Raman, BET, UV–Visible DRS and AAS techniques. Monometallic nickel supported catalyst contains NiO as an active phase, whereas bimetallic nickel catalysts contain Ni 2 O 3 , and NiCo 2 O 4 on the surface. In the case of cobalt loaded catalysts, spinel Co 3 O 4 is the dominant active species, apart from NiCo 2 O 4. The addition of cobalt in Ni/KCC-1 has a pronounced effect on the crystallite size, surface area and active species. The hydrogen pretreatment of the catalyst produces bimetallic Ni–Co alloy on the surface. The catalytic activities of the bimetallic catalysts towards dry reforming of methane are better than monometallic catalysts. Mesoporous silica-based KCC-1 offers easy accessibility to the entire surface moieties due to its fibrous nature and the presence of channels, instead of pores. The 2.5%Ni-7.5%Co/KCC-1 showed the maximum CH 4 and CO 2 conversion along with a remarkably low H 2 /CO ratio. The life-time test confirms the high thermal stability of the catalysts at 700 °C for 8 h, with less deactivation due to coke formation. The spent catalysts were characterized by XRD, TGA, FT-Raman, and FE-SEM to understand the structural and chemical changes during the reaction. The insignificant D band and G band of graphitic carbon in FT-Raman spectra for the highly active 2.5%Ni-7.5%Co/KCC-1 and 5%Ni–5%Co/KCC-1 catalysts along with TGA results containing 12% weight loss confirms the minimum coke deposition, formation of amorphous carbon and highest coke resistance. The fibrous support restricts the sintering and aggregation of nickel particles as well the deposition of coke. The addition of amphoteric cobalt increases the activity and stability of the catalysts. Ni–Co/KCC-1 with high coke resistance seems to be a promising catalyst for dry reforming of methane. [Display omitted] • Ni–Co/KCC-1 was synthesized by sol–gel-hydrothermal and co-precipitation method. • Cobalt addition in Ni/KCC-1 catalyst suppressed the aggregation of Ni particles. • Bimetallic Ni–Co/KCC-1 catalysts are more coke resistant than monometallic KCC-1. • 2.5%Ni-7.5%Co/KCC-1 showed the highest CH 4 and CO 2 conversion, and a low H 2 /CO ratio. • Bimetallic catalysts improved the catalytic performance by reducing coke deposition. [ABSTRACT FROM AUTHOR]

Finding a robust catalytic system for hydrogen production via dry reforming of methane (DRM) remains a challenge. Herein, MNi0.9Zr1−xYxO3 (M = Ce, La, and La0.6Ce0.4; x = 0.00, 0.05, 0.07, and 0.09) catalyst was prepared by the sol–gel method, tested for DRM and characterized by surface area and porosity, X‐ray diffraction, H2‐temperature programmed reduction, thermogravimetry, and transmission electron microscopy. In La0.6Ce0.4NiO3 catalyst, the substitution of Ni by 0.1% Zr results in a constant high catalytic activity (83% hydrogen yield at 800°C) due to the presence of reducible "NiO‐species interacted strongly with the support" (stable metallic Ni over reduced catalyst) and redox input by ceria phase for laying instant lattice oxygen during lag‐off period of CO2. Substitution of Ni by Zr and Y in the CeNiO3 catalyst system nurtures Ni3Y (providing highly stable metallic Ni for CH4 decomposition) and cerium yttrium oxide phases (providing strong redox input). CeNi0.9Zr0.01Y0.09O3 shows 85% H2 yield at 800°C. [ABSTRACT FROM AUTHOR]

Aiming at understanding the role of CH4/CO2 ratio on gliding arc (GA)‐based dry reforming of methane (GA‐DRM), the GA‐DRM at CH4/CO2 ratio range of 0.11 to 1 was studied with kinetics simulation. The radicals of H, OH, and CH3 are identified as the main reactive species to induce the reactant conversion and product formation in GA‐DRM. The increase of CH4/CO2 raises the concentrations of H and CH3 and reduces the OH concentration. Subsequently, the CH4/CO2 ratio regulates the main reaction routes of GA‐DRM. The dehydrogenation coupling reaction enhances with CH4/CO2 and thus raises the selectivities of C2 hydrocarbons. The OH‐induced reactions for OH to H2O weaken with CH4/CO2, thereby increasing the H2 selectivity. [ABSTRACT FROM AUTHOR]

Solar-driven CO2 reforming of CH4 is considered a promising approach for achieving CO2 emission reduction and clean energy utilization simultaneously. However, reactors suffer from uneven temperature distribution and severe carbon deposition, leading to low solar-to-fuel efficiency. This study introduces a novel strategy for highly efficient solar-driven thermochemical CO2-to-fuel conversion based on hierarchical triply periodic minimal surfaces (TPMS) biomimetic foam reactors. The biomimetic hierarchical foam reactor exhibits a remarkably high light-to-fuel efficiency of 39.14 %, with CH4 and CO2 conversion rates reaching 72.6 % and 83.9 %, respectively, along with no obvious attenuation over 50 h. A 73.7 % reduction in temperature non-uniformity and a 96.9 % decrease in the carbon deposition rate are also demonstrated. The underlying mechanism is attributed to unique highly interconnected and smooth hierarchical pores, for which large pores promote the penetration of sunlight while small pores enhance fluid-solid energy transfer. Effects of solar irradiation conditions and foam thermal conductivity are investigated numerically, providing guides for further reactor optimization under different operating scenarios. This work presents a new approach for designing and manufacturing efficient direct solar-driven thermochemical CO2-to-fuel conversion reactors using hierarchical TPMS biomimetic foams.

The world's energy systems are undergoing radical change driven by the commitments to achieve net zero emissions and energy independence. Development of clean hydrogen economy is of paramount importance and hydrogen is expected to play a more important role in the future energy market. An interesting way to produce hydrogen is via dry reforming reaction which uses two green house gasses (CH4 and CO2) as feedstock. Dry reforming is a challenging reaction to scale-up due to its high endothermic and coke formation nature. Microwave has gained interest in the past years as a superior heating mechanism in catalytic reactions due to its capacity in enhancing conversions of reactants and selectivity of products, and suppression of coke formation. Such characteristics has made microwave an excellent alternative to conventional heating in dry reforming reaction. In this study, we aim to discuss different aspects of microwave heating technology and its application in the catalytic dry reforming of methane. The advantages of microwave-assisted methane reforming are discussed via the comparison to the conventional heating.

The effects of operating parameters such as reaction temperature, space velocity, and feed gas composition on the performance of the methane dry-reforming reaction (DRM) over the Ni/Al2O3 catalyst are systemically investigated. The Ni/Al2O3 catalyst, which is synthesized by conventional wet impregnation, showed well-developed mesoporosity with well-dispersed Ni nanoparticles. CH4 and CO2 conversions over the Ni/Al2O3 catalyst are dramatically increased as both the reaction temperature is increased, and space velocity is decreased. The feed gas composition, especially the CO2/CH4 ratio, significantly influences the DRM performance, catalyst deactivation and the reaction behavior of side reactions. When the CO2-rich gas composition (CO2/CH4 > 1) was used, a reverse water gas shift (RWGS) reaction significantly occurred, leading to the consumption of hydrogen produced from DRM. The CH4-rich gas composition (CO2/CH4 < 1) induces severe carbon depositions followed by a reverse Boudouard reaction, resulting in catalytic activity drastically decreasing at the beginning followed by a stable conversion. The catalyst after the DRM reaction with a different feed ratio was analyzed to investigate the amount and structure of carbon deposited on the catalyst. In this study, we suggested that the optimal DRM reaction conditions can achieve stable performances in terms of conversion, hydrogen production and long-term stability. [ABSTRACT FROM AUTHOR]

Biogas is a renewable biomass energy source mainly composed of CH4 and CO2. Dry reforming is a promising technology for the high-value utilization of biogas. Some impurity gases in biogas can not be completely removed after pretreatment, which may affect the performance of dry reforming. In this study, the influence of typical impurities H2S and NH3 on dry reforming was studied using Ni/MgO catalyst. The results showed that low concentration of H2S in biogas could cause serious deactivation of catalyst. Characterization results including EDS, XPS and TOF-SIMS confirmed the adsorption of sulfur on the catalyst surface, which was the cause of catalyst poisoning. We used air calcination method to regenerate the sulfur-poisoned catalysts and found that the regeneration temperature higher than 500 °C could help catalyst recover the original activity. NH3 in the concentration range of 50–10000 ppm showed a slight inhibitory effect on biogas dry reforming. The decline rate of biogas conversion efficiency increased with the increase of NH3 concentration. This was related to the reduction of oxygen activity on catalyst surface caused by NH3. The synergetic effect of H2S and NH3 in biogas was investigated. The results showed that biogas conversion decreased faster under the coexistence of H2S and NH3 than under the effect of H2S alone, so as the surface oxygen activity of catalyst. Air calcination regeneration could also recover the activity of the deactivated catalyst under the synergetic effect of H2S and NH3. [ABSTRACT FROM AUTHOR]

Ruthenium (1 wt%) catalysts supported on alumina doped with alkaline (Na and K) and alkaline earth metals (Ba, Ca, and Mg) of different concentrations (1, 5, and 10 wt%) were tested in the dry reforming of methane. All catalysts were prepared by the successive impregnation method. Supports were characterized by X-ray diffraction, BET surface area, temperature-programmed desorption of CO2, and 2-propanol dehydration. Additionally, catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Stability tests to study coke deposition were performed using long-time dry reforming reactions. All the catalysts showed good catalytic activity, and activity falls were never detected. Ru metallic phase seemed to be resistant to coke formation even though its particles are sintered during a long-term reaction. [ABSTRACT FROM AUTHOR]

Solar-driven photothermochemical dry reforming of methane (PTC-DRM) has attracted increasing attention to address global climate issues yet still faces challenges of poor stability, especially for Ni-based catalysts. Herein, we developed a strategy to improve PTC-DRM activity and stability of Ni-based catalysts by supporting Ni nanoparticles on CeO 2 incorporated ZrO 2. At 700 °C under 30 suns light irradiation, the resulting Ni-CeO 2 /ZrO 2 exhibited elevated and stable PTC-DRM with H 2 and CO production rates of 713 and 693 mmol g−1 h−1 during a continuous 48 h test, respectively, much higher than those of Ce-free Ni/ZrO 2 (542 mmol g−1 h−1 for H 2 and 534 mmol g−1 h−1 for CO in a 24 h test). The comparisons between photothermochemical and thermochemical performance at the same temperatures indicate that introducing a small amount of CeO 2 lowers the activation energies of CH 4 and CO 2 conversions from 68.6 and 62.9 kJ mol−1 in the dark to 54.7 and 57.7 kJ mol−1 under light, respectively. Mechanism investigation was performed through in situ DRIFTS and catalysts characterization before and after the PTC-DRM reaction, revealing that the plasmonic effect from Ni mitigates coke deposition and benefits the DRM activities and stability under light illumination. CeO 2 , serving as a promoter, enhances metal-support interaction, which also plays beneficial effects in continuously generating oxygen vacancies, facilitating the dissociation of carbonate intermediates, and mitigating coke deposition under light irradiation, thus boosting PTC-DRM activity and stability. This study is essential for designing cost-effective Ni-based catalysts and reaction systems for greenhouse gases conversion to produce syngas using sustainable solar energy. [Display omitted] • Ni-CeO 2 /ZrO 2 enables high PTC-DRM activity and stability. • CeO 2 enhances metal-support interaction. • Oxygen vacancies under light boost carbonates dissociation and coke mitigation. • Light irradiation and CeO 2 lower CH 4 and CO 2 activation energies. [ABSTRACT FROM AUTHOR]

It is aimed to develop SBA-15 supported Ni catalysts with Zr incorporation that can reduce carbon formation for synthesis gas production via dry reforming methane. In this study, Zr-containing SBA-15 support materials were synthesized following a one-pot hydrothermal synthesis method in three different synthesis conditions using HCl (A), NaCl (S) and both HCl and NaCl (B). Ni catalysts containing Zr-SBA-15 support materials were prepared by an impregnation method. Zr-SBA-15 prepared under different synthesis conditions supported Ni catalysts were tested in dry reforming of methane at 750℃. All catalysts were characterized by XRD, N2 adsorption-desorption isotherms, ICP-OES, DRIFTS, SEM, TEM and TG techniques before and/or after reaction tests in order to explain the relationship between catalytic activity and catalyst properties. Unlike the other two catalysts (5Ni@10Zr ̶ B and 5Ni@10Zr ̶ S), the formation of hexagonal platelet and short mesochannels was observed in the Zr-SBA-15 supported Ni (5Ni@10Zr ̶ A) catalyst synthesized in the presence of HCl. It was determined that Zr (4.5% by weight) incorporated into the structure of 5Ni@10Zr ̶ A catalyst improved the catalytic activity (85% CH4 and 88% CO2 conversions) and significantly reduced carbon formation. In addition, the highest H2/CO ratio and H2 yield were obtained with 5Ni@10Zr ̶ A catalyst as 0.79 and 1.37, respectively. [ABSTRACT FROM AUTHOR]

Internally circulating fluidized bed reactor (ICFB) is the reactor that combines the conventional circulating fluidized bed (CFB) reactor system, including riser, downer, loop seal and cyclones, into a single compact reactor column. The ICFB reactor column is separated into two sections (riser and downer) by baffles and is linked together via connecting ports. The solid particles are circulated in the ICFB reactor by unequal fluidizing velocities in the riser and downer sections. The solid particles in the downer section are operated with low fluidizing velocity in the bubbling fluidization regime. In the riser section, the solid particles are transferred to the downer section because of the high fluidizing velocity. In this study, the carbon dioxide reforming or dry reforming reaction of methane was investigated. Dry reforming is a reaction between carbon dioxide and methane, which are the major greenhouse gases, for producing syngas, hydrogen and carbon monoxide. The hydrodynamics and dry reforming reaction with different reactor designs were explored using two-dimensional Eulerian–Eulerian computational fluid dynamics simulation (CFD). The ICFB reactor with no elevation gas distributor, 90 cm of draft tube height, 2 cm of loop-seal length and 1 cm of gas outlet diameter gave the highest methane conversion of 15.4%. The analysis of variance (ANOVA) indicated that the length of loop-seal and the gas outlet diameter gave substantial negative and positive effects on methane conversion, respectively. The interaction between length of loop-seal and gas outlet diameter also had a significant effect on the methane conversion. Although the ICFB reactor in this study gave the methane conversion slightly lower than referenced literature conventional CFB reactor, the ICFB reactor is the reactor that can reduce construction cost and simplify complex reactor operation.

This study explores the efficacy of Cr, Mn, and Co promoters in enhancing the performance of 10%Ni/Al 2 O 3 -10%CeO 2 catalysts during methane combined reforming process, emphasizing improved metal dispersion and reduced carbon formation. The supports and catalysts were synthesized through mechanochemical and impregnation methods, respectively, and characterized using XRD, BET, TPR, TPO, and FESEM analyses. The synthesized catalysts exhibited a high BET surface area, ranging from 195 to 172 m2 g-1, along with a mesoporous structure characterized by pore sizes between 2 and 12 nm. The introduction of Cr significantly enhanced catalyst performance, resulting in 70.5 % CH 4 and 69.1 % CO 2 conversions in dry reforming. TPO analysis indicated reduced carbon deposition on promoted catalysts by enhancing Ni dispersion and carbon reactivity. The 10%Ni–3%Cr/Al 2 O 3 -10%CeO 2 catalyst demonstrated stability over 440 min at 700 °C, achieving 84.9 % CH 4 and 68.1 % CO 2 conversions in combined reforming. The TPO analysis indicated an absence of carbon deposition on the catalyst surface during combined reforming, which was corroborated by the FESEM analysis. Furthermore, the influence of operating parameters on catalyst efficiency in both dry and combined reforming processes was investigated. As GHSV increased from 8000 to 24,000 ml/h.gcat, CH 4 conversion declined in dry reforming and combined reforming, dropping from 77 % to 66 % and from 86 % to 84 %, respectively. Also, in both processes, increasing the oxidizer contents (CH 4 : CO 2 from 2:1 to 1:2, CH 4 : CO 2 : O 2 from 1:1:0 to 1:1:0.35) led to an increase in CH 4 conversion, while CO 2 conversion decreased. • Cr, Mn, and Co-promoted Ni/Al 2 O 3 -CeO 2 catalysts were used in combined reforming. • The introduction of Cr to the catalyst enhanced carbon resistance of the catalysts. • Cr (3)-Ni(10)/Al 2 O 3 -CeO 2 (10) possessed the best efficiency among the studied samples. [ABSTRACT FROM AUTHOR]

The impact of two-dimensional Mo 2 C (2D-Mo 2 C) on the activity and stability of a Ni/γ-Al 2 O 3 catalyst for the dry reforming of methane (DRM) is reported. 1.1 wt% 2D-Mo 2 C added to 13 wt% Ni/γ-Al 2 O 3 increased activity by ∼40 %. Characterization results showed an interaction between 2D-Mo 2 C and Ni that resulted in the formation of a Ni x Mo y bulk phase (XRD) and Ni-Mo-oxycarbide surface species (XPS). The presence of 2D-Mo 2 C also improved the stability of the catalyst compared to Ni/γ-Al 2 O 3 by reducing coke deposition. H 2 space-time-yields (STYs) were independent of CO 2 partial pressure and were lower than the CO STYs. Power law kinetic models were consistent with a DRM reaction pathway via CH 4 decomposition (MD) and the reverse Boudouard (RBD) reactions. [Display omitted] • 2D-Mo 2 C added to a Ni/γ-Al 2 O 3 dry reforming catalyst. • The TOF over the 2D-Mo 2 C-Ni/γ-Al 2 O 3 was 2x's greater than Ni/γ-Al 2 O 3 • Catalyst stability also increased significantly compared to Ni/γ-Al 2 O 3 • Power law kinetics suggested that DRM occurred through a combination of MD and RBD. [ABSTRACT FROM AUTHOR]

[Display omitted] • Macroporous Ni/Ce x Zr 1-x O 2 –Al 2 O 3 catalysts are prepared by a one-pot method. • Needle-shaped NiAl 2 O 4 species is formed by favorable interaction between Ni and Al. • NiAl 2 O 4 transforms into highly dispersed Ni and defective Al 2 O 3 in a reduction step. • Abundant oxygen vacancies near Ni0 enhance CO 2 activation and coke gasification. In this study, we report the formation of needle-shaped NiAl 2 O 4 via favorable interactions between Ni and Al species over macroporous Ni/Ce x Zr 1-x O 2 –Al 2 O 3 catalysts for dry reforming of methane (DRM) and its remarkable improvement in the catalytic performance. The macroporous catalysts prepared by a one-pot (OP) method promote a favorable interaction between Ni and Al species that results in the formation of unique needle-shaped NiAl 2 O 4 due to easy access to each other compared with that by incipient wetness impregnation. The NiAl 2 O 4 phase in the calcined catalysts transforms into highly dispersed Ni and defective Al 2 O 3 via the Ni exsolution in the reduction step. The presence of oxygen vacancies near Ni0 species facilitates the CO 2 activation and enhances the catalyst stability over DRM. The optimized distribution of active sites with abundant defects over macroporous Ni/Ce x Zr 1-x O 2 -Al 2 O 3 catalysts (OP) result in high conversions of CH 4 and CO 2 and a low coking rate in DRM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni/SiO 2 catalysts were prepared by wet impregnation and ammonia evaporation methods. • Ni phyllosilicate induced high dispersed Ni due to strong interaction with support. • Ni/SiO 2 @SiO 2 core shell structure was successfully prepared by sol–gel method. • The highly dispersed Ni and confining effect cause excellent coke resistance. Suppressing coke formation on nickel-based catalysts used in methane-dry reforming is one of the most important issues. We investigate the effect of nickel metal-support interaction and outer porous silica shells on the coke formation in methane dry reforming over Ni/SiO 2 @SiO 2 core–shell catalysts. Using a simple ammonia evaporation method, the Ni/SiO 2 _AE catalyst, which has highly dispersed nickel nanoparticles with ca. 7 nm, was synthesized and coated with an outer porous silica shell to produce a Ni/SiO 2 _AE/SiO 2 core shell catalyst. Based on the TEM and N 2 isotherm results, a 20 nm thick SiO 2 shell having pores with a size of about 2 nm was uniformly coated on the Ni/SiO 2 _AE catalyst. H 2 -TPR, and XPS analysis results suggest that the Ni/SiO 2 _AE and Ni/SiO 2 _AE@SiO 2 catalysts have high nickel dispersion. This high dispersion is due to strong metal-support interactions and the formation of Ni phyllosilicate species. On the other hand, the ones synthesized by wet impregnation method have low nickel dispersion due to weaker metal-support interactions. The Ni/SiO 2 _AE@SiO 2 core–shell catalyst showed stable catalytic activity under methane dry reforming conditions at 600 °C. On the other hand, the Ni/SiO 2 _WI and Ni/SiO 2 _AE catalysts showed rapid deactivation due to severe coke formation. It can be concluded that the strong metal-support interaction and the silica shell can suppress catalyst deactivation caused by coke formation very effectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doping demonstrated a positive effect on the conversions of CH 4 and CO 2. • N-doping promotes the formation of carbon protective layer and inhibits the agglomeration of active metals. • N-doping enhances the CO 2 adsorption capacity of catalyst and inhibits carbon deposition. • The N-Ni/C@ZIF-67 catalyzed DRM process mainly occurs through rapid reactions between intermediates. Dry reforming of methane (DRM) can convert CO 2 into syngas for the production of fuels and chemicals, offering both environmental and energetic benefits. However, its large-scale industrial applications face challenges such as harsh reaction conditions and catalyst deactivation. In this study, metal–organic frameworks (MOFs) derived N-doped Ni-based bifunctional nanomaterials (Ni-Co/NC) were meticulously synthesized to function as microwave absorbers and catalysts. Efficient syngas production was achieved through the microwave-enhanced DRM process over Ni-Co/NC. The results showed that the Ni-Co/NC catalyst significantly increased the conversion of CH 4 (∼93.2 %) and CO 2 (∼94.8 %). By comparing the changes in the surface properties of the catalysts before and after N-doping, it was found that N-doping enhanced the interaction between the carrier and metal particles, improved the specific surface area and surface basicity, and inhibited the aggregation of metal particles, thereby enhancing catalytic activity. The reaction mechanism was investigated using in-situ infrared spectroscopy, revealing that the formation of intermediates such as carbonates, formates, O-H groups was crucial to improving catalytic activity and stability. Compared to conventional catalytic processes, the catalysts prepared in this study demonstrated stronger catalytic activity and stability in the microwave catalytic process. [ABSTRACT FROM AUTHOR]

The effect of the CO 2 :C 2 H 6 feed ratio, the relative Lewis acidity of reducible and unreducible catalytically active metal oxide supports with and without Fe 3 Ni 1 alloy nanoparticles on the activity, selectivity and stability for the CO 2 -mediated oxidative dehydrogenation of ethane (CO 2 -ODHE) is investigated. To circumvent the influence of the typically dissimilar textural properties of the supports in bulk form, overlayer oxide supports of V, Cr, Ga, Ti or Sm coated on a common γ-Al 2 O 3 carrier were employed. Separately, (Ni 0.75 Fe 0.25)Fe 2 O 4 precursor nanoparticles were synthesized via a nonaqueous surfactant-free method, sonication-deposited onto supports and reduced in situ into an Fe 3 Ni 1 alloy microstructure of bcc and fcc mixed phases captured with in situ XRD. When exposed to carbon dioxide at 255 °C, a selective re-oxidation of the bcc phase via CO 2 dissociation is observed, while the fcc phase stays stable and only partially re-oxidizes above 525 °C. Upon exposure to CO 2 -ODHE conditions, the initial activity of the bare supports increases with increasing acid site strength, but this activity is rapidly lost in case of the strongly acidic supports. Comparison of the C 2 H 4 and CO selectivity indicate direct dehydrogenation is preferred over the oxidative dehydrogenation pathway and is initially occurring in combination with some CO-forming routes, possibly the dry reforming of C 2 H 6. This CO forming route is significant over the most acidic and reducible VO x @Al 2 O 3 support in the early stages of operation. The addition of the Fe 3 Ni alloy increases the conversions of both C 2 H 6 and CO 2 across all supports, with a notably stronger effect observed on CO 2 conversion especially over the highly acidic and reducible VO x @Al 2 O 3 and CrO x @Al 2 O 3. As a result, the CO selectivity is increased due to ethane dry reforming activity over the latter supports while CO 2 -ODHE activity is observed over the supports with intermediate and weak acid sites. [Display omitted] • The initial activity of bare supports increases with acid site strength but is lost rapidly for strongly acidic supports. • Direct dehydrogenation with dry reforming are dominant initially and increase with the bare support acidity. • Supported catalysts show improved activity with increasing support acidity especially in CO 2 conversion. • Improved activity, especially on strongly acidic supports, results in DRE activity and weakening acidity promotes CO 2 -ODHE. • CO 2 -rich feed improves the catalyst stability and yields owing to promotion of the reverse Boudouard reaction. [ABSTRACT FROM AUTHOR]

Capturing CO 2 and converting it into valuable chemicals and fuels have been regarded as a pivotal strategy in addressing the environmental challenges of ever-growing CO 2 emissions. Combining CO 2 capture and conversion through material or process integration can eliminate the energy-intensive steps such as separation, compression, and transportation across a wide range of space and temperatures. The flue gas at high temperatures > 300 °C can be handled with dual-function materials consisting of sorbents and catalysts. The dual-function materials combine CO 2 capture and conversion through material integration, converting CO 2 with reactions such as methanation, reverse water-gas shift, dry reforming of CH 4 , and oxidative dehydrogenation of propane. On the other hand, capturing CO 2 from air directly requires a long time to collect enough CO 2 for the subsequent conversion reaction. Consequently, direct air capture will likely combine with the conversion reactions in stepwise operations. The low latent heat in CO 2 from direct air capture makes it more suitable for reactions at a mild condition (< 250 °C), and stepwise operation allows the separate control of the capture and conversion conditions. Herein, we reviewed recent advancements in coupling CO 2 capture from flue gas and ambient air with thermal catalytic conversion. We discussed the requirements for materials, reactor configuration, and process operation for capturing and converting CO 2 from these sources and proposed that future research should focus on enhancing the efficiency, scalability, and sustainability of CO 2 capture and conversion technologies and optimizing the process design. [Display omitted] • Summary of progress in thermal catalytic approaches for integrated CO 2 capture and conversion. • Identification of different modes of integration for capturing and converting CO 2 from flue gas and ambient air. • Review of techno-economic assessments for ICCC and DACC. • Proposed future research focus areas. [ABSTRACT FROM AUTHOR]

In the present research a cogeneration cycle based on a solid oxide fuel cell (SOFC), and Organic Rankine Cycle (ORC) is proposed. The cycle is fed with biogas in different molar ratios of carbon dioxide to methane (RCTC). In addition, the cycle is examined for both dry reforming (DR) and steam reforming (SR). A thermochemical model is presented for both cycles of SR–SOFC–ORC, and DR–SOFC–ORC. The model is coded in MATLAB coupled with Engineering Equation Solver software. The model was verified with both experimental and theoretical research and agreement was achieved. The energy and exergy performance of the cycle is presented and carbon deposition on the cathode due to different reactions of methane cracking, Boudouard reaction, and vapor formation are studied. The results show that for RCTC<1.2 steam reforming produces more hydrogen, while for RCTC>1.2 dry reforming is advantageous. At RCTC = 1.2 the DR and SR work the same. The overall thermal efficiency of DR-SOFC and SR-SOFC has reached 67 % and 70 %. Carbon deposition due to the Boudouard reaction, and vapor formation for both SR and DR are negligible while due to methane cracking is serious. The DR-SOFC deposits less carbon because of methane cracking due to higher operating temperatures. • A cogeneration cycle based on a biogas fueled SOFC and ORC is proposed. • The cycle is assessed with both dry and steam reforming. • The impact of different biogas compositions on cycle performance is evaluated. • Carbon deposition on the cathode is investigated. • The cycle based on steam reforming has higher efficiency. [ABSTRACT FROM AUTHOR]

Introduction: Innovating technologies to efficiently reduce carbon dioxide (CO2) emission or covert it into useful products has never been more crucial in light of the urgent need to transition to a net-zero economy by 2050. The design of efficient catalysts that can make the above a viable solution is of essence. Many noble metal catalysts already display high activity, but are usually expensive. Thus, alternative methods for their production are necessary to ensure more efficient use of noble metals.Methods: Exsolution has been shown to be an approach to produce strained nanoparticles, stable against agglomeration while displaying enhanced activity. Here we explore the effect of a low level of substitution of Ni into a Rh based A-site deficienttitanate aiming to investigate the formation of more efficient, low loading noblemetal catalysts.Results: We find that with the addition of Ni in a Rh based titanate exsolution is increased by up to ∼4 times in terms of particle population which in turn results in up to 50% increase in its catalytic activity for CO2 conversion.Discussion: We show that this design principle not only fulfills a major research need in the conversion of CO2 but also provides a step-change advancement in the design and synthesis of tandem catalysts by the formation of distinct catalytically active sites.