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In order to produce valuable syngas, industrial processes of dry reforming of methane and steam reforming of methane must be further developed. This paper is focused on reviewing recently examined catalysts, supporting the mentioned technologies. In both processes the most popular active material choice is usually nickel, due to its good availability. On the other hand, noble metals, such as ruthenium, rhodium or platinum, provide better performance, however the solution is not cost-effective. Materials used as a support influence the catalytic activity. Oxides with basic properties, such as MgO, Al2O3, CeO2, are frequently used as carriers. One of the most promising materials for reforming of methane technologies are hydrotalcites, due to adjustable composition, acid-base properties and possibility of incorporation of various metals and complexes.

In the presented work, the catalytic performance of a nickel catalyst, in CO2 hydrogenation to methane, within a ZrO2 open-cell foam (OCF)-based catalyst was studied. Two series of analogous samples were prepared and coated with 100–150 mg of a Mg-Al oxide interface to stabilize the formation of well-dispersed Ni crystallites, with 10–15 wt% of nickel as an active phase, based on 30 ppi foam or 45 ppi foam. The main factor influencing catalytic performance was the geometric parameters of the applied foams. The series of catalysts based on 30 ppi OCF showed CO2 conversion in the range of 30–50% at 300 °C, while those based on 45 ppi OCF resulted in a significantly enhancement of the catalytic activity: 90–92% CO2 conversion under the same experimental conditions. Calculations of the internal and external mass transfer limitations were performed. The observed difference in the catalytic activity was primarily related to the radial transport inside the pores, confirmed with the explicitly higher conversions. [ABSTRACT FROM AUTHOR]

A series of clinoptilolite-supported catalysts, modified with hydrotalcite-like phase (HT) by co-precipitation, were prepared and tested in NH3-SCR reactions. It was found that deposition of HT on clinoptilolite increased conversion of NO within 250–450 °C, and that the positive impact on the catalytic activity was independent of HT loading. The promoting effect of clinoptilolite was attributed to Brönsted acid sites present in the zeolite, which facilitated adsorption and accumulation of ammonia during the catalytic process. Concentration of N2O in the post-reaction gas mixture reached its maximum at 300 °C and the by-product was most likely formed as a consequence of NH4NO3 decomposition or side reaction of NH3 oxidation in the high-temperature region. The gradual elimination of nitrous oxide, noticed as the material with the highest concentration of hydrotalcite phase, was attributed to the abundance of oligomeric iron species and the superior textural parameters of the material. UV-Vis experiments performed on the calcined samples indicated that Fe sites of higher nuclearity were generated by thermal decomposition of the hydrotalcite phase during the catalytic reaction. Therefore, calcination of the materials prior to the catalytic tests was not required to obtain satisfactory overall catalytic performance in NO reductions. [ABSTRACT FROM AUTHOR]

Co-precipitated Ni-Mg-Al hydrotalcite-derived catalyst promoted with vanadium were synthesized with different V loadings (0–4 wt%) and studied in CO2 methanation. The promotion with V significantly changes textural properties (specific surface area and mesoporosity) and improves the dispersion of nickel. Moreover, the vanadium promotion strongly influences the surface basicity by increasing the total number of basic sites. An optimal loading of 2 wt% leads to the highest activity in CO2 methanation, which is directly correlated with specific surface area, as well as the basic properties of the studied catalysts. [ABSTRACT FROM AUTHOR]

Aiming at a comprehensive understanding of support effects on Ni-based bimetallic catalyst for CO 2 hydrogenation, spectroscopy (DRIFTS) with CO as a probe molecule and temperature-programmed techniques were used to investigate the impact of different supports (MgO, CeO 2 , ZrO 2 ) on Ni- and Ni,Fe catalysts. Kinetic parameters revealed that the higher selectivity to methanation for Ni and Ni,Fe supported on the reducible oxides (CeO 2 , ZrO 2 ) is due to the inhibition of reverse water-gas shift reaction (RWGS) by hydrogen. A promoting effect of Fe on Ni was only observed on MgO-supported catalysts. In situ DRIFTS with CO adsorption showed different electronic properties of Ni sites with partially reduced oxide ( i.e. ZrO 2 and CeO 2 ). H 2 -TPR and CO 2 -TPD confirmed the significant role of metal-support interaction (MSI) in CeO 2 -supported catalysts for CO 2 activation. The MSI between Ni/Ni,Fe and reducible supports are crucial for catalytic performance, ultimately leading to the higher activity and stability in CO 2 hydrogenation.

Making Europe less dependent on imported fuels requires a long-term strategy. Low-quality natural gas and biogas could be used to mitigate the energy crisis, and excess-methane dry reforming has the potential to upgrade a mixture of CH 4 and CO 2 . Herein, nickel-based KIT-6-supported catalysts (KIT-6-Ni) were modified with 3, 6, and 8 wt % of yttrium (Y/Ni molar ratio of 0.5, 1.07, and 1.5) to investigate the influence of this element on catalytic performance. Yttrium was well dispersed, preserving the mesopore structure of KIT-6. The yttrium addition increased the total basicity, contributing to a lower deactivation factor and remarkably stable syngas production compared to the catalyst containing only Ni. In situ XAS-XRD showed that Y allowed for the reduction of Ni 2+ to Ni 0 at significantly lower temperatures. A significant difference in the rate of reduction was observed for the studied samples. The analysis showed that the data of linear combination fitting of XANES can demonstrate linear fits with the reduction rate of NiO. The reduction rate of bulk and weakly interacting NiO increased for Y-promoted samples, while a decrease in the rate was registered for species strongly interacting with the support. The latter decreased more with increasing yttrium content. EXAFS analysis showed that Ni is completely reduced in the samples. Under excess-methane dry reforming conditions, the studied catalysts remained fully reduced and showed resistance to sintering of Ni particles. HRTEM results of KIT-6-Ni5-Y8 indicated that metallic Ni particles were decorated by Y 2 O 3 and/or NiYO 3 . The dominant deactivation mechanism was the carbon encapsulation of Ni particles and the growth of filaments., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)