Combined steam and CO2 reforming of methane over Ni-based catalysts with spherical porous structure

Abstract

Combined steam and dry reforming of methane (CSDRM) is expected to be promising when considered as a new alternative feedstock for F-T synthesis because it can produce high-quality syngas without carbon deposition. In this study, the support particle sizes were varied independently to assess their influence on the performance of the metallic Ni. The catalytic activity is most influenced by nickel particle size and distribution, and it has also been investigated for its significant role in the metal-support interaction. To perform CSDRM, the Ni-based catalyst was prepared by impregnation method on a spherical nano-silica support prepared by sol–gel method. The size of the spherical silica nanoparticles (40–300 nm) was controlled by varying the ethanol molar concentration; the spherical particles showed high performance on a uniform and evenly drawn support. In the 44 nm spherical silica catalyst, it was confirmed that the maximum dispersion increased to 21 % and the reducibility increased to 36 %. For stable synthesis gas production, various feed gas ratios (0.7:1.3:1.7) were established and the respective feed gas components (CH4, CO2 and steam) and reactions were investigated. Also, with the increase in the concentration of steam in the feed gas ratio, there was a significant increase in CO production. This trend was attributed to competing reactions occurring due to the side reactions (WGS↔RWGS; CO+H2O↔CO2 + H2) and was investigated with equilibrium constant values using thermodynamic equilibrium plot data. From the experimental results obtained, the catalyst showed high performance on a stable support and produced a stable H2/CO ratio of 2 for 100 h, without side reactions, at the feed gas ratio (CH4:CO2:H2O = 1:0.6:0.85).