Effect of niobium addition over Ni/MCM-41 catalysts for dry reforming of biogas.

This work aimed to evaluate the effect of niobium addition on nickel-based catalysts and their performance in dry reforming reactions to produce syngas (H and CO). Different quantities of NbO (5, 10, and 20% w/w) were used to prepare the catalysts, while a fixed content of Ni was applied (20%). The catalysts were supported on MCM-41. Physical, chemical, and morphological analyses were conducted to assess the characteristics of the materials. The produced Nb-Ni catalysts were applied in dry reforming reactions at 800 °C for 12 h. The dry reforming results indicated that the catalyst with 10% Nb-Ni demonstrated the best conversion of CH and CO (> 97%) and a significant H production (40%), with good stability during 12 h of reaction, while the catalyst with 5% Nb-Ni showed lower conversions and did not present good stability during the reaction. The catalyst with 5% Nb-Ni exhibited the highest production of H (44%), and the lowest of CO (50.87%), probably due to the presence of parallel reactions that increased H content and caused carbon (coke) formation. The characterization results of this material revealed the greatest formation of carbon on its surface. The presence of coke can prejudice the efficiency of the catalyst during a reaction and significantly reduce its lifetime. The catalyst with 10% Nb-Ni did not present coke formation, while the catalyst with 20% Nb-Ni showed carbon presence. The good dispersion of Ni on supports (NbO and SiO/MCM-41) can explain the best behavior of 10% Nb-Ni for dry reforming reactions. X-ray diffractometry of the solids suggests the contribution of both metals (Ni and Nb) to the reforming process. From the obtained results, the catalyst with 10% Nb-Ni was indicated as the most favorable for dry reforming reactions among the studied materials, displaying good stability and conversion along with resistance to carbon formation.