Promoted nickel-based catalysts on modified mesoporous silica support: The role of yttria and magnesia on CO2 methanation

Abstract

In this research, a group of xY 2 O 3 -Ni/MgO-MCM-41catalysts were synthesized by using direct synthesis method for CO 2 hydrogenation and were characterized by employing BET, XRD, HRTEM, XPS, TPD, FE-SEM and TPO to understand the mechanism of CO 2 hydrogenation over yttria-Ni/MgO-MCM-41. Compared to Ni/MgO-MCM-41, all catalysts which contained Yttria showed improved catalytic activity. The one with 2 wt% yttria had the highest catalytic performance, with carbon dioxide conversion and methane selectivity of 65.55% and 84.44% at 673 K, respectively, and high stability after 30 h. The impact of adding yttria, as a promoter, on nickel dispersion and that of enhancing carbon dioxide adsorption sites on basicity sites attracted more attention as effective factors regarding conversion, selectivity, and stability. Mechanism of effect of adding Yttria on Ni/MgO-MCM-41 in CO 2 methanation process. • Incorporation of Magnesia and Yttria promoters are beneficial for CO 2 hydrogenation. • 2Y 2 O 3 -Ni/MgO-MCM-41 showed the highest CO 2 conversion and CH 4 selectivity. • Adding Yttria increased nickel dispersion, reducibility and oxygen vacancy. • With the increase in the Ni active sites, the dissociation of H 2 to atomic hydrogen increased.