Promotion effect by Mg on the catalytic behavior of MgNi/WO3 in the CO methanation

Abstract

In this study, tungsten oxide with a high specific surface area was fabricated using a nanocasting technique and used to prepare support for nickel catalysts for CO methanation. Additionally, Mg was further introduced as a promoter for tuning the catalytic performance. The 25Ni/WO3 catalyst demonstrated a relatively high CO conversion, but a poor CH4 selectivity; however, with the addition of 7 wt% Mg to the catalyst, the CH4 selectivity reached 92% at a temperature of 440 °C. The improved CH4 selectivity can be attributed to the enhanced CO dissociation, which was related to the reduced Ni particle size, as well as the enhanced Ni electron cloud density. The role of a physical barrier and electron transfer of MgO induces an enhancement of the metal–support interactions, which are conducive to decreasing the Ni particle size. Meanwhile, the electron transfer performance of MgO constitutes a crucial factor in enhancing the Ni electron cloud density. Furthermore, with benefit from the inhibition of agglomeration of the Ni particles by the MgO promoter, a significantly better catalytic stability was also observed on 7Mg25Ni/WO3 than with the 25Ni/WO3 catalyst.