MoOx‐Doped Ordered Mesoporous Ni/Al2O3 Catalyst for CO Methanation

Abstract

To address the problems of sintering of Ni particles and poor low‐temperature activity of Ni‐based catalysts for CO methanation, MoOx‐doped (x < 3) ordered mesoporous Ni/Al2O3 catalysts are prepared by two different methods, including the impregnation method and evaporation‐induced self‐assembly (EISA) method. The samples before and after the catalytic reaction are thoroughly characterized by scanning electron microscopy and transmission electron microscopy. The ordered mesoporous structure is retained in all catalysts, whereas the ones prepared by the EISA method demonstrate high specific surface area, small Ni particle size, and high metal dispersion. After reduction in H2 flow, the Mo promoter is in the form of MoOx (x < 3) with the mixed valence of Mo (IV) and Mo (VI), which can increase the density of Ni atomic electron clouds and reduce the Ni particle size. The optimal mesoporous Ni‐Mo/Al2O3 catalyst reaches the maximum CO conversion and CH4 yield of 97.9% and 93.8%, respectively, at 375 °C, 0.1 MPa, and a weight hourly space velocity of 60 000 mL g−1 h−1. In addition, this catalyst demonstrates excellent stability in 100 h‐lifetime test at high space velocity owing to the confinement of the ordered mesoporous structure and the addition of MoOx promoter.