Dry reforming of methane over Mn-Ni/attapulgite: Effect of Mn content on the active site distribution and catalytic performance

Abstract

Designing and manufacturing an eco-friendly and high-efficiency catalyst is the key bottleneck for obtaining synthesis gas from dry reforming of methane (DRM), which is considered as the promising technology for converting the two greenhouse gases (CH4 and CO2). Herein, the modified Ni/attapulgite catalysts with various Mn contents (noted as NxM/A catalysts, x = 0, 1, 3, 5) were prepared by utilizing the sol-gel assisted impregnation method and applied in DRM. A series of characterizations showed that Mn content could alter the distribution among metal sites, interface sites and oxygen vacancies. Amongst, the N3M/A catalyst exhibited the well-dispersed metallic Ni and MnOx species to form abundant Ni-MnOx interfaces that significantly enhances the CH4 adsorption/activation and inhibits simultaneously the sintering and oxidation of metallic Ni sites. Additionally, it also had superior surface oxygen vacancies and medium CO2 adsorption sites (manganese-oxygen ion pairs), facilitating the adsorption/activation of CO2 and carbon removal ability. Therefore, N3M/A catalyst exhibited the optimized performance and could keep the conversions of CH4 and CO2 close to 40% and 60% respectively, and H2/CO molar ratio close to 0.8 after 24 h on stream.