Dry reforming of methane over Ni/SiO2 catalysts: Role of support structure properties

Dry reforming of methane (DRM) can take advantage of greenhouse gases (CH4 and CO2) to reduce their impact on the ecological environment. However, the biggest hurdle for the DRM reaction is design of catalysts with strong sintering and carbon deposition resistance. Furthermore, understanding the role of supports is vital for the logical construction of dry reforming catalysts. Here, the effect of support pore structure on DRM catalyst is elucidated by impregnating nickel with inverted conical mesoporous silica spheres (MSS), ordered mesoporous silica (MCM-41), and commercial silica (SiO2). A series of characterizations showed that the MSS with invertedtapered pore structure was favorable for the active components to disperse in the confinement channel, thereby improving the dispersibility of the active metals. In addition, the inverted-tapered pores were more favorable for the contact between reactant molecules and active sites. Compared with 10Ni/MCM-41 and 10Ni/SiO2, the catalyst 10Ni/MSS exhibited the best initial CH4 conversion (85.1 %) and CO2 conversion (90.5 %). The stability test showed that the MSS carrier effectively prevented Ni nanoparticle sintering and carbon deposition. Kinetic studies showed that the unique inverted conical pore structure significantly reduced the apparent activation energies for CH4 and CO2 splitting. These findings provide a new perspective for designing Ni-based dry reforming catalysts.