Effect of ceria and zirconia promoters on Ni/SBA-15 catalysts for coking and sintering resistant steam reforming of propylene glycol in microreactors

Highly dispersed and size controlled Ni nanoparticles in CeO2, ZrO2 and CeO2-ZrO2 promoted mesoporous SBA-15 silica were achieved with the aid of treatment by ultrasound. The catalysts were characterized systematically to investigate their morphological structure and surface properties. It was found that Ni nanoparticles with an average particle size of about 4.5 nm have been successfully embedded in the nanochannels of SBA-15 with a homogeneous distribution. The incorporated CeO2 and ZrO2 promotors effectively controlled the size of the Ni particles via strong Ni-promotor interaction, leading to well dispersed Ni particles in the confined nanochannels of SBA-15. The catalysts thus obtained were applied for steam reforming of propylene glycol in continuous flow microchannel reactors, which reduce the heat and mass transfer limitations when operating them under conditions of highly endothermic reforming reactions. The CeO2, ZrO2 and CeO2-ZrO2 promoted Ni/SBA-15 catalysts exhibited superior activity and enhanced long-term stability compared to the Ni/SBA-15 catalyst without promotor addition. This can be attributed to the strong interaction between Ni and the promotors and the confinement effect of the SBA-15 support restricted the sintering of Ni particles. The surface oxygen species arising from CeO2 and ZrO2 contributed to suppressing the carbon deposition effectively, leading to a consistent catalytic performance during propylene glycol reforming.