Biogas dry reforming over nickel-silica sandwiched core–shell catalysts with various shell thicknesses

Abstract

A series of nickel-silica sandwiched catalysts were synthesized to investigate the effect of shell thicknesses on the reaction of dry reforming. The thicknesses of the silica shell were adjusted by TEOS content and coating time of the silica shell. The outcomes exhibited that encapsulating the Ni-SiO2 catalyst by mesoporous silica shell effectively decreased carbon formation. Higher carbon resistance property of the nickel-silica sandwiched catalyst was related to the confined nickel particles by silica shell, which immobilizes metal particles, hampers the agglomeration and prevents uprooting Ni particles by the growing filamentous carbon. The results revealed that the amount of carbon deposition gradually decreased with the augment of TEOS content. The sandwiched catalyst with 2 ml TEOS exhibited high methane and CO2 conversions of 71.5% and 91.5% under CH4/CO2 = 1.5 and T = 700 °C for 20 h, respectively. Also, negligible carbon was observed on the surface of the catalyst and the original structure of the catalyst was well preserved after the stability test. The results revealed that with an increase in coating time, the catalytic activity improved and carbon deposition decreased.