Template-Free Synthesis of Macroporous SiO2 Catalyst Supports for Diesel Soot Combustion

Catalytic combustion is considered as one of the most efficient methods for soot removal. However, the limited contact area between soot and active site is a key restrictive factor for the present reaction, as soot particles (particle size > 25 nm) are usually difficult to enter the inner pores of general catalysts. In this work, we report a simple and economic strategy to synthesize macroporous SiO2 as the support for combustion catalysts so as to facilitate the mass transfer in the inner surface of the catalysts. The macroporous SiO2 could be synthesized rationally through controlling and adjusting the Si–OH dehydration condensation and neck growth during the sol–gel preparation process. The porosity of SiO2 influences catalytic activity greatly in the reaction of soot catalytic combustion. Furthermore, macroporous SiO2 supported Ag and K catalysts exhibit superior soot oxidation activity, showing important potentiality for future applications.