Silica of varied pore sizes as supports of copper catalysts for hydrogenation of furfural and phenolics: Impacts of steric hindrance

Abstract

The silica-based materials with varied pore distribution were prepared by adjusting the pH during the self-assembly process and were used as the supporting materials of Cu-based catalysts for hydrogenation of furfural and phenolics. It was found that the pH during the self-assembly process drastically impacted the porous structures of the resulting silica materials. At a lower pH environment (pH = 1.0), the accelerated hydrolysis rate of Na2SiO3 led to the randomly arranged Si species, forming the disordered structures with the pore size of ca. 7 nm. At the higher pH environment (pH = 2.0), the slow hydrolysis rate created the difficulty for grow of silicon precursor on the template, and the disordered mesoporous structures of silica with the pore size of ca. 12 nm were formed. The moderate hydrolysis rate at pH of 1.5 favoured the formation of the ordered pores with the pore size of ca. 3 nm. The results indicated the pores of different sizes induced the distinct steric hindrance, which further affected the efficiency for hydrogenation of the organics with ring structures.