Highly dispersed mesoporous Au/SiO2 catalysts obtained by a direct aerosol-assisted sol-gel process

Supported gold nanoparticles play a fundamental role in modern heterogeneous catalysis. However, controlling their fine dispersion remains a challenge, in particular when using silica supports. Here, we report a simple one-pot aerosol route to Au-SiO2 catalysts featuring small gold nanoparticles and calibrated mesoporous texture. To achieve such result, we rely on the strong interactions between gold and the thiol function of a mercapto-silane. We show that the addition of this gold-stabilizer during synthesis enhances the stability of the gold precursor and is the key to control the formation of small gold nanoparticles in the one-pot synthesis. After calcination, the catalyst displays advantageous textural properties (SSA = 440 m².g-1; Vp = 0.5 cm³.g-1; Dp = 5 nm) with small gold nanoparticles (3.7 nm, compared to 13.7 nm without the stabilizer). The dispersion of gold in the material reaches 21 % (compared to 3 % without the stabilizer). The selective oxidation of glycerol to dihydroxyacetone was employed as a test reaction, of importance in the context of sustainable chemistry. We show that the highly dispersed catalyst obtained via gold stabilization outcompetes benchmark catalysts, reaching a glycerol conversion of 59 % after 8 hours (vs. 5 % without stabilization).