Low-impact synthesis of mesostructured acidic catalysts: toward the efficient conversion of crude glycerol

A series of acidic porous nanospheres with highly controllable particle size were prepared through a rapid (30 min), straightforward (one pot) and sustainable (room temperature) synthetic procedure. The particle size was reduced down to 25 nm and various Si/Ga ratios (in the range of 35 to 137) were investigated. The materials were tested as catalysts for the conversion of glycerol to solketal. The most favorable Si/Ga ratio corresponds to 74 and this solid was reusable over multiple cycles. Importantly, the best catalyst displayed a particularly low E-factor and outstanding catalytic activity compared to previously reported materials including other gallosilicates. The solid was still highly active in the presence of reaction mixtures simulating the crude glycerol composition. The impact of water on the catalytic activity was further mitigated through the functionalization of the catalyst surface with 5 mol% fluorine moieties, leading to a significant increase in the yield of solketal.