Towards Efficient Acidic Catalysts via Optimization of SO3H-Organosilane Immobilization on SBA-15 under Increased Pressure: Potential Applications in Gas and Liquid Phase Reactions.

In this paper, the optimization of the synthesis of catalysts based on acidic mesoporous silica of the SBA-15 type by post-synthesis immobilization of 3-(trihydroxysilyl)-1-propanesulfonic acid (TPS) under increased pressure up to 20 bar is reported. Sample structures and composition were examined by XRD measurement, low-temperature N2 adsorption/desorption and elemental analysis. The catalytic activities of the materials obtained were determined in both gas and liquid phase processes, i.e., by esterification of acetic acid and glycerol dehydration, respectively. The optimum pressure for modification leading to the highest number of acidic sites was found to be 10 bar. The final material was very active and stable in liquid phase processes; however, the stability in the gas-phase process was unsatisfactory due to the loss of sulphonic species from the catalyst surface.