Influence of pore structure on catalytic performance of Cs-Zr/SiO2 catalyst for methyl methacrylate synthesis from methyl propionate and formaldehyde

Abstract

Methyl methacrylate (MMA) synthesis via aldol condensation of methyl propionate with formaldehyde over Cs-based supported catalysts is intensively investigated, while the effect of their pore structures on catalytic performance still lacks in-depth understanding. Herein, series of Cs-Zr/SiO2 catalysts with different pore structures were prepared for this aldol condensation. The physicochemical characteristics of as-prepared Cs-Zr/SiO2 catalysts were characterized using physical N2 adsorption–desorption isotherms and CO2–/NH3-TPD. In addition, the impact of pore structure on mass transfer, adsorption, and desorption of reactants and products was studied through in situ DRIFTS. The results show that the acid and base site densities elevated with the increasing pore volume. The mass transfer of reactants and products could be promoted with increasing pore size, while their adsorption energies exhibited a volcanic trend. As a result, the Cs-Zr/SiO2 catalysts having average pore diameter of 12–18 nm and acid-base balance was considered as the optimal candidate for MMA production.