Lanthanum and Cesium-Loaded SBA-15 Catalysts for MMA Synthesis by Aldol Condensation of Methyl Propionate and Formaldehyde

Abstract

Aldol condensation of methyl propionate (MP) and formaldehyde (FA) is a green and sustainable route to synthesize methyl methacrylate (MMA). In this work, lanthanum and cesium-loaded SBA-15 acid–base bifunctional catalysts for aldol condensation have been prepared by wetness impregnation method to maximize the yield of MMA. With the investigation of the relationship between the properties of catalysts and the catalytic performance, the appropriate acid–base sites for this reaction were provided. The results showed that La existed as LaONO3 on the catalysts and could constitute additional Lewis acid sites on the catalysts. The Cs-0.1La/SBA-15 (with La content of 0.1 %) exhibited higher catalytic activity than the other La-containing catalysts because of the higher density of medium base sites and medium acid sites. The catalysts calcined at 450 °C performed well on this reaction due to the formation of medium base sites on the catalysts as well as the big surface area around 400 m2/g and uniform pore size at 6 nm. When the MP/FA molar ratio was 1/1, the conversion of MP was 29.2 % and the selectivity of MMA could reach 90.4 %.