Cesium Loaded on an Al-Modified Silica Support Catalyst for Methyl Acrylate Synthesis by Aldol Condensation of Methyl Acetate and Formaldehyde

An Al-modified silica-supported cesium catalyst was prepared by an incipient wetness impregnation method for the gas-phase aldol condensation reaction of methyl acetate and formaldehyde. The effect of the Al-modified silica support on the structure, specific surface area, and the acid property was studied using X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption, NH3-temperature programmed desorption, X-ray photoelectron spectroscopy, and Py-IR. Adding the cesium species, the Cs–Al/SiO2 catalyst performed well based on the evaluation results in a fixed-bed reactor. A combination of these characterization and testing results manifests the influence of acid–base properties on the catalytic activity. It was found that the selectivity was related to the amount of weak acid sites and medium-strong base sites. The highest selectivity of methyl acrylate (MA) was obtained at T = 355 °C, LHSV = 0.6 h–1, and Ma/FA/MeOH molar ratio = 1:1:2 over the 10% Cs–3% Al/SiO2 catalyst. Finally, the performance of the optimized catalyst did not exhibit an obvious decrease via three times in situ regeneration.