HZSM-35 zeolite catalyzed aldol condensation reaction to prepare acrylic acid and its ester: Effect of its acidic property

Abstract

Acrylic acid (AA) and its ester, methyl acrylate (MA), were produced by a green one-step aldol condensation reaction of dimethoxymethane and methyl acetate. The reaction was conducted over ZSM-35 zeolites with different concentrations of Brönsted acid, which were prepared by the sodium ion-exchange process with H-form zeolite. The acidic property of HZSM-35 was studied in detail through infrared experiments. About 51% of all bridging OH groups were distributed in cages, while 23% and 26%, respectively, were distributed in 10- and 8-ring channels. The catalytic performance was enhanced by a high concentration of Brönsted acid, indicating that Brönsted acid is an active site for the aldol condensation reaction. The ZSM-35 zeolite possessing a concentration of Brönsted acid as high as 0.049 mmol/g demonstrated excellent performance with a MA+AA selectivity of up to 73%.