Acrylic acid synthesis by oxidative condensation of methanol and acetic acid on B–P–V–W–Ox/SiO2 catalyst

Abstract

The process of oxidative condensation of methanol with acetic acid to acrylic acid on B–P–V–W–Ox/SiO 2 catalyst modified by hydrothermal method has been studied. Modification of the catalyst by hydrothermal treatment of the carrier changes its physical and chemical properties, and therefore its catalytic properties. The influence of the main technological parameters – temperature, contact time and ratio of reagents on the selectivity and yield of the reaction products and on the conversion of acetic acid has been studied when hydrothermally treated catalyst was used. The best time of contact was 8 sec. which allows to reach the highest selectivity and yield of acrylic acid and methyl acrylate. The highest catalytic activity of the designed catalyst is observed at the reaction temperature of 673 K, however, it is impossible to increase temperature over this value due to the limited thermal stability of the catalyst and the sharp increase in the formation of complete oxidation products. With an increase of methanol part in the ratio of reagents (methanol: acetic acid) to 1,2:1, the selectivity of acrylic acid and methyl acrylate increases, and the selectivity of by-products is significantly reduced. The highest yield of the target products in the reaction of oxidative condensation of methanol with acetic acid is observed at a ratio of oxygen: acetic acid 1,5:1. The growth of the oxygen: acetic acid ratio promotes reduce of acetone and methyl acetate selectivity but does not change the selectivity of methyl acrylate and significantly increases the selectivity and yield of acrylic acid. At the best conditions of the reaction it was possible to achieve 54.7 % total yield of acrylic acid and methyl acrylate. Due to the wide availability and relatively low cost of the initial reagents (methanol and acetic acid), the synthesis of acrylic acid by the oxidative condensation of methanol with acetic acid in the presence of the developed catalyst is very promising