Influence of hydrothermal treatment of catalysts on their effectiveness in the process of acrylic acid and methyl acrylate synthesis via oxidative condensation of methanol with acetic acid

Abstract

The purpose of the work was to investigate the effect of modification of the catalyst of oxidative condensation of methanol with acetic acid on acrylic acid and methyl acrylate selectivity and yield. It was carried out hydrothermal treatment of the support - silica gel, in the temperature range of 100-250 oC in the range of 25 oC. It was investigated the effectiveness of the developed catalyst in the optimal conditions: temperature – 400 oC, reagents ratio CH3OH: CH3COOH = 1.2: 1, oxygen concentration in the oxidant stream is 90 % and contact time – 8 seconds. Physical and chemical properties of the catalysts for the process of acrylic acid and methyl acrylate synthesis by oxidative condensation of methanol with acetic acid were determined. Hydrothermal treatment of the silica gel, KSKG brand was performed and based on this treated silica gel catalytic system SiO2 / B2O3-P2O5-WO3-V2O5 with the atomic ratio of components В:Р:W:V=3:1:0,18:0,12 were prepared. The catalysts were tested in the process of acrylic acid and methyl acrylate synthesis. It has been established that the best catalyst for the process of acrylic acid and methyl acrylate synthesis is the catalyst with a HTT temperature of 150 0С (under optimum conditions the temperature of the process is 400 ºС and contact time 8 s). At this temperature, it was possible to obtain acrylic acid and methyl acrylate with 54.7 % yield, total selectivity of acrylic acid and methyl acrylate – 97.6 %, acetic acid conversion – 56.9 %. It was established that increasing of hydrothermal treatment temperature leads to increasing of pore size of the catalysts and decreasing the acrylic acid selectivity and increasing of esters (methyl acetate and methyl acrylate) selectivity