Synthesis of acrylates from methyl propionate, propionic acid and formaldehyde in the gas phase on solid catalysts

Abstract

Development of active and selective catalysts for the process of obtaining methacrylic acid and methyl methacrylate from methyl propionate, propionic acid and formaldehyde is one of important stages to industrial implementation of this process. In order to solve this problem, we designed catalysts based on oxides of boron and phosphorus that were promoted by oxides of zirconium, tungsten and bismuth with varied content of oxides. The effect of temperature was examined on the conversion of reagents, the selectivity of formation and the yield of methyl methacrylate and methacrylic acid on the created catalysts. With increasing temperature, the conversion increases, the selectivity of formation of acrylates decreases and the total yield of acrylates has the maximum. It was found that without adding methanol, the optimal catalyst by acrylates yield is the one, in which the molar ratio of the ZrO 2 :WO 3 promoters is 0.15:0.15. The total yield of the target products at optimum temperature of 593 K is 52.3 % with the total selectivity of their formation at 96.4 % and the conversion of reagents of 54.2 %. We determined the effect of adding methanol to the reagent mixture. Adding methanol increases the ratio of products MMA/MAA, and the optimal catalyst by the total selectivity of formation of the target products is the one promoted by bismuth oxide with the molar ratio of Bi 2 O 3 /Р 2 О 5 – 0.3, which at a temperature of 593 K provides for the selectivity of formation of acrylates of 100 % with the yield of 33 %. The maximum total single­pass yield of MMA and MAA on this catalyst at a temperature of 623 K is 51.5 %, at the total selectivity of their formation of 91.6 %. However, the share of MMA in products is lower in comparison to the catalyst, promoted by the mixture of tungsten and zirconium oxides.