“…Compared to the previously studied catalysts for the process of condensation of MP and FA, promoted by individual tungsten oxide and zirconium oxide, the developed catalysts provide for a much higher selectivity of formation of the target products -methyl methacrylate and methacrylic acid. For example, in the presence of the B 2 O 3 -P 2 O 5 -WO 3 /SiO 2 catalyst, the maximum selectivity of formation of acrylates reached 49.1 % and was achieved at a temperature of 653 K [12], while in the presence of the B 2 O 3 -P 2 O 5 -ZrO 2 /SiO 2 catalyst, the selectivity is 65.4 % at a temperature of 623 K [13]. Thus, the designed B 2 O 3 -P 2 O 5 /SiO 2 catalytic system promoted by ZrO 2 :WO 3 =0.15:0.15 allowed us to increase the selectivity of formation of the target products to 96.4 %, which is 31 % higher, and made it possible to carry out the process of condensation of MP and PA with FA at a lower optimum temperature of 593 K than in the process without propionic acid, confirming possibility and feasibility of the PA recycling in the process of condensation of MP and FA.…”