Due to the low efficiency of known catalysts of aldol condensation of acetic acid with formaldehyde, studies aimed at creating new or improving existing catalysts of this process are relevant. Creation of active and selective condensation catalysts will facilitate the industrial introduction of acrylic acid production by means of aldol condensation.
It is known that acid-type catalysts provide a satisfactory conversion of the reagents, but their use is accompanied by the formation of a significant amount of by-products. For solving this problem, processes were studied using supports of different nature.
In this paper, the catalytic systems of the composition B-P-W-V-Ox are deposited on a support of different nature in the process of acrylic acid production by aldol condensation of acetic acid with formaldehyde in the gas phase. For research purposes mesoporous supports were used: SiO2, SiO2 HTT 150 °C 3 h, Al2O3 MchT H2O 300 rpm, TiO2 anatase with TiO(OH)2 MchT H2O 300 rpm and Sn(OH)4 - TiO2 MchT 600 rpm. The atomic ratio of components in catalyst B:P:V:W is 3:1:0.18:0.12. The catalytic activity of the developed catalysts was investigated in a flow reactor with a stationary bed of a constant mass catalyst, located on a fixed grid. The composition of the reaction products was determined by the chromatographic method.
The influence of temperature on the activity and selectivity of the catalysts in the process of aldol condensation of acetic acid with formaldehyde to acrylic acid was studied. It has been established that the most efficient in the process of acrylic acid production is the catalytic system B-P-V-W-Ox/TiO2 anatase from TiO(OH)2 MchT H2O 300 rpm. The optimum conditions for this process are 375 °С. In these conditions on the optimum B–P–V–W–Oх/TiO2 anatase catalyst the conversion of acetic acid is 63.8 %, the selectivity of acrylic acid is 92 % and the yield of acrylic acid is 58.8 %.
It is shown that a significant difference in the catalytic properties of B-P-V-W-Ox catalysts deposited on different supports allows us to conclude that the nature of the support has a significant influence on the catalytic properties of the catalysts of acrylic acid production by the aldol condensation of acetic acid with formaldehyde.
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