Gas-phase epoxidation of butadiene: influence of the content and distribution of cesium promoter on catalytic properties Ag/α-Al O
The aim of this work is the selection of optimum conditions for promotion of silver catalysts by cesium nitrate. Using known patents methods, catalysts epoxidation of 1,3-butadiene were synthesized 15 wt.% Ag and 250-1500 ppm Cs on α-Al2O3 (Johnson Matthey, H16P07). Varying the silver dispersion, the amount of injected promoter and its distribution on the catalyst surface, a systematic study of the physicochemical properties of the samples was carried out. Catalytic testing of the samples showed that the optimal amount of promoter is directly dependent on the catalyst surface. In the optimal condition of promotion the catalyst activity is determined from the dispersion of deposited silver. The shape of kinetic curves is depended on Cs excess or deficiency in the catalyst, this can be used as a method of determining the promoter optimal content. The energy dispersive spectroscopy was first applied to study the Cs distribution on the surface of the promoted catalysts. It is shown that heat treatment contributes the even distribution of the promoter on the catalyst surface and reduces the time required to reach steady-state activity in the catalytic process. We achieved steady-state performance of catalysts 0,5 g of 3,4-epoxy1-butene to 1 g of catalyst per hour, what exceeding the claimed value of the patents.