Larina O. Effect of the composition of oxide MxOy-SiO2 (M = Mg, Zn, Zr, La) and zeolite Ta/SiBEA catalysts on their catalytic properties in the processes of ethanol conversion into 1,3-butadiene

The thesis is devoted to studying the impact of the composition of oxide MxOy-SiO2 (M = Mg, Zn, Zr, La) and zeolite Ta/SiBEA catalysts on functional properties of surface, regulating these properties to achieve high activity and selectivity in the process of 1,3-butadiene production from ethanol with the further development of high-performance catalysts. Lewis acidic sites active in the 1,3-butadiene production from ethanol are formed as a result of interaction of magnesium and silicon oxide phase. Mechanochemical treatment of MgO-SiO2 composition leads to formation of Lewis acidic sites of medium acidic strength responsible for the ethanol-to-butadiene conversion and reduction of the concentration of strong acidic sites which stimulates ethanol dehydration to by-products. The role of zinc oxide in the catalyst MxOy-SiO2 (M = Mg, Zn) is to forming ethanol dehydrogenation sites and subsequent conversion of acetaldehyde into butadiene. Doping of the catalysts by zirconia dioxide improves butadiene selectivity by forming Lewis acidic sites and increase in the rate of aldol condensation of acetaldehyde. The introduction of lanthanum in the ZnO/ZrO2-SiO2 composition increases its activity and selectivity in 1,3-butadiene production from ethanol due to the formation of basic sites on the surfuce. Highly active and selective ZnO/LaхOy/ZrO2-SiO2 catalysts have been developed. High selectivity of 1,3-butadiene is achieved in the conversion of ethanol/acetaldehyde mixture over Ta/SiBEA zeolite catalysts prepared by heteroelement (Ta) incorporation into dealuminated BEA zeolite matrix. Doping of Ta/SiBEA zeolite catalyst by d-metals (Ag, Cu, Zn) provides formation of surface active sites of ethanol dehydrogenation to acetaldehyde, which allows producing 1,3-butadiene directly from ethanol with high yield.