Effect of ZnO on ethanol conversion to 1,3-butadiene (BD) on ZnO/MgO-SiO2 catalysts consists in the enhancement of selectivity and yield of BD due to higher rate of ethanol dehydrogenation to acetaldehyde. It has been shown that two types of Lewis acid sites formed in the contact zones of MgO-SiO2 and ZnO-SiO2 in the catalysts play an important role in BD synthesis from ethanol. The highest BD yield is achieved at ratio of MgO:SiO2 = 1:1. [GRAPHICS] .