An analysis of the chemical, physical and reactivity features of MgO–SiO2 catalysts for butadiene synthesis with the Lebedev process†
New insights into the transformation of ethanol to butadiene over MgO–SiO2 catalysts, prepared by means of the sol–gel technique, have been gained via characterization, catalytic tests, and in situ infrared diffuse reflectance spectroscopy. Catalysts with low Si-content, i.e., with a Mg/Si atomic ratio in the range between 9 and 15, gave superior butadiene yields, because of the proper combination of strong basic sites, required for ethanol activation, and a moderate number of medium-strength acid sites, needed for the dehydration of intermediately formed alkenols to butadiene. A model of the medium-strength, Lewis-type acid sites, consisting of Mg2+ cations with neighbouring Si4+ atoms, has been proposed; these sites are converted into Brønsted sites in the presence of water, a co-product of the multistep transformation of ethanol into C4 molecules.
- This article is part of the themed collection: 3rd International Symposium on Green Chemistry