Origin of active sites on silica–magnesia catalysts and control of reactive environment in the one-step ethanol-to-butadiene process

Wet-kneaded silica–magnesia is a benchmark catalyst for the one-step ethanol-to-butadiene Lebedev process. Magnesium silicates, formed during wet kneading, have been proposed as active sites butadiene formation, and their properties are mainly explained in terms of ratio acid base sites. However, mechanism formation reactivity not yet fully established. Here we show that magnesium silicates by dissolution Si Mg subunits from precursors, initiated alkaline pH wet-kneading medium, followed cross-deposition on precursor surfaces. Using two individual model systems (Mg/SiO2 Si/MgO), demonstrate location (that is, SiO2 or MgO) governs only chemical nature, but also configuration adsorbed ethanol resulting selectivity. By using an NMR approach together with probe molecules, basic close atomic proximity (~5 Å) promote formation. The process established to convert into catalysed prepared so-called method. role impact this uncovered. authors reveal important aspects elucidate different it generates within silica–magnesia.