Silica-Encapsulated Gold Nanoclusters for Efficient Acetylene Hydrogenation to Ethylene

Selective conversion of acetylene impurities to ethylene is a major step in processing chemical feedstock in industry. Currently, this step is widely performed through the catalytic hydrogenation of acetylene over palladium-based materials. Because of a lack of selectivity, however, this method suffers from the formation of ethane to a considerable extent. Herein, we present gold nanoclusters encapsulated in microporous silica as robust catalysts for the hydrogenation of acetylene with 98% selectivity toward ethylene formation. These encapsulated catalysts are designed to avoid the aggregation of nanoclusters during thermal pretreatment at ∼500 °C by maintaining an average nanocluster size of around 1.6 nm. This approach yields an acetylene conversion efficiency of ∼95% at 280 °C. The catalysts are characterized by UV–vis, Fourier transform infrared, NMR, and X-ray spectroscopies as well as density functional theory. Analysis shows that preservation of the nanoscale size of the gold particles at operating temperature coupled with the maintenance of positive charges on the surface active sites induced by the presence of electronegative species of microporous silica can be utilized as an efficient strategy to significantly improve acetylene activation for the semihydrogenation reaction.