Silicon nitride supported copper boosting the selective hydrogenation of dimethyl oxalate to methyl glycolate

The selective hydrogenation of syngas-derived dimethyl oxalate (DMO) to methyl glycolate (MG) is an attracting downstream route for clean coal conversion. Developing efficient non-noble metal catalysts remains a significant challenge due to the tendency for over-hydrogenation. Herein, we prepared a series of atomically dispersed copper catalysts supported on Si 3 N 4 , oxidized silicon nitride (Si 3 N 4 @SiO 2 ), and SiO 2 to explore the chemical environment effect on catalytic performance. The Cu/Si 3 N 4 exhibited 89 % DMO conversion and 86 % MG selectivity, of which MG yield is threefold of that over the Cu/SiO 2 . Combined with various characterizations and density functional theory calculation, it is revealed that electron-deficient copper on the nitrogen-rich surface of Si 3 N 4 promoted hydrogen dissociation and this chemical environment greatly facilitated MG desorption, thus preventing the over-hydrogenation and improving the MG selectivity. This study highlights the pivotal role of chemical environment in optimizing the performance of copper-based catalyst for selective hydrogenation of symmetric-structured esters.