Amino functionalization of the support toward enhanced selective hydrogenation of dimethyl oxalate to methyl glycolate on silver–silicon catalysts†

The development of highly efficient catalysts for the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) is an important step in the conversion of syngas into high-value chemicals, which is of great significance for reducing dependence on petroleum and facilitating the transformation of energy structures. Herein three Ag nanoparticles with different size distributions were supported on mesoporous silica nanospheres (MSNS) with uniform center-radial mesopore channels (∼7 nm). The effects of the electronic and crystal structures of Ag nanoparticles on the adsorption and activation of DMO and H₂ were studied. The characterization results reveal that amino-functionalization of the support enables the silver–silicon catalyst to possess easily accessible highly dispersed Ag active components, lattice defects which are conducive to the adsorption, activation and diffusion of H₂, as well as electron-rich Ag^δ− species beneficial for the adsorption and activation of DMO, thereby endowing it with high activity, selectivity, and stability. In the reaction of DMO to MG, under the conditions of P = 2.0 MPa, T = 220 °C, H₂/DMO molar ratio = 80, and LHSV = 1.0 h⁻¹, the best catalytic state achieved a DMO conversion of 100%, a MG selectivity of 96.6%, a TOF as high as 207, and the MG yield could still remain above 95% after a 250 h lifetime investigation. Our research highlights a promising route for the development of high-performance Ag catalysts used in the syngas to MG process.