A DFT study on dimethyl oxalate synthesis over PdML/Ni(1 1 1) and PdML/Co(1 1 1) surfaces

Abstract

PdML/Ni(1 1 1) and PdML/Co(1 1 1) surfaces were built via Pd atoms substituting the upper one layer atoms of Ni(1 1 1) and Co(1 1 1) surfaces, and have been discussed toward dimethyl oxalate (DMO) synthesis using density functional theory (DFT) calculation and micro-kinetic modeling, which were further compared with the Pd(1 1 1) surface, in order to obtain high cost-efficiency Pd-based bimetallic catalysts. The results suggest that CO + OCH3 → COOCH3 + (CO + OCH3) → 2COOCH3 → DMO is the favorable route and 2COOCH3 → DMO is the rate-determining step on PdML/Ni(1 1 1) and PdML/Co(1 1 1) surfaces, and it is the same as that over the Pd(1 1 1) surface. The energy barriers combining with micro-kinetic modeling analysis show that the catalytic activity toward DMO synthesis follows the trend of PdML/Co(1 1 1) > PdML/Ni(1 1 1) > Pd(1 1 1). Moreover, DMO generation is superior to the formation of by-product DMC over PdML/Ni(1 1 1) and PdML/Co(1 1 1) surfaces. Therefore, PdML/Ni and PdML/Co bimetallic catalysts are proposed to be promising candidates for DMO formation.