A DFT study on dimethyl oxalate synthesis over Pd_(ML)/Ni(111) and Pd_(ML)/Co (111) surfaces

摘要

Pd-ML/Ni(1 1 1) and Pd-ML/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) - 2COOCH(3) - DMO is the favorable route and 2COOCH(3) - DMO is the rate-determining step on Pd-ML/Ni(1 1 1) and Pd-ML/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 Pd-ML/Co(1 1 1) Pd-ML/Ni(1 1 1) Pd(1 1 1). Moreover, DMO generation is superior to the formation of by-product DMC over Pd-ML/Ni(1 1 1) and Pd-ML/Co(1 1 1) surfaces. Therefore, Pd-ML/Ni and Pd-ML/Co bimetallic catalysts are proposed to be promising candidates for DMO formation.