Syngas to ethanol on MoCu(2 1 1) surface: Effect of promoter Mo on C O bond breaking and C C bond formation

Abstract

The mechanism of syngas to ethanol on MoCu(2 1 1) surface has been researched by density functional theory (DFT) calculation, and the effects of Mo as a promoter on C O bond breaking and C C bond formation have been discussed. Calculations show that Cu-Mo atoms constitute the active sites on MoCu(2 1 1) surface after Mo atom being served as a promoter of Cu catalyst. Compared with Cu(2 1 1), MoCu(2 1 1) has two improvements. Firstly, CH 3 is the most advantageous monomer on the MoCu(2 1 1) surface, which provides abundant CH 3 intermediate for syngas to ethanol. Secondly, the C C bond is formed mainly by inserting CHO into the abundant CH 3 , and the generated CH 3 CHO through multiple steps of hydrogenation to generate C 2 H 5 OH. The key of the promoter Mo on the MoCu(2 1 1) surface also has been verified by the analysis of its electronic properties. Differential charge density shows that the massive electron transfer from Mo to Cu, projected density of states ( p DOS) shows that the electron transfer from Mo to Cu makes the d-band center of MoCu(2 1 1) nearer to the Fermi level, these indicate that the MoCu(2 1 1) catalytic capacity increased. The addition of Mo in the Cu-based catalyst not only can effectively solve the problem of C O bond breaking, but also promote C C bond formation. About the influence of Mo content on C O bond breaking and C C bond formation, compared with MoCu(2 1 1), the DFT results and the d-band center of Mo 2 Cu(2 1 1) show that the increase of Mo content could not promote the synergistic effect of Cu/Mo on the generation of ethanol more effectively.