Syngas Conversion to C2 Oxygenates over the Cu/β-Mo2C Catalyst: Probing into the Effect of the Interface between Cu and β-Mo2C on Catalytic Performance

Aiming at probing into the role of the interface between Cu and Mo2C for syngas conversion to C-2 oxygenates over the Cu/beta-Mo2C catalyst, the formation mechanism of C-2 oxygenates from syngas over the Cu/beta-Mo2C catalyst has been systematically investigated using density functional theory calculations. The results show that the CH monomer is the most preferred CHx species formed via the route of CO direct dissociation into C, followed by C hydrogenation to CH; moreover, the Cu/beta-Mo2C(001) catalyst presents higher activity and selectivity toward CH formation instead of CH3OH formation. For C-2 oxygenate formation, CHO insertion into CH to form the C-2 oxygenate CHCHO is the most preferred. Compared to the pure Cu(111) and beta-Mo2C(001), Cu/beta-Mo2C(001) exhibits better selectivity toward CH formation, and has the strong ability of C-C chain growth for C-2 oxygenate formation. On the other hand, the analysis of electronic and structural properties indicates that there is a strong charge transfer between Cu and Mo2C to form a charge-rich region at the interface of the Cu/beta-Mo2C(001) catalyst, which promotes the C-O bond cleavage of CO and CHO to form the CH monomer adsorbed at the interface, and favors the subsequent CHO insertion into CH to form the C-2 oxygenate CHCHO at the interface. As a result, the synergistic effect including the electronic and geometric effect that occurred at the interface between Cu and beta-Mo2C(001) leads to high productivity toward C-2 oxygenates in syngas conversion over the Cu/beta-Mo2C(001) catalyst.