Ethanol and Acetaldehyde Decomposition on Co(0001): The Effect of Hydrogen Atom on C-O Bond Scission

Fischer-Tropsch synthesis (FTS) with Co-based catalysts has attracted renewed interest in recent years due to its potential applications to produce transportation fuels. However, experimental investigations about the FT mechanism at the atomic level, especially for the essential C-O bond scission step, are rarely carried out. Using the temperature-programmed desorption method, we have investigated the mechanism of C-O bond scission in the decomposition of ethanol (C2H5OH) and acetaldehyde (CH3CHO). We have clearly found that the H atom attached to the C-end of the CO molecule is significant for C-O bond scission accompanied by CH3 at the C-end. Otherwise, C-C bond scission will occur facilely if only a CH3 group is attached to the C-end of the CO molecule. These results indicate that CH3CHO may be an important intermediate in FTS for C-O bond scission to produce C2Hx or for C-2+( )oxygenate production. Moreover, the H atoms on the Co(0001) surface could largely inhibit the dehydrogenation of the H atom at the C-end of CO, leading to an enhancement of C-O bond scission. The results for the first time demonstrate that, except the CH3 radical at the C-end of the CO molecule, an additional H atom at the C-end of the CO molecule and the surface H atoms play vital roles in promoting the C-O bond scission in the FT process as well.