Promoting chi-Fe5C2(100)(0.25) with copper - a DFT study

The role of copper in iron based Fischer-Tropsch catalysts was investigated using DFT with chi-Fe5C2(100)(0.25) as a model surface. The presence of atomic copper on the iron-rich chi-Fe5C2(100)(0.25)-surface is more favorable than its presence in surface. Nevertheless, the segregation of copper from the surface yielding fcc-Cu remains an exergonic process. Carbon monoxide at a coverage of 2.2 CO per nm(2) stabilizes atomic copper on this surface. The presence of copper results in the redshift in the stretching frequency of adsorbed CO. The mobility of copper atoms was investigated on chi-Fe5C2(100)(0.25) in the presence of CO. The hopping frequency is reduced due to the presence of CO, although never enough to avoid formation of fcc-Cu on a shorter time scale than typically required for the formation of hydrocarbons in the Fischer-Tropsch synthesis.