Abstract:
CuFe catalyst is an important catalyst for higher alcohols formation from syngas. In order to gain mechanistic insight into the reaction, spin-polarized density functional theory calculations were performed to investigate the growth mechanism of carbon chains on CuFe (100) and (110) surfaces. The calculated results show that Cu atoms prefer to aggregate rather than homogeneously disperse on the Fe (100) and (110) surfaces. With the increase of Cu atoms, the surface energy decreases gradually, suggesting that the surface tends to be more stable. The dominant activation mechanism of CO on CuFe (100) surfaces is ascribed to a H-assisted CO dissociation via CHO intermediate, which is then progressively hydrogenated to form CH
2O and CH
3O. Subsequently, CH
3O is dominantly hydrogenated to form CH
3OH. The pathway of carbon chain growth is found to be CHO rather than CO insertion. The activation mechanism of CO on CuFe (110) surface is found to be similar to that on CuFe (100) surface. The pathway of CH
3O formation is CO+3H→CHO+2H→CH
2O+H→CH
3O. On the CuFe (110) surface, CH
3 formation is more thermodynamically favorable than CH
3OH, which leads to the production of more CH
3 for CO insertion to form C
2+ higher alcohols. This research offers mechanistic insight into improving the production of higher alcohols on CuFe catalyst.