Carbon Chain Growth Mechanism of Higher Alcohols Formation from Syngas on CuFe (100) and (110)

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 CH₂O and CH₃O. Subsequently, CH₃O is dominantly hydrogenated to form CH₃OH. 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 CH₃O formation is CO+3H→CHO+2H→CH₂O+H→CH₃O. On the CuFe (110) surface, CH₃ formation is more thermodynamically favorable than CH₃OH, which leads to the production of more CH₃ for CO insertion to form C₂₊ higher alcohols. This research offers mechanistic insight into improving the production of higher alcohols on CuFe catalyst.