Comparative study on the reaction mechanism of 5-hydroxymethyl furfural on Pd(111) and Cu(111)

In this work, a comparative study on the catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) on precious Pd(111) and nonprecious Cu(111) was systematically performed. On the basis of the calculated activation energy (E_a) and reaction energy (E_r), the optimal energy path for the hydrogenation of HMF (F-CHO) into BHMF (F-CH₂OH) on Pd(111) is as follows: F-CHO + 2H → F-CHOH + H → F-CH₂OH; the minimum reaction path on Cu(111) is F-CHO + 2H → F-CH₂O + H → F-CH₂OH. On Cu(111), the formation of F-CH₂OH from F-CH₂O hydrogenation is the rate-determining step because it has the highest reaction energy barrier and the smallest rate constant. The comparison of HMF hydrogenation on Pd(111) and Cu(111) reveals their inherent differences in selectivity, mainly due to the different adsorption configurations of HMF and BHMF, and it was concluded that the nonprecious Cu(111) is a promising hydrogenation catalyst for the production of BHMF from the hydrogenation of HMF.

All plane-wave DFT calculations were performed via the Vienna ab initio simulation package (VASP). The exchange and correlation energies were computed via the generalized gradient approximation (GGA) of the Perdew, Burke, and Ernzerhof (PBE) functional with the projector augmented wave (PAW) method.