Mechanism of Preferential Hydrogenation of Hydroxymethyl Group to Aldehyde Group in 5‐Hydroxymethylfurfural over W2C‐Based Catalyst.

A W4C2 cluster was used to model a W2C catalyst with the armchair model of activated carbon support, noted as W4C2/AC. Over W4C2/AC, the mechanism for the hydrogenation of both −H2OH and −CHO groups in 5‐hydroxymethylfurfural (HMF) was theoretically studied in tetrahydrofuran at GGA‐PBE/DNP level. 5‐Methylfurfural was the major product from only hydrodehydration of the −CH2OH group, whereas 2,5‐dihydroxymethylfuran was the minor product from the hydrogenation of both −CH2OH and −CHO groups. The rate‐determining steps were concerned with the −C(H)2−H bond formation for the hydrodehydration of −CH2OH group, and the −(OH)(H)−H bond formation for the hydrogenation of −CHO group. Kinetically, W‐sites promoted the hydrodehydration of −CH2OH group and inhibited the hydrogenation of −CHO group. This stemmed from the strong Lewis acidity of W‐sites, which easily accepted the lone‐pair electrons of the oxygen atom in the −C(OH)(H)− group, making −C(OH)(H)−H bond formation hard, and hampering the hydrogenation of the −CHO group. [ABSTRACT FROM AUTHOR]