Effect of the surface acid sites of tungsten trioxide for highly selective hydrogenation of cellulose to ethylene glycol

This work studied a facile and template-free hydrothermal route for controlled synthesis of tungsten trioxide in the form of hexagonal nanorod (h-WO3) and monoclinic nanosheet (m-WO3). The surface morphology, crystal plane, surface bound water, and surface acid sites of the two kinds of WO3 nanocrystals were investigated systematically. They were further evaluated as catalysts for selective cellulose hydrolysis. While both of them exhibited good catalytic performance, h-WO3 was found to be more preferential for ethylene glycol (EG) generation. This catalytic performance relied on both the unique active crystal surface (1 0 0) and surface binding water (WO3-H2O) formed by h-WO3 crystals, which provided more Lewis acid sites for degrading cellulose into EG. Results showed that the highest EG yield reaches 77.5% by a combination of loading 1 wt% Ru on the h-WO3 catalyst.