Directly converting cellulose into high yield sorbitol by tuning the electron structure of Ru2P anchored in agricultural straw biochar

Abstract

Directly converting cellulose into sorbitol involves efficient synergy of cellulose hydrolysis and glucose hydrogenation in a bifunctional catalyst. High temperature is favorable and efficient for cellulose hydrolysis, but easily causes the excessive hydrogenation of sorbitol. In this paper, we propose a new strategy to appropriately regulate the hydrogenation activity of Ru catalysts by partially shifting the electrons from Ru to P, which could reduce excessive hydrogenation of sorbitol at 180–200 °C and thus enhance the sorbitol yield. The rice straw biochar was used as carrier and Ru2P/C was synthesized for obtaining sorbitol from glucose by hydrogenation. Subsequently, the bifunctional catalyst Ru2P/C–SO3H was prepared for directly converting cellulose into sorbitol, and the relationship between the composition of the as-prepared catalyst and the sorbitol yield was systematically studied. Satisfactorily, 2 wt% Ru2P/C–SO3H gave sorbitol yields of 96% and 64% at 200 °C within 2 h when glucose and cellulose were used as raw materials, respectively. The characterization results and DFT calculations show that the electrons of Ru atoms in Ru2P are partially transferred to P, which weakens the adsorption and activation of H2 and H* on Ru atoms, thus improving the selectivity of sorbitol. Moreover, Ru2P/C–SO3H has a potential ability in natural biomass waste utilization.