Bimetallic RhRe/C catalysts for the production of biomass-derived chemicals

Pretreatment temperature affects the activity of a RhRe/C catalyst for Csingle bondO hydrogenolysis of 2-(hydroxymethyl)tetrahydropyran and for dehydration of fructose. Catalytic activities for both Csingle bondO hydrogenolysis and dehydration were observed to decrease with an increase in pretreatment temperature from 393 to 723 K, which coincides with a decrease in the number of sites quantified using NH3 temperature-programmed desorption. Results for the characterization of RhRe/C using X-ray absorption spectroscopy (XAS) are consistent with the formation of Rh-rich particles with a shell of metallic Re islands after reduction at 393 K, which shows penetration of Re into the nanoparticle with increasing reduction temperature. No evidence of rhenium oxide was found from the Re LIII-edge XAS spectra after reduction at temperatures above 363 K or under aqueous operando conditions. The apparent acidity of RhRe/C is suggested to be generated from the activation of water molecules over Re atoms on the surface of metallic Rhsingle bondRe particles.