The hydrogenolysis of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is an important catalytic reaction that produce fuel additives from biomass feedstock. The reaction comprises several hydrogenation and hydrogenolysis steps with the several side reactions including the over hydrogenation of furan ring and the hemiacetal formation that leads to the polymerization of HMF into humins. Here we will present our study of this reaction using Ru cluster catalysts in the last three years. Our key understandings are: 1. The pore geometry of the supporting materials significantly affects the performance of the Ru clusters. Bottle neck pore prevent the growth and aggregation of the clusters, leading to the highest activity. Tubular pore has weak confinement effect, which will lead to the formation of nanoclusters outside the pore. 2. The C=O bond is weakened via intermolecular H bonding on the surface of SiO2 support. This can easily lead to the polymerization into humins via hemiacetal formation. To better stabilize 5-HMF, a polyphenylene (PPhen) support is developed to separate individual 5-HMF molecules on the catalysts surface. As a result, the Ru/PPhen shows the highest conversion to DMF compared with Ru/C and Ru/SiO2 catalysts. 3. The recycling of the catalysts for this reaction is not widely reported or understood. We identify the surface aromatic species that covering the Ru clusters after catalysis, presenting a major deactivation pathway. The catalyst can be regenerated by heating under H2 with subsequent heating under air, removing the surface aromatic species and regenerating the Ru clusters.

Hydrogenolysis of 5-hydroxymethylfurfural via Ru cluster catalysts

2019 Fall National Meeting

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