Bifunctional Ru@N-Doped Mesoporous Carbon Catalysts for Catalytic Transfer Hydrogenolysis of Bio-Derived Polyols

The depleting fossil fuel reserves and increasing problems of environmental pollution have accelerated the development and utilization of renewable energy. Biomass resources, as the only widely distributed and accessible renewable organic carbon raw materials in the world, have attracted worldwide attention.^{1, 2} In this context, hydrogenation of bio-derived polyols (sorbitol, glycerol, xylitol, etc.) is an important way to convert biomass into high value-added chemicals.³

Aqueous phase hydrogenation process is considered to be the most promising route for biomass conversion. But high temperatures (> 400 ^oC) and high H₂ pressure (> 4 MPa) make the side reactions very intense, leading to poor atomic utilization economics.⁴ The operating conditions of the catalytic transfer hydrogenolysis process are much milder, using H₂ generated from water or renewable resources, so the energy consumption is small, the atomic utilization rate is high (~100%) and the environmental pollution is small.

According to our literature review, it is found that current studies on transfer hydrogenolysis of polyols involve alkaline species as promoters for simultaneous H₂ generation and hydrogenolysis reactions, which unfavorably cause corrosion and additional costs for product separation. In this work, we proposed a series of nitrogen doped mesoporous carbon (NMC) for efficient transfer hydrogenolysis of glycerol to propylene glycol. The unique interaction between Ru-nitrogen sites is key for anchoring of Ru particles on the inner and outer surfaces of the NMC. While metallic sites are active for H₂ production (C-H cleavage), H₂ transfer and hydrogenation (C-O cleavage) properties, the basic sites provided from NMC facilitate C-H and C-O bond cleavage during transfer hydrogenolysis of glycerol. The conversion of glycerol and the selectivity of 1,2-PDO are 45.1% and 46.7% at 200 ^oC , under N₂ atmosphere. Detailed characterization by XRD, XPS, TEM and BET will be conducted to reveal the structural features and correlated with catalytic performances.