Hydrogenolysis of sorbitol to glycols over carbon nanofibers-supported ruthenium catalyst: The role of base promoter

Sorbitol hydrogenolysis over carbon nanofibers-supported Ru (Ru/CNFs) was carried out with different bases (NaOH, KOH, Mg(OH)2, Ba(OH)2, and CaO) to investigate the role of base promoter. The results indicated that all the bases used significantly enhanced the sorbitol conversion while the glycol selectivities varied with the base type and amount. CaO was the best base in terms of glycol selectivity for two reasons. CaO provided OH− for the base-promoted cleavage of C–C bonds, while it also supplied Ca2+ for complexation with the intermediate aldehydes, thus affecting the reaction pathways. We identified an optimum ratio among sorbitol concentration, Ru/CNFs catalyst, and CaO to achieve favorable glycol selectivities in sorbitol hydrogenolysis. Reaction pathways for sorbitol hydrogenolysis into glycols in aqueous solution in the presence of CaO have been proposed based on the mechanistic study.

Graphical AbstractRu/CNF catalyst and CaO dictated the reaction pathways in sorbitol hydrogenolysis to glycols, where CaO served as both base and metal ion source for complexation.Figure optionsDownload full-size imageDownload as PowerPoint slide