Integration of Homogeneous and Heterogeneous Catalytic Processes for a Multi-step Conversion of Biomass: From Sucrose to Levulinic Acid, γ-Valerolactone, 1,4-Pentanediol, 2-Methyl-tetrahydrofuran, and Alkanes

Abstract

The multi-step conversion of sucrose to various C5-oxygenates and alkanes was achieved by integrating various homogeneous and heterogeneous catalytic systems. We have confirmed that the dehydration of sucrose to levulinic and formic acids is currently limited to about 30–40% in the presence of H2SO4, HCl, or Nafion NR50 in water. Performing the dehydration in the presence of a P(m-C6H4SO3Na)3 modified ruthenium catalyst under hydrogen resulted in the in situ conversion of levulinic acid to γ-valerolactone (GVL). Levulinic acid can be hydrogenated to GVL quantitatively by using P(m-C6H4SO3Na)3 modified ruthenium catalyst in water or Ru(acac)3/PBu3/NH4PF6 catalyst in neat levulinic acid. Formic acid can be used for the transfer hydrogenation of levulinic acid in water in the presence of [(η6-C6Me6)Ru(bpy)(H2O)][SO4] resulting in GVL and 1,4-pentanediol. The hydrogenation of levulinic acid or GVL can be performed to yield 1,4-pentanediol and/or 2-methyl-tetrahydrofuran (2-Me-THF). The hydrogenolysis of 2-Me-THF in the presence of Pt(acac)2 in CF3SO3H resulted in a mixture of alkanes. We have thus demonstrated that the conversion of carbohydrates to various C5-oxygenates and even to alkanes can be achieved by selecting the proper catalysts and conditions, which could provide a renewable platform for the chemical industry.