Highly Efficient Vapor-Phase Dehydration of Bio-Derived Sorbitol Over a Sulfur-Intercalated Two-Dimensional Vanadium...

Biorefinery technologies that convert sorbitol into platform chemicals like isosorbide without the use of inorganic acids are essential for sustainability and environmentally friendly green chemicals. Here, we investigate mineral acid-free vapor-phase dehydration of sorbitol over a sulfur-intercalated vanadium phosphate (VPO) catalyst. The roles of Brønsted and Lewis acid sites were studied to understand their effect on sorbitol dehydration and adsorption energy. Intercalating sulfur enhances the relative concentration of Brønsted acid sites on the lamellar VPO surface. Density functional theory results indicate that sorbitol adsorption is thermodynamically favorable on VPO catalysts. However, sulfur-intercalated VPO catalysts exhibit a reduced adsorption energy (E_ad) of -0.64 eV, which is approximately 1.5 times lower than that of regular VPO catalysts, as corroborated by kinetic analysis. Notably, the resulting improvement in catalytic performance results in ≥99% bio-derived sorbitol conversion with ≥94% isosorbide selectivity, limiting other anhydrohexitol intermediate.