Aqueous-Phase Dehydration/Hydrogenation of Sorbitol: Identification of Reaction Pathways

Aqueous-phase dehydration/hydrogenation is a promising technology to convert biomass-derived oxygenates into alkanes and oxygenates. The reaction chemistry occurs on bifunctional catalysts that contain both metal and acid sites. We have tested the aqueous-phase dehydration of sorbitol in a continuous flow reactor with a variety of bifunctional catalysts. We have identified a majority of reaction products including: dehydrated sorbitol compounds (isosorbide), polyols, alcohols, cyclic-ethers, ketones, alkanes and CO2. In this presentation, we will show the reaction pathway for conversion of sorbitol into alkanes and oxygenates. These products are produced by a series of reactions including C-C breaking reactions (including decarbonyldration and retro-aldol reactions), C-O bond cleavage (dehydration), and hydrogenation reactions. We will discuss how the reaction conditions (flow rate, pressure, or concentration) and catalysts affect the reaction pathways. We will also discuss other products that could potentially be made by aqueous-phase dehydration/hydrogenation chemistry.