Liquid-phase catalytic processing of biomass-derived carbohydrates to intermediate Furan compounds and liquid alkanes fuel

We have developed a multi-step catalytic process that produces liquid alkanes, ranging from C7-C15, by aqueous-phase processing of biomass-derived carbohydrates, thereby providing a renewable source for transportation fuel. The process involves a series of reaction steps starting with acid hydrolysis of polysaccharides to produce monosaccharides, followed by acid-catalyzed dehydration to form carbonyl-containing furan compounds such as 5-hydroxymethylfurfural (HMF) and furfural. Subsequently, these compounds undergo crossed aldol-condensation with other molecules containing carbonyl groups (such as acetone, glyceraldehyde, dihydroxyacetone) over a base catalyst (mixed Mg-Al-oxide) to produce larger organic molecules (>C6) by forming C-C bonds. These aldol-adducts are further hydrogenated in the presence of a metal catalyst (3 wt% Pd/Al2O3) to form large water-soluble organic compounds that subsequently are converted to liquid alkanes by aqueous phase dehydration/hydrogenation over a bifunctional catalyst (4 wt% Pt/SiO 2-Al2O3) containing acid and metal sites. Further, we identified MgO-ZrO2 as a hydrothermally stable, solid base catalyst to perform aldol-condensation reactions in aqueous environments. Then, we developed a bifunctional metal-base (Pd/MgO-ZrO2) catalyst that facilitated a single-reactor design by combining aldol-condensation with the sequential hydrogenation reaction. In addition, we investigated the effects of various process parameters such as reaction temperature and molar ratio of reactants to obtain maximum yields for heavier products.; Furan derivatives, such as furfural and HMF, are essential intermediates for production of liquid alkanes and various polymer applications. We developed a biphasic batch reactor system for the selective dehydration of D-fructose to HMF that operates at high concentrations of fructose (10--50 wt%), achieves high yield (> 80%), and produces HMF in a separation-friendly solvent. The reactor system includes a reactive aqueous phase containing fructose feed and chemical modifiers such as dimethylsulfoxide (DMSO) and poly(1-vinyl-2-pyrrolidinone) (PVP) along with an organic extracting phase (mixture of 7:3 (w/w) MIBK:2-butanol). We optimized the reaction conditions for production of HMF from glucose and fructose and furfural from xylose monosaccharide units by adjusting the pH and DMSO content in the aqueous layer. Using these optimal reaction conditions, various corresponding polysaccharides were processed with equally good selectivities (from 50 to 90%).