Supercritical methanol depolymerization and hydrodeoxygenation (SCM-DHDO) of biomass is a technology to produce C2–C9 alcohols in a single reaction step. Previous research has shown that this technology is effective in batch reactors but produces large amounts of undesired CO and H2 gas from the reforming of the methanol that make the process economically infeasible. In this work, we show that methanol reforming can be minimized to provide the stoichiometric amount of H2 required for hydrodeoxygenation by recycling the product gases. We also show that methanol can be synthesized during the SCM-DHDO process with a sufficient cofeed of CO and H2. In addition, we demonstrate that the catalyst is stable for more than 100 h time on stream in a continuous packed bed reactor using glycerol as a model feedstock. The alcohol yields from glycerol in the fixed bed exceeded yields from batch reactions. In a single pass system, the conversion of cellulose and maple wood to alcohols was obtained by first solubilizing in methanol and then converting to monoalcohols over a fixed bed of catalyst.

Biomass conversion to alcohols using supercritical methanol depolymerization and hydrodeoxygenation (SCM-DHO) with CuMgAl mixed metal oxide is a promising process for biofuel production.

Precise control of electron density at catalyst active sites enables regulation of surface chemistry for optimal rate and selectivity to products. Here, an ultrathin catalytic film of amorphous alumina (4 nm) was integrated into a catalytic condenser device that enabled tunable electron depletion from the alumina active layer and correspondingly stronger Lewis acidity. The catalytic condenser had the following structure: amorphous alumina/graphene/HfO2 dielectric (70 nm)/p-type Si. Application of positive voltages up to +3 V between graphene and the p-type Si resulted in electrons flowing out of the alumina; positive charge accumulated in the catalyst. Temperature programmed surface reaction of thermocatalytic isopropanol dehydration to propene on the charged alumina surface revealed a shift in the propene formation peak temperature of up to ΔT(peak)~50 ⁰C relative to the uncharged film, consistent with a 16 kJ/mol (0.17 eV) reduction in the apparent activation energy. Electrical characterization of the thin amorphous alumina film by ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling microscopy (STM) indicates the film is a defective semiconductor with an appreciable density of in-gap electronic states. Density functional theory calculations of isopropanol binding on the pentacoordinate aluminum active sites indicate significant binding energy changes (ΔBE) up to 60 kJ/mol (0.62 eV) for 0.125 e- depletion per active site, supporting the experimental findings. Overall, the results indicate that continuous and fast electronic control of thermocatalysis can be achieved with the catalytic condenser device.