High yields of C2-C6 mono-alcohols can be produced from solid biomass by supercritical methanol depolymerization and hydrodeoxygenation (SCM-DHDO in a single catalytic step using non-precious metal (CuMgAl) catalysts. The cellulose and hemicellulose portions of the biomass are converted into C2-C6 mono-alcohols while the lignin portion of the biomass is converted into aromatic and cyclohexyl monomers and dimers. Cyclohexyl monomers and dimers are produced from solubilization and depolymerization of lignin in methanol and stabilized via hydrogenation reactions over copper sites on the catalyst. Methanol is incorporated into the lignin monomers and dimers via alkylation of the aromatic ring or via aldol condensation between methanol and cyclic ketones. The pathway to C2-C6 mono-alcohols from cellulose occurs through rapid C-C coupling reactions between methanol and diols via aldol condensation followed by C-C scission between vicinal alcohol groups to produce two mono-alcohols. Experiments with glucose-13C6 show that methanol is incorporated in all liquid products accounting for approximately 30-40% of the carbon yield from cellulose. Analysis of the liquid products with Fourier transform ion cyclotron resonance MS (FT-ICR MS) measured C7-C12 partially oxygenated species with 2-6 double bond equivalents which could not be detected via GC. We have demonstrated this technology in both batch and continuous flow reactors. The catalyst has been shown to be stable for over 100 h time on stream in a continuous flow reactor. Recycling of CO and H2 produced during reaction decreases the amount of methanol that is reformed into unreacted gases. Overall carbon yields of alcohols are 108% (due to methanol incorporation into the products).

Production of alcohols by biomass depolymerization and hydrodeoxygenation in supercritical methanol over a CuMgAl oxide catalyst

2019 Spring National Meeting

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