Thermal Conversion of Carboxylate Salts (Biomass-to-Mixed Alcohols)

Biomass as a source of energy and chemicals has gained importance due to the decreasing oil reserves, fluctuating oil prices and environmental concerns. Production of higher alcohol liquid fuels via acidogenic digestion and chemical upgrading of industrial biomass streams offers many advantages over sterile fermentation processes such as lower capital cost, no need for sterility or genetically modified organisms, and ability to produce a variety of chemicals such as carboxylic acids, ketones, esters, and alcohols.

Carboxylate salts formed during acidogenic digestion of biomass can be thermally-converted to ketones. The ketones can then be hydrogenated to form higher mixed alcohols which are fungible fuels and can be used as blending agents in transportation fuels. In the current work, hydrogenation of dimethyl ketone and methyl ethyl ketone in various solvents is studied using an activated carbon supported ruthenium catalyst and compared to previous results using Raney nickel. Reaction rates are significantly higher for the Ru catalyst, and conversion of dimethyl ketone to 2-propanol is autocatalytic. The presence of water also enhances the reaction rate for both ketones studied.