Thermal Conversion of Carboxylate Salts and Catalytic Ketone Hydrogenation

Biomass as a source of energy and chemicals has gained importance due to the decreasing oil reserves, fluctuating oil prices and environmental concerns. Ethanol, a common fuel derived from biomass, is now used as a blend in conventional transportation fuels, however ethanol energy density (Higher Heating Value (HHV) = 29.84 MJ/Kg) is quite low compared to conventional gasoline (HHV = 46.53 MJ/Kg). This reduces overall energy density of the ethanol blended gasoline. Alcohols such as propanol (HHV = 33.6 MJ/Kg) and butanol (HHV = 37.3 MJ/Kg) have higher energy densities and can also be used as blends in conventional transportation fuels. Production of three to seven carbon alcohol 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 the 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 the desired longer-chain alcohols. In this thesis, two unit operations viz. thermal decomposition of carboxylate salts to ketones and hydrogenation of ketones to alcohols were studied. In the thermal decomposition unit operation, decomposition temperatures and decomposition products of various pure and biomass-derived carboxylate salts were determined. In the hydrogenation unit operation, the catalyst for ketone hydrogenation was identified. Further, the activity of ruthenium supported on activated carbon for hydrogenating ketones was explored using acetone as the model compound. A simple kinetic model accounting for the effects of temperature, H2 pressure, and acetone concentration was developed for acetone hydrogenation with the Ru/C catalyst