Lignocellulosic biomass has received widespread attention as environmentally benign feedstock for fuels. Biomass consists of cellulose, hemicellulose and lignin and has rather high oxygen content. Different techniques for the conversion of lignocellulose to liquid fuels have been suggested in the literature. In this thesis the emphasis is on the utilization of biomass-derived platform molecules. Platform molecules include eg. ketones, alcohols and carboxylic acids.
In the literary section different deoxygenation and C-C coupling reactions for the conversion of biomass-derived platform molecules to larger hydrocarbons have been reviewed. Reaction routes for upgrading of the platform molecules 5-hydroxymethylfurfural, 2-furaldehyde, levulinic acid and some monofunctional compounds have been presented. These paths comprise mainly dehydration, hydrogenation, aldol condensation and ketonization. Heterogeneous catalysis,
particularly bifunctional supported catalysts, dominates in this field.
The selectivity that may be achieved with homogeneous catalysts is seen as highly desirable and served as the main incentive for the experimental work. Furthermore, the lack of publications in the area of homogeneously catalyzed C-C coupling of biomass-derived compounds also motivated for the work. Herein, 1st row transition metal acetates were utilized as catalysts for the ketonization of biomass-derived levulinic acid and other carboxylic acids. Some experiments were conducted with lignin as well. Reactions were performed under microwave heating or reflux conditions. Products were analyzed by GC-MS, GC-FID, NMR and FTIR. Combinatorial chemistry made it possible to conduct up to twelve reactions simultaneously. More than 160 reactions were performed in less than two months' time. The main product in many of the reactions was aromatic phthalic acid mono 2-ethylhexyl ester. Some other interesting products included hexadecanoic acid, 2,6-dimethyl-2,5-heptadien-4-one, diisooctyl and dibutyl phthalate. Despite small amounts of the products, their presence proves that various compounds may be produced from biomass by tailoring the catalyst and reaction conditions.
