PhD ceremony: J. Wildschut, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen
Thesis: Pyrolysis oil upgrading to transportation fuels by catalytic hydrotreatment
Promotor(s): prof. H.J. Heeres
Faculty: Mathematics and Natural Sciences
Environmental concerns and possible future shortages have boosted research on alternatives for fossil derived liquid transportation fuels. Biomass is considered a promising alternative due to its abundance and renewability. Various products from different biomass sources have been proposed. Well known examples are biodiesel from plant oils and bioethanol from starch. A potentially very interesting, second generation transportation fuel is pyrolysis oil, obtained by flash pyrolysis of lignocellulosic biomass in yields up to 70 %-wt. In this process, the biomass is heated to temperatures of 400-600 °C in an oxygen free atmosphere for short residence times. As such, the oil is not suitable as a biofuel for internal combustion engines due to its high oxygen content (ca. 40 %-wt) and low pH (ca. 2.5). Upgrading is required to use pyrolysis oil as a transportation fuel.
An attractive option is catalytic hydrotreatment (HDO) at high hydrogen pressure (100-200 bar) and high temperatures (250-400 oC) to remove oxygen in the form of water by means of a catalyst.
This thesis deals with the conversion of pyrolysis oil into a transportation fuel by means of catalytic hydrotreatment. Catalyst research showed that Ru/C is a suitable catalyst. At optimized conditions of 350 °C, a pressure of 200 bar and a reaction time of 4h an oil was obtained at yields of 65 % with a strongly reduced oxygen content. Model compound studies showed that the carbohydrate fraction plays an important role during the process and this fraction is indentified as a source of unwanted solid formation which can lead to catalyst deactivation. Oil has been produced on a kilogram scale at optimized conditions and is tested successfully using an stationary diesel engine.
