Liquefaction of woods belong to some tree species and determination of composition of liquid product

Wood liquefaction is a biomass conversion process in which liquid products are formed by degradation of wood components in a suitable chemical added solvent at high temperature and pressure conditions. In this thesis, wood samples obtained from oak (Quercus brantii), acacia (Robinia pseudoacacia) and pine (Pinus bruita) trees were used. Wood samples were ground into particle size of less than 0.5 mm, dried at 105 °C in drying oven and liquefied in aqueous medium. It was investigated effects of experimental parameters such as temperature, catalyst, time and wood concentration on yields of oil products obtained from the liquefaction of wood samples. In addition, yields of oil products obtained from the liquefaction of air dried and oven dried wood samples were compared. Liquefaction experiments were performed by using a semi-batch reactor at different temperatures (240, 280, 320 and 350 °C), wood concentrations (wt/wt % 5, 10 and 15) and liquefaction times (0, 0.25, 0.5, 1.0 and 1.5 hour). Formic acid, sodium carbonate and zinc chloride were used as catalyst in experiments. Oil products were extracted with diethyl ether and analyzed with aid of FTIR spectroscopy and combined gas chromatography-mass spectroscopy (GC-MS) system in order to determine the oil compounds. In addition, viscosities of oil products were measured by using a rotational viscometer and non-Newtonian behavior was modeled by using the power law.It was observed that yields of oil products increase with increasing temperature up to a certain value and then decrease with temperatures higher than that value. Highest oil yields were obtained at the temperature values of 280-320 °C. It was observed that oil yields decrease with increasing the liquefaction time and the maximum yield was obtained at 0 hour. It was observed that while amounts of liquid products decreases the amounts of gas products increases with increasing the temperature and time. In all experiments, the oil yields increased with increasing the wood concentration. Zinc chloride catalyst plays more effective role on liquefaction process comared to the other catalyst. Highest and lowest oil yields were obtained from acacia and oak wood, respectively. It was observed that oil yields depend on lignin content of wood samples and decrease with increasing lignin content. It was also observed that there is no significant difference between yields of oil products obtained from air dried and oven dried wood samples. It was determined that the oil products mainly consist of phenolic compounds. Beside those main compounds there are aldehyde and carboxylic acid compounds. Viscosities of oil products obtained from the liquefaction experiments were determined as a function of shear rates and it revealed that fluids are pseudo plastic. It was observed that viscous behaviors of oils obtained from different woods vary depending on amount and type of phenolic compounds.