Wood of liquefaction

rv SUMMARY PhD Thesis LIQUEFACTION OF WOOD Melek YILGIN Fırat University Graduate School of Natural and Applied Science Department of Chemical Engineering 2000, Page: 119 In today's World of rapidly increasing population, it has been very important to use natural sources in an efficient way to ansure human needs. In the industrialized countries consumption of wood as a fuel has been reduced to minimal levels. But the wood is still in widely use as a fuel in our country, Turkey. The coal, which is very abundant in our country, could be consumed instead of wood, and the wood could be converted into valuable chemically products. The direct liquefaction of materials originated from plants, known as biomass, pyrolysis and liquefication under high pressure are appropriate techniques for chemical conversion process of wood. In this study, the liquefaction of slurry prepared from wood and water was examined to develop the conditions of steps applied for liquefaction of wood in order to increase the amount of liquid product. This examination consisted of preparation andrheology of the slurry, distribution of particle size, the effects of temperature and catalysts on liquefaction of slurry and investigation of quality and quantity of the slurry and oil obtained during liquefaction. For this reason, the techniques of TGA, FTIR and GC were used to find out the quality of the oils. The effect of alkali catalysts on liquefaction was examined in the presence of Na2C03 and K2C03, whareas the effect of acid catalysts was examined only in the presence of formic acid (HCOOH). Both dry and wet-grinded wood was used to prepare slurries. Oswald-de Waele model was found to be the most suitable flow model for wood and water mixtures, and viscosities of mixtures increased rapidly with the amount of wood. The size distribution of the wood particles in the slurry obtained by grinding wood in water, showed firstly size englargement by swelling of fibrous structure due to water penetration and then size reduction of swollen structure by grinding depending on the duration of grinding. However, The size distribution of the wood dust which obtained by dry-grinding of the wood indicates that there may be some agglomeration during the grinding due to electrostatic forces or during measurement of particle size causing to increase the fraction of larger particles. In the experiments undertaken to search the effects of acidic (HCOOH) and alkaline (Na2C03, K2CO3) catalysts on the liquefaction, acid catalysts were found to be more effective than alkali catalysts in terms of both the amount of oil and carbon contents of the oils. Thus, only acid catalyst was then used in the foregoing experiments to determine the effects of other parameters such as temperature, liquefaction time and particle size on liquefaction. The results obtained from the experiments carried until maximum oil yields at different temperatures (250, 300 and 350°C) and times showed that oil yields increasedVI with temperature. But, at each temperature oil yields firstly increased to a maximum value then cotinuously decreased. It was found that the particle size did not effect the properties of the oil obtained, but using the wood dust as a slurry in water increased the amount of oil comparing with the amount obtained from the runs undertaken with sawdust and wood powder. The penetration of the water into the wood particles, occuring previously during wet grinding of the wood was thought to be the cause of this increment. The FTIR spectrums of the oils obtained from time-dependent experiments done seperately at three temperatures (250, 300 and 350°C) were almost similar and they contained all of the basic oxygen-bearing functional groups. Thermal gravimetric analyses (TGA) of the oils have shown that some condensation reaction occured during thermal decomposition, while GC analyses indicated that the oil had undergone a number of polymerization and oxidation reactions in time. Key words: Wood, Liquefaction, Rheology, Pyrolytic oil