The Optimization of Plasma Catalytic Liquefaction Technique for the Conversion of Sawdust into Value-Added Chemicals

Abstract

Non-thermal plasma is an alternative technology of exploiting biomass for efficient production of value added energy carriers. In this study, plasma catalytic liquefaction (PCL) system is successfully developed to achieve rapid and efficient liquefaction of sawdust in the presence of co-solvent polyethylene glycol 200 (PEG 200) and glycerin as well as the acid catalyst H2SO4. The influences of different operating factors such as the catalyst concentration, reaction time, molar ratio of PEG 200 and glycerin and the power supply are investigated in terms of the liquefaction yield and solution temperature, while the roles of the applied voltage and the duty cycle of power supply in the PCL process are discussed in detail. Experimental results show that the sawdust could be completely liquefied into crude bio-oil with a high heating value (HHV) of 19.18 MJ/kg in the mixture containing sawdust and solvent in a ratio of 1/7, and 1 wt.% catalyst H2SO4. Increasing the applied voltage and duty cycle are more efficient giving higher yield of liquid products. Based on the analysis of the processing conditions, suggested that the enhanced performance of the PCL process is linked to the superiority of heating that induced by electric field and the presence of quantities reactive species during the plasma discharge. The physiochemical characteristics of the biomass sample and the liquefied products are interpreted by using elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR) and the identities and concentration of the liquid products are determined by gas chromatography-mass spectrometry (GC-MS).