Bio-oil production via catalytic supercritical liquefaction of Syrian mesquite (Prosopis farcta)

Supercritical liquefaction of Syrian mesquite (Prosopis farcta) stems was performed to produce bio-oil in methanol and acetone without and with (zinc chloride, sodium hydroxide) catalyst at three different temperatures (255, 275 and 295 degrees C) using a high pressure (40 MPa) autoclave reactor for 75 min reaction time. The effects of process parameters including temperature, catalyst and solvent on liquefaction yields were investigated. The optimum conditions for liquefaction were provided with zinc chloride as catalyst and acetone as solvent at 295 degrees C. According to the results, the highest conversion of 77.96% and liquid yield of 49.67% were obtained in acetone at 295 degrees C in the presence of zinc chloride. The produced bio-oils were analyzed and characterized by the methods including elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography mass spectrometry (GC-MS). EA indicated that the most of the raw material's energy was recovered in bio-oils with HHVs between 20 and 34 MJ/kg. GC MS showed the formation of diverse compounds including aliphatics, aromatics, oxygenated and nitrogenated compounds. Acetone bio-oils were enriched in aromatics, ketones and esters while methanol bio-oils contained sugars and carboxylic acids. (C) 2015 Elsevier B.V. All rights reserved.