Thermochemical conversion of Phellinus pomaceus via supercritical fluid extraction and pyrolysis processes

Abstract

Thermochemical conversion processes such as supercritical fluid extraction and pyrolysis are used for producing biofuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250–400°C temperature range under high pressure (4–5MPa). Pyrolysis method is the process of decomposition of the organic materials with heat in the inert atmosphere or vacuum nature between high temperatures (350–800°C). Two thermochemical processes, supercritical fluid extraction and slow pyrolysis, were used to produce bio-oils and biochars from Phellinus pomaceus. Supercritical fluid extraction trials were performed in a cylindrical reactor (75mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 270 and 290°C. Pyrolysis experiments were performed in a fixed-bed tubular reactor without and with same catalysts used in liquefaction at the temperatures of 400, 500 and 600°C with constant heating rate (40°C/min). The effects of process variables including temperature and catalyst on product yields were investigated. Product yields and composition of bio-oils were evaluated and compared for supercritical fluid extraction and pyrolysis. The produced liquids at 290°C in supercritical liquefaction and at 500°C in pyrolysis were analyzed and characterized by elemental, GC–MS and FT-IR. 60 and 72 different types of compounds that were identified by GC–MS obtained in acetone and ethanol respectively whereas pyrolysis liquids had 90 different types of compounds. Bio-oils from supercritical liquefaction were composed from various organics including aromatics, nitrogenated and oxygenated compounds while phenolics were major compounds in pyrolysis liquids. Bio-oils obtained from supercritical liquefaction were found to have higher heating values and superior fuel properties compared to pyrolysis bio-oils.