Low temperature microwave-assisted pyrolysis of wood sawdust for phenolic rich compounds: Kinetics and dielectric properties analysis

Abstract Microwave-assisted pyrolysis of wood sawdust for phenolic rich compounds was carried out between 400 and 550 °C in a batch reactor. An efficient preparation of liquid products was observed at 500 °C with a yield of 58.50%, which was similar to conventional fast pyrolysis. The highest concentration of phenolic compounds in liquid product reached up to 78.7% (area) in which the alkoxy phenols contributed 81.8% at 500 °C. Microwave thermogravimetric analysis using KAS method was used firstly to investigate the low-temperature pyrolytic behaviors and activation energy. The results indicated that effective pyrolytic range was 250–400 °C and average activation energy was 42.78 kJ/mol, which were 50–100 °C and 50–100 kJ/mol lower than conventional pyrolysis, respectively. Analysis on dielectric properties of pyrolytic products confirmed that accelerated pyrolysis and low temperature were attributed to the formation of instantaneous “hot spots”.