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

Microwave-assisted pyrolysis of wood sawdust for phenolic rich compounds was carried out between 400 and 550 degrees C in a batch reactor. An efficient preparation of liquid products was observed at 500 degrees 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 degrees 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 degrees C and average activation energy was 42.78 kJ/mol, which were 50-100 degrees 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. (C) 2017 Elsevier Ltd. All rights reserved.