Microwave enhanced pyrolysis of gumwood

Abstract

Microwave pyrolysis of biomass has gained increasing interests due to the fact that microwave heating provides a volumetric heating and instant heating at improved heating efficiencies compared with conventional heating techniques. In this study, microwave-enhanced pyrolysis of gumwood was carried out at 500 °C with silicon carbide as a microwave absorber. Conventional pyrolysis of gumwood was also studied under the same temperature conditions as that of microwaveenhanced pyrolysis. The yields of pyrolytic products, morphology of bio-char, and composition of bio-oil and bio-gas are analyzed by using Scanning Electron Microscope, Gas Chromatograph/Mass Spectrum and Gas Chromatograph respectively. The yields of pyrolytic bio-oil and bio-gas under microwave heating are 8.52 and 73.26 wt.% respectively, which are higher than the products obtained via conventional methods under similar operating conditions. In microwave-enhanced pyrolysis, numerous carbon nano tubes (CNTs) are formed on the surface of the bio-char. The bio-oil obtained by microwave pyrolysis has simpler constituents compared with conventional pyrolytic bio-oil. The proportions of syngas (H2 + CO) and methane (CH4) in the gas product produced under microwave-enhanced pyrolysis are 62.52 and 22.41 vol.% respectively, which are higher than that of gas product from conventional pyrolysis. It is clear that microwave-enhanced pyrolysis has shown the potential as an alternative method for biomass conversion.