Microwave induced pyrolysis of biomass

Microwave heating has attracted much attention recently due to its nature of volumetric heating and instant heating. In this study, microwave heating was adopted not only as a heating method but also an approach to enhance the pyrolysis of biomass. Microwave induced pyrolysis was carried out at 500°C with silicon carbide as a microwave energy absorber. Conventional pyrolysis of gumwood was also conducted under the same operating temperature as microwaveenhanced pyrolysis. The yields of pyrolytic bio-oil and bio-gas under microwave heating are 8.52 wt% and 73.26 wt% respectively, which are higher than the products obtained via conventional methods under similar operating conditions. A series tests were performed to compare the difference between the yields of pyrolytic products, i.e. gaseous products (bio-gas), liquid products (bio-oil) and solid products(bio-char). Scanning Electron Microscope (SEM), Gas Chromatograph/Mass Spectrum (GC-MS) and Gas Chromatograph (GC) were used in this study to characterize the morphology of bio-chars, the composition of bio-gas and bio-oil respectively. The bio-oil produced via microwave pyrolysis has simpler constituents compared with that produced via conventional pyrolysis. The proportion of syngas (H2+CO) and methane (CH4) in the gas product produced under microwave-enhanced pyrolysis are 62.52 vol % and 22.41vol % respectively, which are higher than those in the products of conventional pyrolysis. It is clear that microwave-enhanced pyrolysis has shown a great potential as an alternative method for biomass conversion.