Microwave enhanced pyrolysis of gumwood

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. Microwave-enhanced heating has become one of the research focuses attracting widespread concerns. 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 conditions of microwave-enhanced pyrolysis. The yields of pyrolytic products, morphology of bio-char, and composition of bio-oil and biogas are analyzed by using Scanning Electron Microscope, Gas Chromatograph / Mass Spectrum and Gas Chromatograph respectively. According to the Table 1, 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. In microwave enhanced pyrolysis, numerous carbon nano tubes (CNTs) are formed on the surface of the bio-char, as shown in Figure 1. These CNTs are grown from pyrolysed round particles without the use of specific catalysts, substrates and source gases. 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 microwave pyrolytic gas product are 62.52 vol.% and 22.41vol.% respectively, whose high heating value are 30% higher than that of conventional pyrolytic gas. It is clear that microwave enhanced pyrolysis has shown its potential as an alternative method for biomass conversion.