Pyrolysis of Delonix Regia and Characterization of Its Pyrolytic Products: Effect of Pyrolysis Temperature

Pyrolysis of a rarely researched biomass feedstock, Delonix regia (DR), at different pyrolysis temperatures carried out in a tubular reactor at an atmospheric pressure of one bar. In addition to the fuel and physical properties of produced bio-oil and bio-char, extensive advanced characterization of these products, viz. Fourier transformation infrared (FTIR), GC-MS, proton (¹H) nuclear magnetic resonance (¹H NMR), X-ray diffraction (XRD), etc. is also performed as applicable to different products. The main emphasis of this work is on both quantitative and qualitative analysis of pyrolytic bio-oil and bio-char obtained from DR at 500–700 °C. In this range of temperature, higher heating value (HHV) of bio-oil found to be varying between 20.88 MJ/kg and 25.70 MJ/kg following increasing trend with the temperature. However, HHV of bio-char observed to be almost unaffected by pyrolysis temperature, and it is approximately 36 MJ/kg. The density of bio-oil found to be decreasing from 0.95 g/cc to 0.88 g/cc as the pyrolysis temperature increases from 500 to 700 °C; however, pH is found to be almost unaffected by the pyrolysis temperature changing only slightly from 3.4 to 3.3. Furthermore, the moisture content of bio-oil is also found to be unaffected by the temperature variations. From the GC-MS chromatograms of bio-oils, it is found that benzene is highest area % (with 14.6%) and phenol, 2,6-dimethoxy is the second-highest area % occupying component (with 10.5%) in bio-oil obtained at 600 °C of pyrolysis temperature. This result indicates that the DR feedstock is also an excellent resource for producing value-added green chemicals.