Abstract: Camphorwood sawdust from industrial processing was treated by vacuum pyrolysis for bio-oil preparation. The response surface methodology (RSM) was employed to optimize the process for maximum yield of bio-oil. All factors that affected bio-oil yield, including pyrolysis temperature, reaction pressure and heating rate, were investigated. Furthermore, the physicochemical properties of the bio-oil obtained from vacuum pyrolysis at the optimal conditions were evaluated. The chemical composition was also examined using Fourier transform infrared (FT-IR) and gas chromatograph/mass spectroscopy (GC-MS). The results showed that these three factors had obvious effects on bio-oil yield. However, the interaction between them was not remarkable. The optimal conditions for bio-oil yield were pyrolysis temperature 474.0 ℃, reaction pressure 7.5 kPa and heating rate 20.0 ℃/min. At this condition, the bio-oil yield could reach 50.25% close to 50.41%—the predicted value. Water content and high heat value of bio-oil was 21.35% and 26.82 MJ/kg, and its dynamic viscosity at room temperature, density, pH value and carbon residue content were 3.85 mm²/s, 1.08 g/cm³, 3.24 and 5.54%, respectively. Bio-oil from camphorwood sawdust was a complex mixture, which involve aromatics (26.30%), alcohols (12.14%), carboxylic acids (8.45%), aldehydes (26.17%), ketones (14.24%) and esters (1.18%). It also contained some specific organic compounds, which could be further extracted for industrial raw materials. Further study on enhancing the properties of bio-oil should be performed to ensure economic feasibility in future.

Key words: camphorwood, vacuum pyrolysis, response surface methodology (RSM), bio-oil, composition analysis