Analysis of liquid and solid products from liquefaction of paulownia in hot-compressed water

Biomass has been proposed to be an alternative source of fuels for industrial applications. The liquefaction of paulownia was studied in hot-compressed water with iron catalyst at temperatures ranging from 280 to 360 °C, using a 1000 ml stainless steel autoclave with a magnetic stirrer. With an increase of the reaction temperature, the yield of heavy oil increased and then decreased. The maximum yield of heavy oil of 36.34 wt.% was obtained at 340 °C. The experimental results show that the reaction temperature significantly influenced the process of biomass liquefaction. The liquid products and solid residues produced at various reaction temperatures were analyzed using Fourier transform infrared (FTIR) spectrophotometer and the heavy oil got at 340 °C were analyzed using gas chromatograph with mass selective detector (GC–MS), respectively. The analytical results show that the heavy oil and water-soluble oil is complicated compound. The water-soluble oil mainly contains carbohydrates, acetic acid, alcohols, aldehydes and pyran derivatives. In addition, the heavy oil mainly consists of phenol and its derivatives, ketone, long-chain carboxylic acids/esters, benzene derivatives and long-chain alkanes.