Production and separation of phenols from biomass-derived bio-petroleum

Cotton stalk was directly deoxy-liquefied in the air-proof stainless steel reactor heated at the rate of 10 °C/min to the final temperature of 450 °C. The bio-petroleum was analyzed by using FTIR and GC–MS, which showed that bio-petroleum had low oxygen content, high H/C molar ratio and heating values, as well as the especially high content of phenols (relative content: 55.21%). The bio-petroleum was rectified under vacuum, and the distillate of 180–260 °C with phenols (relative content: 78.84%) was obtained by controlling the boiling point. The phenols were further recovered by mixing with sodium hydroxide solution and hydrochloric acid, followed by the extraction with dichloromethane. The dichloromethane layer was separated and distilled under vacuum with the protection of nitrogen. Thus, the high-purity phenol derivatives, such as phenol, cresols, guaiacol, 4-methyl guaiacol and syringol were obtained. The results indicated that the extraction by organic solvents was effective in separating and purifying phenols from bio-petroleum.