Hydrothermal liquefaction of lignite, wheat straw and plastic waste in sub-critical water for oil: Product distribution

•Blending ratio of lignite, wheat straw and plastic waste can influence the product distribution during hydrothermal liquefaction.•When the blending ratio of lignite, wheat straw and plastic waste is 5:4:1, there exists synergism effect for oil yield.•Temperature and initial nitrogen pressure can influence the product distribution during liquefaction.•Adding tourmaline during hydrothermal liquefaction could get higher oil yield than that when adding the traditional catalyst.

Product distribution and character of the products during hydrothermal liquefaction of Jingou lignite, wheat straw and plastic waste in sub-critical water are investigated in an autoclave. The effects of blending ratio of lignite, wheat straw and plastic waste, temperature, initial nitrogen pressure and additives on product distributions are also studied. The results indicate that blending ratio of lignite, wheat straw and plastic waste, liquefaction temperature, initial pressure and additives all could influence the product distributions during hydrothermal liquefaction. When the blending ratio of Jingou lignite, wheat straw and plastic waste is 5:4:1, there exists synergism effect for oil yield, and the oil yield and the gas yield are all the highest at this ratio. The total conversion increases when the temperature increases from 260 °C to 300 °C and then decreases. For the oil yield, when the temperature increases from 260 °C to 280 °C, oil yield decreases, while when the temperature increases from 280 °C to 320 °C, the oil yield increases. Moreover, adding tourmaline during hydrothermal liquefaction of lignite, wheat straw and plastic waste could get higher oil yield, higher total conversion and higher quality oil than that when adding the traditional catalyst.