Synergistic hydrothermal liquefaction of wheat stalk with homogeneous and heterogeneous catalyst at low temperature

The effect of Na 2 CO 3 , Fe and Na 2 CO 3  + Fe during hydrothermal liquefaction (HTL) of wheat stalk with different temperature and reaction time was investigated in this study. The results indicated that Na 2 CO 3  + Fe can promote the cracking of wheat stalk compared with Na 2 CO 3 or Fe. Meanwhile, higher temperature favored the decomposition of wheat stalk and formation of heavy bio-oil. The highest heavy bio-oil yield was 24.25 wt% and the maximum liquefaction conversion rate was 89.45 wt% in system of Na 2 CO 3  + Fe at 270 °C. The analysis results indicated that longer reaction time could promote liquefaction conversion especially for heavy bio-oil with Na 2 CO 3  + Fe during the process of HTL. GC–MS, UPLC-MS and FT-IR analysis indicated that the major organic compounds in heavy bio-oil were aromatic compounds , alcohols, ketones, alkanes, and aldehydes, among of them aromatic compounds were the most prevalent.