| With the increasing demand for energy and the rising atmospheric greenhouse gas levels, renewable energy should be widely explored to renovate the energy source structure and keep sustainable development safe. Biomass as a clean and renewable energy resource has become more and more attractive to industry in the past 20 years. It is estimated to contribute 10-14% of the total energy supply in the world. In addition, biomass has zero net emission of CO2 and has very low contents of sulfur and nitrogen, which gives lower emissions of SO2, NOx than conventional fossil fuels. Therefore, the widely exploration of biomass has great potential for alleviating energy problems, such as the greenhouse effect and the depletion of fossil energy sources.A new methord"Direct deoxy-liquefaction"was introduced in this paper, which was different from fast pyrolysis and high pressure liquefaction. Experiments were conducted in an airtight reactor without adding H2, and other carrier gas. In this liquefaction process,the most oxygen in biomass was released in the forms of CO and CO2,thus, high heating value oil can obtained with a low oxygen content and high H/C ratio. Several catalysts were selected and prepared to control the distribution of the aromatic compounds and long-chain alkanes in the liquid oil.In this paper, the deoxy-liquefaction mechanics of cellulose, hemicellulose and lignin were studied. The liquid oil obtained from cellulose was mainly composed of phenols, benzenes, furans and cyclopentanones. Abundant phenol derivatives were obtained from high lignin content biomass, for example walnut shell (75.88%). Furthermore, long chain alkanes may come from the extractive part of biomass was confirmed due to the analysis of extractive content and the yield of alkanes. In addition, cellulose, hemicelluloses and lignin mixed with staggered in biomass, they affect each other in deoxy-liuqefaction processes for steric hindrance.Four usual biomasses: soybean stalk, walnut shell, sunflower shell, peanut shell was chosen for preparing liquid oil in this paper. Gas chromatography-mass spectrometry (GC-MS) with the National Institute of Standards and Technology (NIST) 98 MS library was used to analyse the composition of liquid oil, while the functional groups analysis was carried out by Fourier transform infrared spectroscopy (FTIR). The element contents of biomass and liquid oil was analyzed by elemental analysis. So the liquid oil components can be analysed qualitatively and quantitatively and the mass distribution of products was done. The liquid oil with a maximum yield 19.2%wt and H/C molar ratio of 1.99 and higher heating value (HHV) of 46.9 MJ/kg was obtained at 450℃from sunflower shell samples via deoxy-liquefaction. Furthermore, the oil analyzed by GC-MS was mainly composed of benzene derivatives, phenolic derivatives, and alkanes (C7-C19). It has more potential to be a substitute for petroleum fuels than the oil that consisted mainlyof aldehydes, ketones, esters, and ethers. On the other hand, the productions of high lignin content biomass are mainly char, and the liquid oil is manily composed of phenolic derivatives. So, high lignin content biomass can be used to prepare phenolic derrivetives and other chemicals. The gaseous products were H2,CO,CH4 and CO2. The major gas product was carbon dioxide (75-90%) for all samples, suggesting that great amount of oxygen atoms have been removed during the process. In conclusion, direct deoxy-liquefaction can limited the oxygen content in the liquid oil and increased the high heating value significantly. It would provide a new prospect for the utilization of biomass.
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