Study On Liquefaction Mechanism And Liquefaction Of Wheat Straw Mixed With Polyester In Supercritical Ethanol

With the development of the society, the demand for oil, natural gas and coal is increasing. The large consumption of fossil fuel cause the greenhouse effect that pollutes the air and the environment get worse day by day. To change the status quo , the governments have to pay attention to the research on the renewable energy. The supercritical technology is well developed recent years. Because of the excellent characteristics,it is widely used in the area of pharmaceutical industry,chemical industry and material industry. What more, it is also used on the research of the biomass which has broad prospect. The wheat straw, waste in agriculture, produced hundreds million every years in china and numbers of plastic garbage that produced by industry and people is not only bad for the environment but also be a waste as solar energy resource and oil resource.In this article, we mix polyester with wheat straw and then liquefied them in supercritical ethanol. It transforms the agriculture wastes and industry wastes into renewable energy. Through the experiment ,we analysis the influencing factors of liquefaction yield, including reaction temperature, reaction time ,dosage of the polyester and the solid-liquid ratio.We found that when the temperature is 275℃,the solid-liquid ratio is 1:6,the dosage of the polyester is twice of the straw and the reaction time is 30min, the liquefaction rate of the organic compounds in straw is up to 88.87% and the liquefaction rate of the mixture is up to 96.52%. With the GC-MS Analysis of liquefaction products, we detect more than 30 kinds of substances, including phenol and the derivatives of phenol, ester, organic acid and aldehyde.We study the influence of two catalysts on the liquefaction rate. We found the sodium carbonate which is weak alkaline has little action to the liquefaction rate. When the dosage of sodium carbonate is 10% of the straw, the action is best while the liquefaction rate only increased 5.2%. Compare with the sodium carbonate, SO₄^2-/Fe₂O₃ solid acid is better. When the dosage is 9% of the straw, the action is best. The liquefaction rate increased 7.81%.Study on the effect of circulating liquefaction to the liquefaction rate of the straw.It is learned that circulating liquefaction leads to the high rate.After twice circulation,the rate is 17.03% higher than no circulating.The impregnant restrain the carbonization of the straw during circulating,and make the reactor easier washing.What more, circulating liquefaction make industrial continuous production possible.When terminate the reaction in sudden by the fast cooling device of the high-pressure reactor, we get the intermediate products in different temperatures. Then analysis the residues by Infrared Spectroscopy and compare with the straw powder, we learn the transformation of chemical bond. After that, we analysis the liquefaction products by GC-MS and get the components.By doing these, we could learn the liquefaction mechanism. It provides theoretical basis to process optimization and control of the process of reaction.