Study On Catalytic Liquefaction Of Lignite In Supercritical Ethanol System

The effect of ethanol and Ru/C catalyst on liquefaction was found.When the absence of ethanol,the total conversion was low,the yield of liquefied oil was only 4.26%,and the liquefaction was difficult to be carried out.In the absence of catalyst,the yield of liquefied oil was 74.71%,which shows the effect of ethanol for hydrogen,when high temperature cracking lignite,it can stabilize the free radicals and promote the conversion of intermediates to oil and gas.In the process of lignite liquefaction,adding catalyst?50%?and ethanol can get oil yield was 64.76%.Although there is reduction compared with absence of catalyst,but the total conversion rate is larger,degree of conversion is higher and the amount of residue is smaller.The liquefaction of lignite 2,which was also collected from Zhaotong,Yunnan,was liquefied.It was found that under the same reaction conditions,the liquefaction yield of coal 1 was better,the gas yield of coal 2 was higher.There is a large difference in the yield of lipids and phenols in the components,but they also have large conversion activity,which can achieve the desired conversion effect by changing the reaction conditions of coal 2.Therefore,the influence of parameters such as reaction temperature,residence time,catalyst addition amount and ratio of alcohol to coal on the direct liquefaction of lignite was systematically investigated.And qualitative and quantitative analysis of gas-solid-solid three-phase products of catalytic hydrogenation of lignite was carried out.The main conclusions are as follows:?1?Through a series of experiments,it was found that lignite supercritical ethanol catalyzed hydrotreatment of liquefaction was studied at a temperature of 400 ?.under the condition of a residence time of 60 min,the ratio of alcohol to coal was 9 and 25%addition of Ru/C,the yield of liquefied oil can reach 77.88%,the total gas conversion rate is 9.39%and the solid residue rate is 5.92%.?2?In the process of optimizing liquefaction,it is found that the reaction temperature is the key factor affecting the liquefaction.With the increase of temperature,the liquefaction rate increases first and then decreases.With the extension of reaction time,the yield of liquefied oil gradually increased,but reached a certain degree,the impact of time is not obvious,especially under the condition of high temperature.the time to achieve the highest oil yield will be shortened.?3?The role of amount of catalyst to the oil yield was small,further increasing the amount of catalyst will reduce oil production,however,the GC-MS and FT-IR analysis of liquid products show that the catalyst can promote the decarbonylation or decarboxylation of oxygen-containing functional groups,reduce the oxygen content and increase the yield of LCAs by hydrocracking and hydrogenation,reducing impurity atoms and PH As and improving the quality of the oil.?4?Increasing the amount of ethanol in the reaction system can promote liquefaction,but should avoid the gasification induction conditions.The gas products are mainly CH4,CO and CO2 and a small amount of H2,C₂H₄,C2H6,the influence of temperature and the amount of catalyst on the gasification was significantly,but the high gas production is not conducive to liquefaction.Therefore,the reasonable control of reaction conditions,the conversion effect should be controlled in the liquefaction range effectively.?5?Through the element analysis of the solid residue and comprehensive liquid phase analysis,it was found that the oxygen element,nitrogen element were reduced and sulfur element was the opposite,indicating the desulfurization effect was better,but the denitrification was much more difficult than deoxidation and desulfurization,and it required violent reaction conditions and catalyst.In the process of coal conversion,N in the coal can produce amines,nitriles,nitrogen-containing heterocycles and nitrogen-containing polycyclic compounds.Based on the above studies,the catalytic liquefaction of lignite is expected to be obtained under supercritical ethanol system with Ru/C as catalyst,mild reaction temperature and shorter reaction residence time.Through the control of the key factors affecting the reaction,with the help of kinetics and other aspects of analysis to provide basic data and experimental scientific basis for the relevant technology promotion.