| Biomass is the only renewable energy that can be turned into fuels and chemicals.Pyrolysis liquefaction of preparing bio-oil is a very promising utilization technology of biomass energy. However, the quality of bio-oil with its complex characteristics must be appropriately modified to meet the requirements of application.This article has carried on the catalytic pyrolysis experimental study of catalyst and biomass co-pyrolysis based on the fluidized bed. Then researching the influence of reaction temperature and catalysts on the biological characteristics of oil and phenolics content in the analysis of bio-oil.Selecting diameter of 40-60 particle size corn stalk powder as raw material was for catalytic pyrolysis reaction at 450 ℃, 500 ℃, 550 ℃ and 600 ℃ by acid(HZSM-5) and alkaline catalysts(dolomite and red mud). The effects of the different operation factors such as pyrolysis temperature,catalysts on the yields and distribution of three products and the characteristics of bio-oil were investigated. The results indicated that with the increase of pyrolysis temperature, the gas content increase, carbon residue content reduce, the yield of bio-oil attain the maximum at 550 ℃ in the pyrolysis products. After adding catalysts,the yield of bio-oil fell slightly, it achieved the minimum about 38.66% by using HZSM-5catalyst.Using advanced test and analysis method to analyze the physical and chemical properties analysis of the bio-oil. These properties include moisture content, calorific value,p H. Reaction temperature, there is no significant influence on the calorific value and p H value; As temperatures rise, biological oil increased moisture content in small increments.After adding catalyst, moisture content increased, it is because of the molecular sieve catalyst have larger specific surface area which can provide a large number of small aperture, that is advantageous to the dehydrogenation deoxidization reaction. After adding HZSM-5 catalyst, bio-oil calorific value reduced slightly; On the contrary, the calorific value of bio-oil with dolomite and red mud catalyst had increase. It shows that the role of alkaline catalyst in the biomass pyrolytic liquefaction process is very obvious. From the point of data, catalyst HZSM-5 for bio-oil had no effect on the p H value. However, bio-oil p H increased obviously after adding dolomite and red mud catalyst, the bio-oil p H increases to 5.82 with red mud from 2.54 without catalyst at 550 ℃ especially. This suggests that the dolomite and red mud catalysts had obvious acidity reduction effect in the process of biomass pyrolytic liquefaction.The relative contents of phenolic substances increased with increasing reaction temperature by the FC chemical method. Three kinds of catalysts are conducive to improve the total phenol content, the improvement of the total phenol content by solid base catalyst is much more obvious.Bio-oil composition was analyzed by the FC chemical method and gaschromatography-mass spectrometry(GC-MS), the results show that using chemical method for determination of phenol in bio-oil has a higher relative content than the GC-MS methods. It is mainly due to the part of the macromolecular phenolic cannot be detected by GC-MS. But the relative contents trend of phenolic substances detected by chemical method is same to using GC-MS. Under the action of catalysts polymerization and aromatization reaction have happened breeds into small molecular phenol easily.Reaction temperature is not significant impact on the bio-oil composition, mainly ketones, acid, phenolic. Adding HZSM-5 catalyst can improve the small molecule phenolics content(phenol, methyl phenol); Adding dolomite and red mud catalyst reduce acid substance content significantly, improve the contents of esters, and more conducive to macromolecular aggregation phenolics cracking for small molecule phenolics(phenol,phenol, methyl ethyl phenol). |
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