Deoxygenation Of Bio-oil Model Compounds By Catalytic Pyrolysis With Rare Earth Modified Zeolites Catalysts

Bio-oil catalytic pyrolysis has several advantages,such as low captil cost,easy handling and safe controlling.It has been widely used in improving the quality of bio-oil,for fossil fuels and chemicals production.Based on catalytic pyrolysis conditions,the author designed and manufactured the corresponding reaction instruments.The catalytic pyrolysis experiments were taken on a fixed-bed reactor with bio-oil model compounds（diacetone alcohol,furfural,ethyl acetate and guaiacol）,on different types of zeolites.The properties of the catalysts were characterized by BET,XRD,SEM,NH3-TPD and SEM.According to our studies,the efficiency of pyrolysis on bio-oil model compounds was significantly improved with catalysts.Among HZSM-5,HY and MCM-41 catalysts,HZSM-5 had archieved remarkable product distribution and effectively prevented catalyst coking.The chemicals in catalytic pyrolysis liquids concluded aromatic hydrocarbons（benzene,toluene,xylenes,naphthalene）,2-furyl and 2-ethyl-furan.The optimal selectivity of aromatic was obtained on HZSM-5（7.36%）.The different reaction pathways for model compounds had also been discussed,which further founded a theoretical basis for experimental study on bio-oil upgrading.Effect of SiO₂/Al₂O₃ mole ratios（30:1,38:1,50:1 and 80:1）on the properties of catalysts had been investigated.Taking both of catalytic activity and aromatics selectivity into consideration,SiO₂/Al₂O₃ ratio of 50:1 showed an outstanding performance because of its moderate acidity and pore structure.Refer to XRD,the modified（La,Ni and P）ZSM-5 catalysts maintained original MFI framework structure,while La showed admirable hydrocarbon selectivity over the others.Further research on different La loading（0.1wt.%,0.2 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%）indicated that bio-oil model compounds had the lowest coke yield and best aromatics selectivity on 1.0 wt.% La-ZSM-5.The modifications（La,Ce and Ni on HZSM-5 catalysts）decreased specific surface area of the catalysts and contributed to the conversion from Bronsted to Lewis acid site.The Rare Earth（La,Ce）attached on HZSM-5 had higher selectivity of aromatics（46.37%）and degree of partial deoxygenation（21.97%）than any other modified HZSM-5,while the coke yield decreased dramaticly.