Study On Support Properties Of Selective Hydrogenation Ring Opening And Cracking Catalysts For Bicyclic Hydrocarbons

In this thesis,a series of Ni-W/ASA-Al₂O₃ catalysts and Ni-W/USY-Al₂O₃ catalysts were prepared by equal volume impregnation method for the Ni-W active components,using amorphous silicon aluminum（ASA）and USY zeolite as support modified materials respectively.The physical and chemical properties of catalysts and supports were characterized by low temperature static N₂ adsorption capacity method,X-ray diffraction（XRD）technique and the temperature programmed desorption of ammonia（NH₃-TPD）.Decalin and naphthalene were selected as model compounds.The effect of ASA content on selective ring opening reaction of decalin was investigated on the fixed-bed hydrogenation microreaction equipment,and so was the the effect of USY zeolite content on hydrocracking reaction of naphthalene.Results showed that all the prepared supports belonged to the mesoporous materials.With the increase of ASA（or USY zeolite）content,the specific surface area of both supports and catalysts increased,while the pore size distribution ranged in 4¹0 nm,and the total acid amount of catalysts gradually increased.The crystal structure of ASA（or USY zeolite）in the supports and catalysts remained intact,and the metal components were well dispersed on the surface of catalysts.The increase of ASA content in the supports was advantageous to improve the conversion of decalin.The conversion of decalin gradually increased with the rise of the reaction temperature,under the reaction conditions of 310³70℃,3.0 MPa,volume space velocity of1.0 h^-1 and H₂/Oil（v/v）of 500:1.At the same temperature,the conversion of decalin increased significantly with the increase of ASA content,and the yield of selective ring opening products increased slightly.However,the target product contents were still low and the cetane number was lower even than that of the reactant.Thus,the purpose of improving the cetane number of the feedstock by selective ring opening using modified ASA has not been achieved.The increase of USY zeolite content in the supports can effectively promote the hydrocracking of naphthalene.Hydrogenation saturation was the main reaction,and the products were tetralin together with a small amount of decalin,under the reaction conditions of3.0 MPa,volume space velocity of 1.5 h^-1,and H₂/Oil（v/v）of 300:1.The conversion of naphthalene increased with the rise of USY zeolite content in the range of 200²80℃.The hydrocracking degree of naphthalene was intensified within the temperature of 280³60℃,and the selectivity of benzene,toluene and xylene rised with the increase of USY zeolite content.Besides the conversion of U-1 and U-2 catalysts were still higher than 90%though the slight reduction of reaction conversion.Considering both the conversion and the selectivity of target products,the operating conditions were investigated to determine the suitable condition using the optimized U-2catalyst from Ni-W/USY-Al₂O₃ catalyst series.Results showed that the suitable conditions were370℃,3.0 MPa,volume space velocity of 1.5 h^-1,and H₂/Oil（v/v）of 300:1.In this case,the conversion of naphthalene was 96.62%.Furthermore,the selectivity of benzene was 10.66%,and the selectivity of toluene and xylene was 23.38%.