Research Of The FCC Gasoline Selective Hydrogenation Desulfurization Catalyst

Fluid catalytic cracking?FCC?is the most important secondary process in oil refining industry in our country.As a result,more than 70% commercial gasoline is FCC gasoline which contains much high sulfur and olefin.To improve the quality of gasoline to meet the China ? standard,it is necessary to upgrade FCC gasoline by dramatically decreasing the sulfur content while maintaining the octane number.Therefore,the selective hydrodesulfurization?HDS?technique,which can decrease sulfur content in FCC gasoline by deeply desulfurization and maintain its octane number by suppressing the olefin saturation reactions,was developed.The key for FCC gasoline selective hydrodesulfurization is to fabricate high quality catalysts which with high activity and selectivity.In this thesis,we prepared a series of supported Co/Mo catalysts by taking ?-Al₂O₃ or TiO₂-Al₂O₃ as the supports,respectively,and investigated the effects of pore structure and the modification of the TiO₂ of ?-Al₂O₃ on the physicochemical properties and its HDS selectivities.The results are as follows:1.A series of supported Co-Mo/?-Al₂O₃ catalysts were prepared via an incipient-wetness technique and the effects of pore structure of ?-Al₂O₃ on the properties and the HDS selectivities of the catalysts were investigated.The results showed that compared with the specific surface area and pore volume,the pore structure and pore size distribution play a critical role in improving the HDS selectivity.The catalyst A4 obtained from SA4 with a larger pore size,a relatively narrower pore size distribution and a more regular pore structure has the best hydrodesulfurization selectivity.2.Using a series of TiO₂-Al₂O₃ composites which contains different amount of TiO₂ as the supports,a series of Co-Mo/TiO₂-Al₂O₃ catalysts were prepared.The resultsshowed that both of the content of TiO₂ and the pore structure of Ti O₂-Al₂O₃ composites affect the HDS selectivity of the catalyst.The catalyst obtained from TiO₂-Al₂O₃ which with a narrow pore size distribution and a moderate Ti O₂ contents has the high hydrodesulfurization selectivity.The effect of TiO₂ content on the physicochemical properties and the catalytic performance of the Co-Mo/TiO₂-Al₂O₃ catalysts prepared by taking Ti O₂-Al₂O₃ composite as the support was investigated.The results showed that with the increase of TiO₂ content in the composites and their-derived catalysts the specific surface area and pore volume decreased gradually,the total acid amount decreased slightly while the acid strength unchanged.The catalyst obtained by taking TiO₂-Al₂O₃ which contains 10 wt.% TiO₂ as the support has the highest HDS selectivity in hydrogenation process with the desulfurization efficiency of 97% and the olefin saturation of 56%.