Preparation And Property Evaluation Of Y/ZrO₂ Composite Material

The high adaptability to feed,increasing cracking ability and high selectivity for objective products are requiements for catalytic cracking process?FCC?.An elaborate design for FCC catalyst is an essential way to realize these goals.In this paper,the composition of catalyst was regulated to broaden the adaptability of FCC catalyst to all kinds of complex materials.The traditional silicon aluminum oxide carrier and the chemical composition of FCC catalyst were replaced by ZrO₂,by which the ability to resist poisoning of basic nitrogen compound of catalyst have been enhanced and diffusion resistance of reactant have also been reduced for the acid site on the surface and mesoporous structure of amphoteric oxide ZrO₂.The effect of alkalinity to the phase structure of zirconium dioxide precursors have been investigated,through which good-phase structured ZrO₂ composite material have been prepared and the proper prepration methods of ZrO₂ have been found.The research found that dry gel method,sol gel method and in-situ hydrothermal crystallization coupling method all could realize the in-situ growth of Y zeolite on the surface of ZrO₂.The phase structure of ZrO₂ composite material prepared by in-situ hydrothermal crystallization coupling method was best,from the dates of phase structure and specific surface area of product with three prepration methods above.The growth of Y zeolite on the surface of ZrO₂ was fulfilled by Si-O-Zr bond with the in-situ hydrothermal crystallization coupling method.On the basis of the determination of in-situ hydrothermal crystallization coupling method,the effects of alkali adding method,zirconium addition,alkalinity,aging time,crystallization temperature and crystallization time were investigated to the structure and properties of the composite material were investigated.The result showed that owing to the steric-hinerance effect of ZrO_x?OH?_y to silicon aluminum species,the growth of Yzeolite was inhibited.The relative crystallinity of Y zeolite in ZrO₂ composite material and specific surface area of ZrO₂composite material was decreased as the increased amount of zirconium.Alkalinity was another important factor to ZrO₂ composite material.The silicon aluminum species in raw material couldn`t be fully activated at low alkalinity,while the primary structure of Y zeolite could be destroied at high alkalinity.Only under the suitable basicity,Yzeolite and ZrO₂could realize the symplastic growth.The mesoporous retention of ZrO₂ composite material could be up to 87.72%after calcination at 550?,which indicated that ZrO₂ composite material had a good stability of mesoporous at 550?.Evaluation results showed that the selectivity for liquefied gas and light oil was good and Y/Zr O₂ composite material can restrict the generation of coke and dry gas.Besides,activity of ZrO₂ sopport endowed composites strong ability of resistance to poisoning of basic nitrogen compound,which provides the experimental basis for designing novel FCC catalyst.