Design And Synthesis Of ZSM-5/SAPO-11 Composite Molecular

As the poor quality of raw oil and the market demand increases for clean fuel and high quality chemical materials worldwide,hydrocracking technology developing rapidly.And the research of catalyst carrier is particularly important for hydrocracking technology.SAPO-11,with excellent performance of isomerization,can be used as catalyst carrier.And ZSM-5 has outstanding cracking activity and strong ability to resist poison of alkaline N from alkaline molecules.In the research,we want to synthesize the composites of ZSM-5 and SAPO-11,which have high isomerization activity,excellent cracking performance and strong ability to resist poison.In this paper,we synthesized SAPO-11 and ZSM-5 through hydrothermal method and seeded method respectively.The previous research has shown aging treatment could reduce particle size of SAPO-11.By improving the content of silicon to synthesize high silicon aluminium ZSM-5 would cause the low relative crystallinity.So it should be combined with other related conditions.We adapt the secondary growth method to synthesize SAPO-11/ZSM-5 and ZSM-5/SAPO-11 composites.The pretreatment of SAPO-11 is necessary for the synthesis of SAPO-11/ZSM-5.Therefore,we used a variety of pretreatment method,and ureaformaldehyde resin filling showed the best effect on the block for the hole of SAPO-11.ZSM-5 with different Si/Al ratio and different grain size were used to synthesize ZSM-5/SAPO-11.The results showed that high Si/Al ratio of ZSM-5 were more likely to maintain its structural stability in the weak acid environment of SAPO-11 and ZSM-5 with small grain size zeolite could improve the specific surface area of SAPO-11.In addition,we also studied the influence of mass ratio of ZSM-5 and SAPO-11,which indicated that when m(SAPO-11)/m(ZSM-5)was 1:3,the relative crystallinity of the two molecular sieves were closest.The crystallization time of SAPO-11 had little effect on the relative crystallinity of ZSM-5,and the relative crystallinity of SAPO-11 was highest when the crystallization time of SAPO-11 was 24 h.In the process of hydrocracking,Pt@ZSM-5/SAPO-11 showed a highest selectivity towards isomer products among the cracking products,while Pt@ZSM-5/SAPO-11 exhibited nearly a same capability with Pt@ZSM-5 in anti-alkaline nitrogen compound contamination.