Synthesis Of Micro-Mesoporous Composite EU-1 Zeolite By Soft/Hard Template Method

EU-1 zeolite is a kind of one-dimensional channel microporous zeolite with Ten ring channels,unique side pocket structure,and high hydrothermal stability,mainly used in shape selectivity catalytic reaction,such as xylene isomerization,and exhibit excellent catalytic activity.However the microporous channel of EU-1zeolite will affect the diffusion of large molecules in the channel,limiting the further improvement of the catalytic performance of EU-1 zeolite.Compared with conventional EU-1 zeolite,hierarchical EU-1 zeolite with micro–mesoporous structure have large specific surface area and pore size,the large specific surface area can make zeolites exposrd more surface acidic sites,the mass transfer rate can be improved by increasing the aperture and allow reactant molecules enter the zeolite and improve the ratio of utilization of EU-1 zeolite.In this paper,the synthesis method of hierarchical EU-1 was explored,using carbon black and silane coupling agent as the mesoporous template,the hierarchical EU-1 zeolite.1.Synthesis of hierarchical EU-1 zeolite by using carbon black as mesoporous hard template.Using carbon black as hard template,hexamethonium bromide as the organic structure directing agent,sodium aluminate as aluminum source,silica sol as silicon source under hydrothermal conditions in the synthesis of EU-1zeolite,after baking carbon black,hierarchical EU-1 zeolite was obtained.The EU-1 samples were characterized by XRD,SEM,N₂ adsorption-desorption and NH₃-TPD,the catalytic performance of xylene isomerization were evaluated in fixed bed reactor.the results show that the carbon black could be assisted synthesis hierarchical EU-1zeolite,and exhibited excellent catalytic performance in xylene isomerization reaction,The hierarchical EU-1 show excellent catalytic performance of xylene isomerization,catalytic activity and C₈aromatics selectivity increase from 22.71%,89.20%to 23.94%,92.76%.The factors that influence the synthetic hierarchical EU-1zeolite,such as the addition amount of carbon black,the ratio of Si/Al ratio,the ratio of water to silicon and the types of silicon sources were investigated in detail.2.Synthesis of hierarchical EU-1 zeolite by using organosilane as mesoporous soft templateAdopting organosilane as mesoporous soft template,bromide hexamethonium as organic structure directing agent,sodium aluminate as aluminum source,silica sol as silicon source,under the dynamic hydrothermal conditions synthesized EU-1 zeolite,after roasting organosilane,hierarchical EU-1 zeolite was obtained.The hierarchical EU-1 samples were characterized by XRD,SEM,N₂ adsorption,FT-IR and NH₃-TPD to analyze the crystallinity,morphology,surface area,pore size distribution and acidity,the catalytic performance of xylene isomerization were evaluated in fixed bed reactor.The results showed that hierarchical EU-1 zeolites were successfully synthesized,organosilanes have great influence on crystal morphology of EU-1 zeolites,crystal grain size became smaller and accumulation of holes was significantly increased.Compared with conventional EU-1 zeolite,the surface area of hierarchical EU-1zeolite increased by 70%,mesoporous volume increased by103%,thus can greatly reduces the diffusional limitation in isomerization reaction.Catalytic data show that the isomerization activity of hierarchical EU-1 zeolite increase from the 23.83%to 24.09%,the selectivity of C₈aromatics also increase from 75.16%to 84.85%.The effects of organosilanes,such as the type of organosilanes,the adding amount and the reaction state on the synthesis of hierarchiacl EU-1 zeolite were investigated.In this paper,using carbon black as mesoporous hard template and organosilanes as mesoporous soft template,both of them can synthesized hierarchical EU-1 zeolite and has very high practical value.hierarchical EU-1zeolite were synthesized with carbon black and organosilanes as the mesoporous template,which significantly improved the diffusional performance of the zeolites,and provided a way for the preparation of high performance EU-1zeolite.Hierarchical EU-1 zeolite exhibited excellent catalytic performance in the xylene isomerization catalytic reaction and has great application prospect,but the research on hierarchical EU-1 zeolite are very little,the methods of synthesize hierarchical EU-1 zeolite still need to continue to explore and optimize in the future.