SYNTHESIS OF ZSM-22/-23 INTERGROWTH ZEOLITE WITH MIXED-TEMPLATE

1. SYNTHESIS OF ZSM-22/-23 INTERGROWTH ZEOLITE WITH MIXED-TEMPLATE Bingchun Wang*, Zhijian Tian, Peng Li, Lei Wang, Yunpeng Xu, Wei Qu, Huaijun Ma,Zhusheng Xu, Liwu Lin(Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R.China) *Corresponding author: e-mail:wangbc@dicp.ac.cn, Tel: +86-411-84379286,Fax: +86-411-84379151 Abstract: In In the present work, ZSM-22/-23 intergrowth zeolite was synthesized with mixed-template method of ethylamine and ethylenediamine, and characterized by XRD, SEM, and BET. The experimental results revealed that ZSM-22/-23 intergrowth zeolites were synthesized using mixed templates with different ratio of ethylamine to ethylenediamine. The as-synthesized products had higher crystallinity than those using single template of ethylamine or ethylenediamine, and they possessed different properties of pore diameter, surface area, and morphology in contrast to ZSM-22 and ZSM-23. Mixed-template method broadened the range of SiO2/Al2O3 of starting mixture and restrained the growth of cristobalite. Introduction ZSM-22(TON topology) and ZSM-23(MTT topology) are two high-silica aluminosilicate zeolites with unidimensional ten-membered channels with diameter 0.550.44nm and 0.520.44nm, respectively. Because of their structurally identical subunits the framework structures of ZSM-22 and ZSM-23 are closely related to each other[1], which indicates the intergrowth zeolite of ZSM-22 and ZSM-23 formed in certain conditions. The intergrowth zeolite is new topology structure zeolite different from zeolite bound zeolite[2] or composite zeolite[3], which has uniform structure in framework. Experimental Silica sol was used as silicon source and aluminum sulfate as aluminum source, respectively, and with mixed templates of EA and EDA, at the temperature of 150~190℃ for 2~5 days with molar ratios of starting gels at SiO2:Al2O3:EA:EDA:H2O = 100:x:y:z:4500, where x varied from 0.66 to 2.0, (y+z) fixed at 67, respectively. Table 2. the results of hydroisomerization of n-C12 over ZSM-22/-23 intergrowth zeolite supported precious metal catalysts Results and Discussion Using mixed templates of EA and EDA, the intergrowth ZSM-22/-23 zeolite was synthesized with SiO2/Al2O3= 100, despite of the ratio of EA/EDA, whereas single template of EA or EDA resulted in the formation of cristobalite as main product with small amount of the intergrowth zeolite in the same conditions. The experimental results of n-dodecane show that the intergrowth ZSM-22/-23 zeolite possesses excellent catalytic hydroisomerization performance of long-chain paraffin. Furthermore, even decreasing the ratio of SiO2/Al2O3 to 60, ZSM-22/-23 was still successfully synthesized, While using one template of EA or EDA the samples only contained minor ZSM-22. Table 1. Experimental conditions and the results of he products obtained [(EA+EDA)/SiO2=0.67] To further investigate the catalytic performance of the intergrowth ZSM-22/-23 zeolite in the application for the petroleum industry, we carried out the isodewaxing experiment of lub oil. The results was listed in Table 3. It was shown that the intergrowth ZSM-22/-23 zeolite was suitable for the systhesis of lub oil. Table 3. the results of hydroisomerization of lub oil over ZSM-22/-23 intergrowth zeolite supported precious metal catalysts Fig.2 SEM images of zeolite ZSM-22 and zeolite ZSM-23 References 1. Marler B, Deroche C, Gies H, et al,J Appl Cryst, 26(4):636,1993 2. Hendriksen D E, Mohr F D, et al, US20020137977,20023. Chen H L, Shen B J, Pan H Fm, Chem Lett , 32(8): 726,2003 Fig.1 XRD pattern of ZSM-22/ZSM-23 intergrowth Fig.3 SEM images of ZSM-22/ZSM-23 intergrowth