Study On Synthesis And Catalytic Performance Of Zeolite ZSM-22

Paraffin isomerization technology can be used to improve octane number and reduce the long-chain alkanes pour point of base oils, it is a more economical way of high-production octane gasoline and high-quality lubricating oil. Isomerization dewaxing catalyst primarily used to be metal-zeolite bifunctional catalyst, the zeolites which have 10-membered ring structure and medium acidity display better catalytic performance on the Paraffin isomerization.ZSM-22 zeolite has linear 1-dimendional 10-membered ring openings with channel 4.5×5.5A which parallel the direction of (001). In this paper, we use hydrothermal method to study the synthesis influence factors of ZSM-22 such as ratio of materials, crystallization temperature and reaction time, the crystal morphology, surface area, acidity and acid strength of ZSM-22 zeolite were characterized by X-ray diffraction, infrared spectroscopy, transmission electron microscopy and NH3-TPD methods. The preparation of bifunctional catalytic was get from Pt loaded after the ZSM-22 zeolite though acid modified which will be applied to the dodecane hydroisomerization reaction.The results show that:1. The methods of dynamic synthesis and static seeded synthesis will get purity and high crystallinity ZSM-22 zeolite, compared with crystallization time, dynamic synthesis is better than static seeded.2. Using silicon as silicic acid source, high crystallinity ZSM-22 zeolite was synthesized under static seeded method. The optimum conditions of synthesis is:90(SiO2):1(Al2O3):27(DHA):27(K+):3600(H2O), crystallization temperature 160℃, the crystallization time 48h, seed contents is 1000ppm-3000ppm.3. XRD, SEM, IR, N2 adsorption, NH3-TPD were used to characterizatize the structure, crystallization appearance, specific surfance area, acidity.4. The isomerization of dodecane catalyzed by Pt/ZSM-22 was studied. The effects such as reaction temperature, reaction pressure, space velocity, hydrogen hydrocarbon ratio was inverstigated. the optimal reaction conditions were:reaction temperature 305℃, reaction pressure 2MPa, space velocity of 1, hydrogen hydrocarbon ratio of 15. At above contions, the conversion of dodecane is 89.09%, the selectivity of isomerization, monobranched paraffins and cracking is 34.29%, 29.71% and 65.71%, respectively.