Synthesis of ZSM-22/ZSM-23 intergrowth zeolite as the catalyst support for hydroisomerization of n-hexadecane

ZSM-22/ZSM-23 intergrowth zeolite was successfully synthesized by hydrothermal method with diethylamine and dimethylamine as co-structure directing agents at a dimethylamine/diethylamine molar ratio of 24. The physicochemical properties of ZSM-22/ZSM-23 intergrowth zeolite including the crystallinity, crystal morphology, texture and acidity were determined by XRD, FE-SEM, TEM, N₂-physisorption, NH₃-TPD, Py-FTIR, and so on; the performance of Pt/ZSM-22/ZSM-23 catalyst prepared by impregnation in the hydroisomerization of n-hexadecane was then investigated. The results indicate that the ZSM-22/ZSM-23 intergrowth zeolite displays the needle-like morphology with the topological structures of both ZSM-22 and ZSM-23, which is rather different from pure ZSM-22 and ZSM-23 and their mechanical mixture. After loading 0.5% Pt, the bi-functional Pt/ZSM-22/ZSM-23 catalyst exhibits excellent performance in the hydroisomerization of n-hexadecane, with a much higher yield of i-C₁₆ products (dominated by mono-branched isomers) than those obtained over Pt supported on ZSM-22 and ZSM-22 and their mechanical mixture.