Effect of template content on the physicochemical characterization and catalytic performance of SAPO-11 for the hydroisomerization of n-tetradecane

Different SAPO-11 molecular sieves have been synthesized hydrothermally using mixed template of di-n-propylamine (DPA) and di-iso-propylamine (DIPA) by varying the template content or the ratio of DPA/DIPA. SAPO-11 samples were characterized using X-ray diffraction (XRD), N2 adsorption, NH3-temperature-programed desorption (TPD) and 29Si MAS NMR, and evaluated towards n-tetradecane skeletal isomerization. The results indicated that the template had strong influence on the crystallinity, the Si distribution and the acidity of SAPO-11. The samples prepared at template content of 1.5 and w (DPA) of 66% possessed small silicon domains and large amount of Si(n Al) (0 < n < 4) sites, and the catalysts prepared from these samples showed highest catalytic activity in the hydroisomerization of n-tetradecane because of its high acidity.