The growth mechanism and application in isoamylene oligomerization of MCM-22 zeolite

MCM-22 zeolite synthesized by utilizing the hexamethyleneimine as the organic structure directing agent has a wide range of applications. For the growth mechanism of the typical sample, on the macro level, XRD, FT-IR, and SEM are used to confirm the epitaxial growth of the intercalation structure. On the micro level, eight different T sites of the zeolite are completely distinguished as well as the guidence of hexamethyleneimine on T 1 , T 2 , T 3 and T 5 sites has been demonstrated through DFT calculation and solid-state nuclear magnetic resonance. A series of MCM-22 zeolites display the good catalytic stability and dimerization selectivity. The synergy of hexamethyleneimine and amphiphilic organosilane optimizates the mesopore and acidity of the sample effectively, which makes the selectivity and yield of dimerization product exceed 94.8 % and 85.0 % after 12 hours respectively. At the same time, the carbon deposition decreases from 3.38 % to 3.13 %. This work provides a theoretical basis for the growth mechanism and application in olefin oligomerization of MCM-22 zeolite.