Synthesis Of MCM-22 Zeolite And Its Application In Catalysis

Zeolites are of scientific and technological interests because of their applications involving ion change, adsorption (for separation), and catalysis, and advanced porous host-guest materials. Due to the structure that contains two independent 10-member ring pore and 12-member ring super-cage pore, MCM-22 has been studied extensively as a shape selective catalyst for many reactiuons. In the dissertation, the synthesis, modification, catalytic properties of MCM-22 zeolite were systematically studied. Subsequently, microporous carbon nitride was synthesized using zeolites as templates. The main results in this thesis are summarized as follows:1. MCM-22 zeolite has been synthesized with hexamethyleneimine in presence of cationic surfactant cetyltrimethylammonium bromide. The morphology of MCM-22 zeolite obtained in presence of surfactant changed greatly, and the size of zeolite particles decreased obviously and the small particles aggregated to large particles.2. MCM-22 zeolite with SiO2/Al2O3 ratios in the range of 20-500 has been synthesized through a process of structural conversion. Disproportionation of toluene was carried out over MCM-22 zeolite with different SiO₂/Al₂O₃ ratios, and the catalytic performance has been correlated to the Bronsted acidity of MCM-22 zeolite,and also the HMCM-22 zeolite with different SiO₂/Al₂O₃ ratios was used as support of molybdenum based catalyst in methane dehydroaromatization.4. Acid sites located on the external surface of HMCM-22 zeolite have been modified by chemical liquid deposition of tetraethoxysiliane. Effect of silylation on the shape selectivity of HMCM-22 zeolite was examined via toluene disproportionation, and found that deactivation of Bronsted acid sites on the external surface can enhance the para-xylene selectivity.5. Microporous carbon nitride was first synthesized with microporous zeolite as template using ethidene diamine and carbon tetrachloride as chemical precursors. The obtained microporous carbon nitride has high surface area and narrow pore sizedistribution. The pore size of microporous carbon nitride allows to be tailored by selecting different zeolites as templates.