Synthesis Of CHA Zeolite And Its Catalytic Performance

Zeolites were very useful catalysts bit in environmental protection and petrochemical.SSZ-13,has a three-dimensional pore system with ellipsoidal-shaped large cages that are accessible via 8-membered ring windows.It has been reported that SSZ-13 zeolite exhibits extraordinary catalytic properties in selective catalytic reduction of NOx with NH3(NH3-SCR)and methanol to olefins.However,synthesis SSZ-13 zeolites are expensive and low yield.In this case,solvent-free route and fluoride media are employed to solve these problems.In chapter two,we report an efficient and rapid synthesis of high silica CHA zeolite with good crystallinity and uniform crystals(ST-CHA),which has been achieved from interzeolite transformation of high silica FAU zeolite in the absence of water solvent but the presence of zeolite seeds and the bromide form of SDA.The absence of water solvent in the synthesis significantly improves the zeolite yield by avoidance of the dissolution of aluminosilicate species in aqueous media,while the addition of zeolite seeds remarkably enhances the crystallization rate under solvent-free conditions.In addition,this route allows for using low-cost bromide form of the SDA.Catalytic tests in the NH3-SCR show that copper-exchanged ST-CHA(ST-Cu-CHA)exhibits comparable catalytic properties to those of Cu-SSZ-13 obtained from the conventional hydrothermal route.In chapter three,high silica CHA zeolite have been syhthesized in fluoride media.Catalytic tests in MTO reaction show that prepared CHA samples have excelent methanol conversion and very high selectivity for ethylene.