Synthesis, Modification And Characterization Of Zeolite-KL As Active Component Of Heavy Oil Cracking Catalyst

Since the 1990's, the quality of the global petroleum is trending to inferior and heaviness, and the recoverable oil reserves decreases rapidly. It has become the focus of the recent research to develop a new material of catalytic cracking to apply to the progress of petroleum refining and the petrochemical industry. And it will be very important to releasing the shortness of petroleum resources, adapting to the development tendency of the crude oil.Zeolite L is a particular molecular sieve from the zeolite family. It possesses one-dimensional pore of about 0.71nm aperture. And zeolite L can be used as a catalyst in the process of catalytic cracking, hydro-cracking and isomerization. By virtue of its unique structural and properties, zeolite L has attracted great research interests in its synthesis and characterization. The activity and selectivity of the catalyst depend on the silica-alumina molar ratio and the acidity of the zeolite. To improve its catalyst efficiency, KL-type zeolite needs to be modified by methods of ion-exchange or dealuminization .In this study, powdered silicon dioxide, potassium dioxide and sodium dioxide were used as starting materials to prepare KL-type zeolites. We examined the influence of reaction temperature, time and the content of the seeds on the formation of zeolites. A large scale synthesis was carried out in a 50-litre reactor under the optimized conditions. The KL-type zeolites were characterized by X-ray diffraction, TG-DSC, IR, N₂-BET, SEM, and chemical composition analysis. Treatment of the obtained zeolites KL with a series of ionic exchange and dealuminization led to the final solid products, which were characterized by the X-ray diffraction, TPD (Temperature-Programmed-Desorption), pyridine-adsorption-IR.In the procedure of optimization, the zeolite L is prepared without agitation by heating a gel mixture of the starting materials, in the term of4.2K₂O·Al₂O₃·14SiO₂·195H₂O, in a high-pressure stainless steel autoclave at about 150°C for 20-40 hours under the self-generated pressure. And in the procedure of 50 liter reaction, Zeolite L product is prepared with agitation. The final product is a well-defined crystal:...