Study On The Catalyst For Producing More Light Olefines By Catalytic Cracking Process

With developing our country economy fast, the requirement of the market for ethylene and propylene is growing rapidly. At present, the ethylene and propylene are producted by steam thermal cracking. However, the production of propylene by stream thermal cracking has been unable to meet with the growing market for the needs of propylene. In addition, there are still problems for steam thermal cracking. For example, energy consumpting and equipment investment is too high, the materials of cracking could choose the range of small, the environmental pollutions seriously and so on. Catalytic cracking technology could solve the above problems, so catalytic cracking technology is becoming a hot research, mainly in terms of process and catalyst.In this article ZSM-5 zeolite is synthesized on the surface of Kaolin microspheres successfully, and it was characterized by XRD,SEM,NH3-TPD,BET. It was studied in a small experimental device of fixed-bed microreactor with other catalysts of mechanical mixing zeolite/Kaolin, in order to explorate and develop a catalyst for light olefins.The first, ZSM-5 zeolite is synthesized in the hydrothermal system by the materials of waterglass,aluminumsulfate, butylanmine, sulfuric acid. The impact of ZSM-5 zeolite synthesis conditions is studied, studied in detail in the crystallization temperature, crystallization time, pH, Si/Al, the amount of template, the concentration. The results show that a higher crystallinity ZSM-5 zeolite can be synthesized, as the pH is 10, the Si-Al ratio is 60, the crystallization time is 24h, crystallization temperature is 180℃, n(H2O)/n(SiO2)=30, the amunt of template is 5.5ml.The second, ZSM-5 zeolite grew successfully on the surface of Kaolin microsphers, the ZSM-5 overgrowth on Kaolin was characterized by XRD,SEM,NH3-TPD,BET. The characterization results showed that the surface of Kaoline grew more microscopic crystal of ZSM-5, it is about 3μm, a new catalytic cracking catalysts with an inexpensive multi-channel had been successfully synthesized.The third, a diesel raw material occurred catalytic cracking in the small fixed bed micro-reactor, HZSM-5/WQ. Hβ/WQ.HY/WQ mechanical mixed catalysts of 5% 10% 15% three content mass fraction were studied at 500℃,550℃,600℃. The reactivity of the ZSM-5 overgrowth on Kaolin was studied at 500℃,550℃,600℃.The results showed that:The yield of propylene, the ZSM-5 overgrowth on Kaolin>ZSM-5/WQ mechanical mixed catalysts>β/WQ mechanical mixed catalysts>Y/WQ mechanical mixed catalysts.The forth,in the small fixed bed micro-reactor, n-butane as the reaction to raw materials, the gas speed in the raw materials and the temperature of reaction were studied on catalytic cracking reaction. Under certain conditions, compared to thermal cracking with quart sand as filler and catalytic cracking, the results showed that the ZSM-5 overgrowth on Kaolin had the best reaction performance. The optimal reaction condition was at mass flow speed of the n-butane 5h-1 and 600℃. The conversion was 89.71% at mass flow speed of the n-butane 5h-1 and 600℃, the yield of light olefins reached 40.46%, the yield of dry gas reached 38.49%.