Study On Preparation Of Catalyst In Fluid Bed Over Biology Ethanol Dehydration To Prepare Ethylene And Its Technology

This paper aim at developing new catalyst and rebuild reactor in the reaction of ethanol dehydration prepare ethylene. Explored the two catalyst system-modified bentonite and modified HZSM-5 over ethanol dehydration to prepare ethylene in self-design fluid bed. The catalysts' structure were characterized by XRD,SEM,FT-IR,Py-IR,XPS,TG,BET, and associated with the catalytic activity. The modified mechanism of catalysts were also discussed. Via compare the structure of fresh catalyst and deactivation catalyst, finding out the reason of deactivation. Based the reason of deactivation, refresh the catalyst.The following results and conclusion were obtained from these studies. (1) A set of fluid bed reactor was designed, using the general catalyst such as alumina to dehydrate ethanol to prepare ethylene, some good results have been received. It proved that the reactor is reliable, the fluid bed reactor has apply state patent (patent apply number: 200710009681.8); (2) The modified bentonite and modified HZSM-5 were used as catalysts to dehydrate ethanol to prepare ethylene. We selected HZSM-5 as base substrate, introduced into V,P to prepare co-modified catalyst (V-P/HZSM-5). When the ratio of P and V is 7.5, calcination temperature is 300℃, reation temperature is 220℃, ethanol flow velocity is 0.1 ml·min^-1, the catalyst amount is 3 g, the ethanol conversion and ethene selectivity can reach 96.9% and 96.5%, respectively. Further more, the use life of the catalyst can reach about 40 days (terminate the reaction when the conversion is decreased to 85%); (3) Use V-P/HZSM-5 as catalyst over biology ethanol dehydration, the results show that when the reation temperature is 220℃, biology ethanol flow velocity is 0.1 ml·min^-1, the ethanol conversion and ethene selectivity can both reach 90%; (4) Probe into reason of deactivation in catalyst, we found out coking is the primary reason. The best refresh conditions are: distilled water flow velocity is 0.3 ml·min^-1, the temperature of ditilled water is 400℃, disposed time is 3 hours. The refresh catalyst in catalyzing ethanol dehydration, the ethanol conversion and ethene selectivity can reach 90.6% and 91.7%, the ethanol conversion and ethene selectivity merely drop 6.3% and 4.8%, respectively. The use life of the refresh catalyst still can last 400 hours. So, it prove that through vapour refresh the catalyst can renew its catalytic capability; (5) Combined with the physicochemical structure characterization of V-P/HZSM-5 and its catalytic capability, the modified mechanism of catalyst was suggested: V,P in the process of modify HZSM-5, P atom enter the framework of HZSM-5, partly replace Si in [SiO₄] tetrahedron, and that form a kind of mix atomy molecule sieve with cage shape structure, this kind of structure not only stabilize the framework of molecule sieve, but also promote for V atom enter into the framework of molecule sieve, so that V can exist steadily in framework, improve the catalytic capability of molecule sieve efficiency.