The Study Of ZSM-5 Zeolite On The Reaction Of Methanol To Propylene

Propylene demand is increasing in recent years. The traditional production method of propylene comes from the petroleum route. Now the oil resource is lack day by day. Therefore, the technology of methanol to propylene which is a non-petroleum route has better prospects on development. It is important for MTP to research high performance catalyst at present. It is mainly based on the modification of ZSM-5 zeolite that can change the acidity and pore structure of ZSM-5 zeolite in order to achieve the purpose of optimization of catalyst performance.The frist, the material balance of reactor was examined. The second,under the conditions of the inspection process, it were researched that the influenees of silica alumina ratio, hydrothermal treatment, phosphorus modification, the metal modification were on the reaction of methanol to propylene catalytic performance in the fixed bed reactor. At the same time the catalysts were characterized. The catalyst with best catalytic performance was selected. It was found that with silica alumina ratio of zeolite increased, the selectivity to propylene was increased accordingly, the higher alumina ratio zeolite had a good methanol conversion and higher propylene selectivity. After the appropriate hydrothermal treatment(600℃) to ZSM-5 zeolite, methanol conversion was more than 99% and propylene selectivity was 33.5%, the stability of the catalyst had been significantly improved. ZSM-5 zeolites were modified with different concentrations of phophorus, it was found that the modified ZSM-5 zeolite with the mass fraction of 1% of phophorus had the most obvious catalytic performance. It could better improve the lifespan of the catalyst and obtain a high propylene selectivity. Both the propylene selectivity and the stability of catalyst had been increased significantly to 40% and 80h from 26.8% and 45h over the parent ZSM-5 zeolite. After ZSM-5 catalyst was modified by metal Co/Ce/Zn/Ni, Co modification obtained relatively better effect that propylene selectivity was increased to 38.1%, stability was also significantly improved.The effects of temperature, space velocity and molar ratio of water/methanol on MTP were studied that based on modified 1% P/ZSM-5 zeolite. It was showed that temperature could improve the conversion of methanol. With increasing temperature, propylene selectivity had a maximum value, methane selectivity was increased significantly and the catalyst coking was further accelerated at high temperatures, the stability of the catalyst was decreased under too low and too high temperature. Lower and higher space velocity of raw materials could reduced the yield of propylene in the product and the methanol conversion. The effect of increasing the proportion of water in raw materials was not obvious to propylene selectivity. But water would remove the reaction heat, delay the carbon deposition rate of the catalyst, prolong the lifespan of the catalyst. Finally, taking into considerations of all factors, the optimal process conditions were obtained at 450℃, LHSV of 1h-1, molar ratio of water/methanol of 1:4.