Study Of New Catalysts For Propane And C₄ Liquefied Petroleum Gas To Propene

At present,the propene is mainly derived from ethylene steam cracking, By -product of FCC process in refinery and propane dehydrogenation. There are two catalysts for propane dehydrogenation: Pt catalyst and Cr catalyst. The price of Pt is very high, and the catalyst needs high purity of raw material; conversely, Cr catalyst do not need high purity of raw material, and the price is low. The disadvantage of Cr catalyst is rapid inactivation and frequent of regeneration.In recent years, the preparation of propylene using C₄ has become a hot research.Many companies like UOP and Philips developed their own technologies in preparation of propylene using C₄ olefin cracking, But the source of its raw materials is litter, and the yield is not high. Therefore, preparing a new catalyst for propane dehydrogenation to propylene and broadening the range of raw materials of C₄ become a problem to be solved.Due to impregnation method to prepare Cr-Al catalyst, the Cr is easy to loss and join, making the performance of the catalyst decline in regeneration process, seriously affected the yield of propylene. So, this study using Sol-gel method to prepare the catalyst, not only the active components of the catalyst prepared in this way attach to the catalyst surface, but also a large part of it embed in the catalyst, this makes the active components not easy to lose, can increase the use of chromium,we can also solved the problem of rapid catalyst deactivation.For using carbon as raw material to prepare propylene, from the literatures of inspection, most of the catalyst use ZSM-5 zeolite , but the catalyst is only for butene cracking. In order to broaden the range of raw materials, we can add Cr/Al catalyst into ZSM-5 zeolite, with the mutual cooperation by dehydrogenation ability of Cr on the alkane and good propylene capacity of Zeolite ZSM-5 to butene cracking, Successfully developed the catalyst which has a dual function both a catalytic dehydrogenation of propane can also propylene using C₄ fraction cracking , LPG can be used directly to propylene.In addition,this study examined the catalytic performance of the response of the carrier and active components, optimized the group distribution ratio and the preparation conditions of catalyst. Characterized the related catalyst with BET,XRD and so on.While investigated the stability, activity and other properties of the catalyst. Experimental results show: The catalyst prepared has good activity on the product propylene; burned the catalyst repeatedly and aginged through water vapor, proved that the stability of the catalyst is also very good. The article also examined the performance of the catalyst in different temperature, different space velocities and different pressures, obtained optimized reaction conditions. Making experiments with difference materials, demonstrate that the catalyst system has a strong adaptability to raw materials, extent the range of raw materials, and obtain a relatively high yield of propylene.