The Study About Catalystic Performance Of Modified ZSM-5in Propane Dehydrogenation

As the second most important intermediate in the petrochemical industry, propylene is mainly from the naphtha-cracking processes. But as the worldwide consumption of crude oil is getting largely, the production cost of propylene is becoming higher and higher. In order to reduce the production cost and meet the rising global propylene demand, it is desirable to find a new technique to produce proplene. Recently, using light paraffin, instead of crude oil, as feedstock to generate propylene obtains more and more attention.In this study, thermodynamic analysis of propane dehydrogenation was considered. Then, the effect of different Si/Al ratio Pt-Zn-K modification and reaction tempreture on catalystic performance in propane dehydrogenation was investigated. The main conclusions are as following:1. The thermodynamic results indicated that the process of propane dehydrogenation was a highly endothermic process. The reaction conditions with high tempreture and low pressure are good for propane dehydrogenation reaction.2. Experimental results shows that at high reaction temperatures, the catalyst with low Si/Al ratio has a better catalytic performance in propane dehydrogenation. But when temperature is too high, the catalysts deactivate easily.3. For Zn/ZSM-5zeolites in propane dehydrogenation, the propane conversion was reduced compared to untreated ZSM-5. But the selectivity and yield of propylene were increased gradually as the content of zinc increased.4. For Pt-Zn/ZSM-5and Pt-Zn-K/ZSM-5catalysts in propane dehydrogenation, the addition of Zn and K is not only good for the dispersion of Pt on the surface of zeolites, but the addition of zinc also good for dehydrogenation ability improved. Thus, for metal modified ZSM-5the stability of catalysts and selectivity of propylene were improved compared to untreated ZSM-5.