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丙烷在Pt-Sn-K/Al_2O_3催化剂上脱氢反应时,为得到高的丙烯收率及催化剂有良好的脱氢稳定性,反应需要在高温临氢条件下进行。本文通过对催化剂在H_2中经不同温度处理后表面形态及催化性能的变化考察,认为Sn 和K 首先分别吸附在不同的γ-Al_2O_3表面区域上,只有当两者的含量高到一定程度时,才发生共吸附在同一表面区域上。此时,高温临氢条件下K 将促进氧化态锡还原为零价锡(Sn)而使催化剂中毒。但是,低Sn 载量及低温反应时,K 影响不大。这样,可以通过控制K 和Sn 的含量来调整活性和稳定性。
When the propane is dehydrogenated on the Pt-Sn-K / Al 2 O 3 catalyst, the reaction needs to be carried out under high temperature and in the presence of hydrogen in order to obtain high propylene yield and good dehydrogenation stability of the catalyst. In this paper, we investigated the surface morphologies and catalytic properties of H 2 catalysts treated by different temperatures. It is concluded that Sn and K are adsorbed on different γ-Al 2 O 3 surface areas respectively. Only when the content of both are high, Co-adsorption occurred in the same surface area. At this point, under high temperature hydrogen conditions, K will promote oxidation of tin reduction of tin (Sn) and the catalyst poisoning. However, low Sn loading and low temperature reaction, K little effect. In this way, it is possible to adjust the activity and the stability by controlling the contents of K and Sn.