乙苯脱氢制苯乙烯Fe_2O_3-K_2O系催化剂的XPS研究

对铈、钼助催的Fe_2O_3-K_2O乙苯脱氢制苯乙烯催化剂使用前后和工业用后卸下的样品作XPS研究,结果表明:用后催化剂中铁以Fe~(2+)和e~(3+)两种价态并存,表面上生成一定量羟基,反应条件下钾和氧化铁发生作用生成新相K_2Fe_2O_4,它也是活性相,表面钾被水蒸汽溶解随物料流动而迁移流失,钾的流失是失活的重要原因,还有结构因素的影响,在催化剂表面铈以CeO_2微晶存在,反应条件下部分被还原,因而增加了晶格氧的活动性和电子传递渠道,通过促进氧转移脱氢而使催化剂脱氢活性增加。

Study on Fe_2O_3-K_2O Based Catalyst for Dehydrogenation of Ethylbenzee to Styrene by XPS

The characterization of catalysts used for dchydrogenation of ethylbenxene to styrene has been studied by XPS and other methods. These catalysts are FexO3-K2O based catalysts with Ce and Mo promoters in fresh and industrally used form. All elements, namely Fe,K,O,Ce and Mo present on the catalyst surface have been identified. The results reveals that reduction of Fe3O3 to Fe3O4. formation of hydroxyl phase of iron from steam, reaction between Fe2O3 and K2O, loss/migration of K take place during dehydrogenation reaction. Ce exists as crystalite of CeO2,it was partly reduced under the reaction condition, hence the mobility of lattic oxygen and the electron transfer has been increased, and the activity of catalyst for dehydrogenation was thus promoted through oxygen-transfer dehyrogenation mechanism. Mo exists as crystallite of K2MoO4.