摘要
用穆斯堡尔法对乙苯脱氢铁系催化剂在反应条件下进行了研究。结果表明,反应前催化剂中的铁主要以α-Fe_2O_3和α-FeOOH的形式存在,在反应中主要组分为Fe_3O_4。用K_2CO_3和α-Fe_2O_3在高温下加热可以生成KFeO_2,后者在室温下很不稳定,在同样条件下很容易转化为Fe_3O_4。但钾的存在可促进催化剂中Fe^(3+)还原为Fe^(2+),有利于电子的交换,对催化活性起着助催作用。
In-situ Mossbauer studies on iron oxide catalysts have been carried out under the reaction conditions of 873 K with 1:1 mixture of ethyl-benzene and water in a quartz cell.The GS series industrial catalysts as well as the samples prepared by calcination of the mixture of α-Fe2O3 and K2CO3 were taken as experimental samples,and the 57Fe Mossbauer spectra were recorded in transmission geometry model with a source of 40 mci 57Co(Rh).The experimental results indicate that the essential composition of iron oxide is magnetite and there is no KFeO2 crystal or amorphous solid during the reaction process.In addition,the presence of opportune amount of potassium as an indispensable promoter in the catalysts is in favour of the valence transformation from Fe3+ to Fe2+ and the formation of active center of iron catalysts for the dehydrogena-tion of ethylbenzene.
关键词
铁系催化剂
乙苯
脱氢
穆斯堡尔谱
Iron catalyst
ethylbenzene
dehydrogenatoin
Mossbauer spectroscopy
