助剂对F－T合成Fe－Mn共沉淀催化剂的影响　Ⅲ．催化剂的MES表征

Effect of promoters on tile co-precipitated Fe/Mn catalyst for FT synthesis III.MES analysis of the cstalysts

用穆斯堡尔谱（ＭＥＳ），考察了助剂Ｌａ、Ｋ、Ｖ、Ｚｎ对共沉淀Ｆｅ－Ｍｎ催化剂经焙烧、还原及Ｆ－Ｔ合成反应等不同过程后体相结构的影响。研究表明．４５０℃焙烧后，Ｆｅ－Ｍｎ催化剂由铁磁性和超顺磁性α－（Ｆｅ１－ｘＭｎｘ）２Ｏ３组成。助剂Ｌａ、Ｋ、Ｖ、Ｚｎ的加入均可使催化剂晶粒细化，其中尤以Ｌａ作用最强；还原后，Ｆｅ－Ｍｎ本底催化剂包含超顺磁α－（Ｆｅ１－ｘＭｎｘ）２Ｏ３、（Ｆｅ１－ｚＭｎｚ）Ｏ及α－Ｆｅ等物相，上述助剂的加入均可使α－Ｆｅ的量减少；同时助剂Ｖ、Ｚｎ还使催化剂中出现（Ｆｅ１－ｙＭｎｙ）３Ｏ４尖晶石新相；ＦＴ合成反应后，本底催化剂由超顺磁α（Ｆｅ１－Ｍｎｘ）２Ｏ３、（Ｆｅ１－ｚＭｎｚ）Ｏ、ｘ－Ｆｅ５Ｃ２、ε－Ｆｅ２．２Ｃ及（Ｆｅ１－ｙＭｎｙ）３Ｏ４等物相组成，助剂Ｌａ、Ｋ均使催化剂中碳化物的量增多，其中Ｌａ主要促进生成ε－Ｆｅ２．２Ｃ，而Ｋ则主要促进Ｘ－Ｆｅ５Ｃ２的生成；助剂Ｖ、Ｚｎ使碳化物的量减少，氧化物的量增多，且碳化物主要是ε－Ｆｅ２．２Ｃ。

By using Mossbauer Effect Spectroscopy(MES),the effect of promoters such as La,K,V,Zn on the phase composition of co-precipitated Fe/Mn catalyst after calcination,reduction and FT synthesis have been studied.It was found that the bulk catalyst consists of both magnetic and ultra-paramagnetic α-(Fe1-xMnx)2O3 after calcination at 450℃.The addition of La,K,V.and Zn can make the catalyst particle to be fine.especially La is the most effective one among them.After reduction, the bulk catalyst is composed of (Fe1-z.Mnz)O,α-Fe and ultra-paramagnetic α-(Fe1-xMnx )2O3.The addition of above mentioned promoters may decrease the content of α-Fe,and other two were increased in the reducedcatalyst.Simultaneously,for V and Zn the new (Fe1-y Mny)3O4 spinel phase can be formed during reduction.The MES results of bulk catalyst after FT synthesis indicated that there are (Fe1-z Mnz)O,x-Fe5C2 ε-Fe2.2 C,(Fe1-yMny)3O4 and ultra-paramagnetic α-(Fe1-xMnx )2O3 in the reacted sample.The contents of carbides in the catalysts promoted with La and K were increased. hilt the carbide phase was mainly ε-Fe2.2C for La and x-Fe5C2 for K.The addition of V and Zn can increase the (Fe1-yMny)3O4 spinel but decrease the content of carbide with mainly ε-Fe2.2C.