铁锰复合氧化物的氧化还原沉淀法制备及其表征

Characterization of Iron\|Manganese Mixed Oxides Prepared by Oxydoreduction Precipitation Method

分别采用氧化还原沉淀法和常规共沉淀法制备得到铁锰复合氧化物， 并对样品进行了 Ｘ射线衍射、 Ｂ Ｅ Ｔ比表面积、程序升温还原的初步表征和比较． 结果表明， 与常规共沉淀法制备的样品相比较， 采用氧化还原沉淀法制备的铁锰复合氧化物具有粒径较小、较大的比表面积、铁锰互溶性好、铁锰物种之间的相互作用较强等特点． 作为一种较为新颖的催化剂制备方法， 氧化还原沉淀法利用在高低价可变金属离子之间发生氧化还原反应的同时使之沉淀， 不利于各相单独形成微晶， 有利于不同金属离子的均匀混合． 此种方法对制备高比表面积、含变价过渡金属离子的各类复合氧化物催化剂有其独到之处．

Iron\|manganese mixed oxides were prepared by oxydoreduction precipitation method and conventional coprecipitation method, and characterized using X\|ray powder diffraction, BET surface area measurement and TPR methods. The results revealed that compared to the samples prepared by conventional coprecipitation, the iron\|manganese mixed oxides prepared by oxydoreduction precipitation have smaller crystallite sizes, larger surface areas and stronger interaction between iron and manganese species. As a novel method for preparation of catalytic materials, oxydoreduction precipitation method, in which the oxydoreduction reaction and precipitation are carried out at the same time, is unfavorable to the formation of micro\|crystals from each single component, but beneficial to the formation of uniform solid solution of different components. This method is unique for the preparation of mixed oxide catalysts with high surface areas containing metals of variable valences.