制备工艺对NiFe_2O_4分解CO_2活性的影响

Effect of NiFe_2O_4 Processing Technology on Decomposition of CO_2

随着大气中CO2浓度的增加．温室效应日趋严重．促使人们对大气中CO2的转化与消除这一课题更加重视。1990年Yutaka Tamaura发现氧缺位磁铁矿几乎可以100％分解CO2后．为解决温室效应提供了一条新的探索途径。通过对不同铁酸盐MFe2O4（M=Fe，Mn，Co，Zn，Ni等）分解CO2活性的考察．发现铁酸镍在300℃分解CO2的活性比其它铁酸盐都好。NiFe2O4的制备最常采用的是共沉淀法、柠檬酸溶胶凝胶法和水热法．3种方法由于制备工艺的不同．所制样品在微观结构上存在一定的差异。文献有关共沉淀、溶胶凝胶法用以及水热法制备铁酸镍有一定的研究．但是比较3种不同制备工艺对NiFe2O4微观结构的影响，进而研究其对分解CO2性能影响的未见报道。本文主要目的是采用XRD、H2-TPR、N2吸附．脱附等手段以及CO2分解活性测试．考察由3种制备工艺（共沉淀法、柠檬酸溶胶凝胶法和水热法）得到的纳米铁酸镍在微观性质上的差异及其对分解CO2性能的影响。

Ultra-fine NiFe2O4 particles were prepared by co-precipitation, citrates sol-gel and hydrothermal methods, respectively. The relationships between decomposition of CO2 and microstructure of NiFe2O4 were studied by means of XRD, HE-TPR and low temperature N2 sorption isotherms. The crystallite size and the pore structure of samples were different with different synthesis methods. Although all samples were nano crystals with single spinel NiFe2O4 structure, their HE-reduction processes were different. NiFe2O4 prepared by co-precipitation methods had the smallest average crystallite size and the largest BET surface areas and showed the best decomposition activity, while NiFe2O4 prepared by hydrothermal method had the biggest average crystallite size and the smallest BET surface areas and the worst decomposition activity. The phases content, crystallite size and the performance on decomposing CO2 were different for different NiFe2O4 according to the results of XRD Rietveld analysis.