Ru改性的Fe基钙钛矿化合物的制备及结构表征

Preparation and characterization of iron-based perovskite compound with Ru modified

为了研发净化汽车尾气的新型三效催化剂,用溶胶-凝胶法分别制备了x、y值不同的LaFeO3、La1-xCexFeO3(x=0 1-0 5)、La1-xCexFe1-yCoyO3(x,y=0 1-0 5)和La1-xCexFe1-y-nCoyRunO3(x,y=0 1-0 5;n=0 01-0 1)系列化合物,制备条件为:溶液前驱液pH=7,样品在750℃恒温焙烧3h.用TG-DTA分析了晶相转化过程,XRD研究了其晶体结构,结果表明:在取值范围内均可形成具有ABO3结构的复合氧化物,钙钛矿晶相生成温度在550～650℃.Ru掺入后没改变钙钛矿型的立方晶体结构,但特征峰的2θ值减小,晶胞参数变大;随着焙烧温度的提高,特征衍射峰越来越尖锐,粒径逐渐增大,比表面积逐渐缩小,催化活性降低.IR分析表明,不同比例的Ru掺杂后所对应的红外特征峰的峰位和峰形基本相似,但随着Ru掺杂量的增加,600cm-1附近的谱带整体趋势是向高波数方向移动,但峰位并不随掺杂量的增加而成比例的移动,而是n=0 04时明显蓝移,n>0 04则没有明显移动.BET测定结果表明,在取值范围内,比表面积均为纳米级,且随焙烧温度的升高,粒径逐渐增大.

A series of LaFeO3, La1-xCex FeO3 (x = 0.1-0.5), La1-xCexFe1-y CoyO3 (x, y = 0.1-0.5) and Ru modified La1-xCexFe1-yCoyO, are prepared by sol-gel method. The formation of the perovskite structure has been characterized by X-ray diffraction (XRD) for all samples. The phase transition is determined by DTA-TG. XRD analysis reveals that the samples are pure perovskite phase, and catalyst structure keeps long else 2θ decreasing, lattice parameters enhancing arid catalysis activity increasing with Ru introduced. The specific peaks of compounds are getting stronger during temperature increasing, and the particle size grows faster. IR analysis shows that the position and shape of adsorption peaks are almost the same of all compounds, but with Ru content increasing, 600 cm-1 peak stretches to high frequency. The wavelength moves to low frequency when n=0.04, yet it doesn't vary obviously when n>0.04. The surface area (SA) values testifies that particle sizes of all catalysts are nanometer, and it increases with temperature increasing.