A-site deficient lanthanum-calcium chromite-titanates doped with 3d transition metals: synthesis, oxygen nonstoichiometry, electrical conductivity, and catalytic activity
A-site deficient lanthanum-calcium chromite-titanates doped with 3d transition metals: synthesis, oxygen nonstoichiometry, electrical conductivity, and catalytic activity
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DOI：
10.1007/s11581-007-0083-1
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发表时间：
2007-06
期刊：
影响因子：
2.8
通讯作者：
V. Vashook;R. Müller;J. Zosel;K. Ahlborn;F. Gerlach;P. Tietz;G. Stöver;U. Guth
中科院分区：
文献类型：
--
作者：
V. Vashook;R. Müller;J. Zosel;K. Ahlborn;F. Gerlach;P. Tietz;G. Stöver;U. Guth
采用常规固相反应法制备了6种（M = Cr，Mn，Fe，Co，Ni，Cu）和2种（M = Ni，Cu）单相合金。在较宽的温度和氧分压范围内，考察了这些化合物的氧非化学计量比、电导率、高温还原-再氧化相变和烃类氧化催化活性。含Cu、Ni、Co和Fe的组合物在1，000 °C下在pH 2 O/pH 2 = 0.3的还原性Ar/H2O/H2气氛中分解，而含Cr和Mn的陶瓷在相同条件下保持稳定。在含Cu和Ni的组合物的情况下，通过X射线衍射法记录分解后形成的添加的3d元素的金属颗粒。这些形成的复合材料可以通过在1,000 °C的空气中处理而完全再氧化，形成初始组合物。在空气和Ar/H_2O/H_2气流中，随着M含量的增加，陶瓷的电导率增加。对CH 4和C3 H6的催化氧化活性最高，与复合物的活性相当，表明含Cu的粉末。
Six(M = Cr, Mn, Fe, Co, Ni, Cu) and two(M = Ni, Cu) single-phase compositions were prepared by conventional solid-state reactions. Oxygen nonstoichiometry, electrical conductivity, phase transformations under reduction-reoxidation at high temperatures and catalytic activity for hydrocarbons oxidation of these compositions were investigated in a wide temperature and oxygen partial pressure range. The Cu-, Ni-, Co-, and Fe-containing compositions are decomposed in reducing Ar/H2O/H2atmosphere with pH2O / pH2= 0.3 at 1,000 °C, while the Cr- and Mn-containing ceramics remain stable at the same conditions. The metallic particles of the added 3d elements formed after decomposition were registered by X-ray diffraction method in case of Cu- and Ni-containing compositions. These formed composites can be completely reoxidized with formation of initial compositions by treatment in air at 1,000 °C. The electrical conductivity of the ceramics investigated in air and Ar/H2O/H2gas flow increases with rising M content. The highest catalytic activity for oxidation of CH4and C3H6, which was comparable with the activity of thecomposite, shows the Cu-containing powders.