STUDY OF THERMAL CO-DECOMPOSITION OF MANGANESE
AND CERIUM OXALATES IN AIR AND IN INERT MEDIA
作者:O. A. Bulavchenko、Z. S. Vinokurov、O. A. Nikolaeva、T. N. Afonasenko、S. V. Tsybulya
DOI:10.1134/s0022476621030148
日期:2021.3
stages of salt decomposition. However, the addition of the second cation affects the decomposition product: as the manganese content increases, the size of CeO2 particles decreases and simple manganese oxides Mn3O4 and MnO are formed in air and in the inert atmosphere, respectively. The catalytic properties in the oxidation of CO, Mn and Ce oxidesobtained by the decomposition of oxalates in an inert
摘要 草酸盐的受控热分解是制备高度分散材料的一种有前途的方法。在这项工作中,根据阳离子比例和工艺气体气氛(空气和惰性气体)的变化,研究了锰盐和铈盐的共分解。为了这个目的,通过从硝酸盐的水溶液中共沉淀制备一系列的草酸锰和草酸锰,其中锰:铈的比例在0∶1至1∶0之间变化。通过X射线粉末衍射和扫描电子显微镜显示,铈Ce(C 2 O 4)3 ·10H 2 O和锰MnC 2 O 4 ·2H 2生成草酸酯。同样,增加锰含量会增加相应盐的含量,并影响颗粒的形貌。通过热分析,原位X射线衍射和质谱等多种物理化学方法表明,草酸盐的分解过程分为两个阶段,并取决于阳离子比率和分解气氛。第一阶段是减肥,伴随着去除结构性水分;第二阶段是减肥。该过程在惰性气体流中被加速。第二阶段是由无水盐与CO 2或CO / CO 2一起形成氧化物释放。由于放热氧化反应,分解在空气中的温度低于惰性气体中的温度。锰的引入不会显着影响盐分
Porous lanthanide oxides via a precursor method: Morphology control through competitive interaction of lanthanide cations with oxalate anions and amino acids
Porous lanthanide oxides were fabricated by a precursor-thermolysis method. The precursors were synthesized by a hydrothermal reaction with lanthanide (La, Ce, Pr and Nd) salts, sodium oxalate and asparagine (or glutamine). Under hydrothermal conditions asparagine and glutamine exhibited greatly different complexation abilities with lanthanide cations. The competitive interactions of lanthanide cations with oxalate anions and asparagine (or glutamine) gave rise to the formation of precursors with different structures and morphologies. ESI-MS detection further confirmed the different complexation abilities of asparagine or glutamine with lanthanide cations at the molecular level. Variation of oxalate anion concentration or the pH value of the reaction solution could tune the morphology of the products. After calcination, porous lanthanide oxides were obtained with the morphologies of their corresponding precursors. Our work suggests that the complexation ability of organic molecules with metal cations could be a crucial factor for morphological control of the precursors. Moreover, considering the diversity of organic additives and metal salts, other metal oxides with complex composition and morphology could be fabricated via this organic molecule-modified precursor method.
In this work, we report the synthesis and characterization of mesoporous ceria with hierarchical nanoarchitecturescontrolled by amino acids. During the synthesis procedure, cerium oxalate precipitate was treated hydrothermally with different amino acids as crystallization modifiers, and hierarchically structured cerium oxalate precursors were obtained. Ceria can be produced after thermal decomposition
Thermal decomposition of Ce-Sm and Ce-Lu mixed oxalates: Influence of the Sm- and Lu-doped ceria structure
作者:Cristina Artini、Ilaria Nelli、Marcella Pani、Giorgio Andrea Costa、Valentina Caratto、Federico Locardi
DOI:10.1016/j.tca.2017.03.013
日期:2017.5
Abstract The thermaldecomposition of the (Ce 1 − x RE x ) 2 (C 2 O 4 ) 3 * n H 2 O oxalates (RE Sm, Lu) has been studied over the whole compositional range by differential thermal analysis coupled to thermogravimetry. The temperature of the anhydrous oxalate → oxide transition results to be driven by two main factors, namely the mean cationic radius of the oxalate, which affects the RE O distances
摘要 已经通过差热分析结合热重分析在整个组成范围内研究了 (Ce 1 - x RE x ) 2 (C 2 O 4 ) 3 * n H 2 O 草酸盐 (RE Sm, Lu) 的热分解。无水草酸盐→氧化物转变的温度受两个主要因素驱动,即影响RE O距离的草酸盐的平均阳离子半径和所得氧化物的晶体结构;然后通过考虑两种化合物的晶体特性来讨论分解过程。在Ce-Sm体系中,在对应于萤石结构上限的组成处,氧化物形成温度与Sm含量的趋势出现斜率变化。在 Ce-Lu 系统中,x 范围在 0.4 和 0 之间的样品的草酸盐分解。
Nanocrystalline Oxalate/Carbonate Precursors of Ce and Zr and Their Decompositions to CeO<sub>2</sub>and ZrO<sub>2</sub>Nanoparticles
作者:Sonalika Vaidya、Tokeer Ahmad、Suman Agarwal、Ashok K. Ganguli
DOI:10.1111/j.1551-2916.2007.01484.x
日期:2007.3
The oxalate and carbonate precursors of cerium and zirconium have been prepared using reverse micelles as nanoreactors. Cerium oxalate precursor on thermal decomposition leads to a mixture of nanorods and nanoparticles of cerium oxide (nano-particles of 10 nm and nanorods with 7 nm diameter and 30 nm length). Cerium oxide with crystallite size of 10 nm was obtained from cerium carbonate precursor.