15750-47-7Relevant articles and documents
STUDY OF THERMAL CO-DECOMPOSITION OF MANGANESE AND CERIUM OXALATES IN AIR AND IN INERT MEDIA
Bulavchenko,Vinokurov,Nikolaeva,Afonasenko,Tsybulya
, p. 467 - 480 (2021/04/26)
Abstract: Controlled thermal decomposition of oxalate salts is a promising method for the preparation of highly dispersed materials. In this work, co-decomposition of Mn and Ce salts is studied upon variations of the cation ratio and the gas atmosphere of the process (air and inert gas). To this aim, a series of Mn and Ce oxalates is prepared by co-precipitation from aqueous solutions of nitrates with Mn:Ce ratios varying from 0:1 to 1:0. It is shown by X-ray powder diffraction and by scanning electron microscopy that cerium Ce(C2O4)3·10H2O and manganese MnC2O4·2H2O oxalates are formed. Also, increasing manganese content increases the amount of the corresponding salts and affects the morphology of the particles. It was shown by a number of physicochemical methods such as thermal analysis, in situ X-ray diffraction, and mass spectrometry shows that the oxalate decomposition proceeds in two stages and depends on the cation ratio and the decomposition atmosphere. The first stage is a weight loss accompanied by removal of structural water; this process is accelerated in a flow of an inert gas. The second stage is the formation of oxides from the anhydrous salt accompanied by CO2 or CO/CO2 release. Due to exothermic oxidation reaction, the decomposition occurs at lower temperatures in air than in an inert gas. The introduction of manganese does not significantly affect the temperature ranges of the first and second 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 oxides obtained by the decomposition of oxalates in an inert gas and in air are studied. It is shown that the catalysts formed in the oxidizing environment are more active.
Ultrasonic-assisted solution-phase synthesis and property studies of hierarchical layer-by-layer mesoporous CeO2
Zhao, Pu Su,Gao, Xiu Mei,Zhu, Feng Xia,Hu, Xin Ming,Zhang, Li Li
, p. 375 - 380 (2018/02/13)
Hierarchical layer-by-layer quadrangle CeO2 was prepared through ultrasonic-assisted solution-phase synthesis strategy using cerium oxalate as the precursor. The as-prepared mesoporous CeO2 displayed a surface area of 98.7 m2 g?1 and pore diameters of 2.0–10.0 nm. The high-resolution TEM image revealed that the layer structures of the CeO2 were made of numerous nanocrystal particles with the crystallite size of about 13–15 nm. High energy and cavitation of ultrasonic wave assists cerium oxalate precursor in building the layer-by-layer quadrangle staking. UV–vis absorption spectrum showed that the direct allowed transition bandgap energy for the as-prepared CeO2 was 2.91 eV. Moreover, the CeO2 exhibited good photocatalytic property for degrading Rhodamine B solution under UV radiation.
Porous lanthanide oxides via a precursor method: Morphology control through competitive interaction of lanthanide cations with oxalate anions and amino acids
Shen, Zhu-Rui,Wang, Jin-Gui,Sun, Ping-Chuan,Ding, Da-Tong,Chen, Tie-Hong
, p. 6112 - 6123 (2010/08/08)
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.
