Study of thermal decomposition of ammonium cerium sulphate

Abstract

Thermal decomposition of ammonium cerium sulphate has been studied by differential scanning calorimetry and thermogravimetry. The results show that the material decomposes in five steps in the temperature region 364-1116 K in oxygen. Based on the thermal data, elemental analysis and magnetic susceptibility measurements, sequence of decomposition has been established. The final product has been identified as CeO2 by X-ray diffractometry. Ammonium cerium sulphate and the products of the first and the final transitions contain cerium ion in 4+ oxidation state, while the three intermediate phases have cerium ion in 3+ oxidation state. From the non:isothermal DSC studies, kinetic parameters have been computed. The isothermal data show that the dehydration process follows Ginstling-Brounshtein mechanism, while the next three steps are governed by Mampel's unimolecular law of random nucleation.

Thermally induced changes in the oxidation state of cerium(IV)

“…CszCeC16 __> Cs2CeCI5 +0.5C12 (2) At about 600~ instead of Cs2CeCI5, a new phase occurred, that was expected to be Cs3CeCI 6, but its XRD pattern was completely different from those published earlier (JCPDS card No. 381315 or 381316).…”

“…Thermal decomposition of cerium(IV) salts, prepared from strong mineral acids, is in many cases accompanied by a double change in the oxidation state of cerium Ce(IV) ---> Ce(III) ---> Ce(IV) [1][2][3][4][5][6][7]. In our previous study, the effects of complexing anions and counter cations were investigated using four sulfato and nitrato complexes of Ce(IV) as samples [5].…”

Selective Catalytic Oxidation of Lean-H2S Gas Stream to Elemental Sulfur at Lower Temperature

“…The segregation of the CeO 2 crystallite may be due to the high SO 2 formation observed on the support in the absence of the active phase; in fact, among the catalysts, the highest value of SO 2 selectivity (~10%) was obtained for the CeO 2 at 327 • C as previously reported in Figure 2. The reaction temperature could favor the formation of sulfate species and also the oxygen in the ceria lattice could facilitate the CeO 2 sulfuration [33]; therefore, the reaction between CeO 2 and SO 2 could occur, leading to the formation of cerium sulfate Ce(SO 4 ) 2 , which is stable at high temperature and decomposes between 722 and 843 • C to CeO 2 [34].…”

Titrimetric Analysis of Some Antituberculous Drugs Using Ammonium Hexanitratocerate(IV) Reagent

“…A variety of compounds containing cerium(IV) have proved to be versatile reagents capable of oxidizing almost every oxidizable functional group 1 . Extensive work has lead to the development of a good number of such oxidants like cerium mischmetal 2 , cerium ammonium sulphate 3,4 , cerium sulphate 5,6 , cerium nitrate 7 , cerium fluoride 8 , cerium chloride 9,10 , cerium oxide 11,12 , cerium metal 13 , cerium carbonate 14 and cerium acetate 15 . There is no general method reported in Indian Pharmacopoeia 16 for the estimation of all antituberculous drugs.…”

“…Industrial demands have led many workers to search for more ideal oxidants with a number of specifications including: lower cost, higher yields, better selectivity, milder neutral conditions, easier preparations, high solubility, less toxicity and short reaction times. Among the above mentioned reagents [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] , ammonium hexanitratocerate(IV) has an edge over others for rendering easy manipulation and sharp end points. Therefore we have selected ammonium hexanitratocerate (AHC) as an oxidizing reagent for our study.…”