Studies on the Non-Isothermal Decomposition of H3PMo12O40·xH2O and H4PVMo11O40·yH2O
作者： V. Sasca , M. Ştefãnescu , A. Popa
关键词: Hydrate 、 Crystal 、 Thermal analysis 、 Thermodynamics 、 Chemistry 、 Vanadium 、 Mineralogy 、 Differential thermal analysis 、 Isothermal process 、 Decomposition 、 Anhydrous
摘要: This paper reports a comparative study of the non-isothermal decompositions heteropolyacids HPM and HPVM, with structures consisting Keggin units (KUs). Non-isothermal analysis at low heating rates demonstrated existence 4 crystal hydrate species, depending on temperature. The stability domains anhydrous forms HPVM were found to be 150–380°C, respectively. Processing TG curves obtained different by Ozawa method revealed that decomposition takes place according unitary mechanism, whilst for two mechanisms are observed. Thus, first part constitution water is lost simultaneously departure vanadium from KU as VO2+, while second higher temperatures in case HPM.
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sci-hub.se 参考文章(14)
J. F. KEGGIN, Structure of the Molecule of 12-Phosphotungstic Acid Nature. ,vol. 131, pp. 908- 909 ,(1933) , 10.1038/131908B0
B. Herzog, W. Bensch, Th. Ilkenhans, R. Schl�gl, N. Deutsch, Single crystal and powder diffraction studies of the structure of heteropolymolybdophosphoric acid catalysts Catalysis Letters. ,vol. 20, pp. 203- 219 ,(1993) , 10.1007/BF00769293
C. Popescu, E. Segal, C. Oprea, A comparison of some integral methods Journal of Thermal Analysis and Calorimetry. ,vol. 38, pp. 929- 933 ,(1992) , 10.1007/BF01979425
George A. Tsigdinos, Calvin J. Hallada, Molybdovanadophosphoric acids and their salts. I. Investigation of methods of preparation and characterization Inorganic Chemistry. ,vol. 7, pp. 437- 441 ,(1968) , 10.1021/IC50061A009
Howard T. Evans, Michael T. Popev, Reinterpretation of five recent crystal structures of heteropoly and isopoly complexes: divanadodecamolybdophosphate, trivanadoenneamolybdophosphate, ".gamma.-dodecatungstophosphate", the dodecamolybdate-dodecamolybdomolybdate blue complex, and dihydrogen decavanadate Inorganic Chemistry. ,vol. 23, pp. 501- 504 ,(1984) , 10.1021/IC00172A024
V. S. Sergienko, M. A. Porai-Koshits, E. N. Yurchenko, Crystal structure and role of the water molecules in mixed vanadomolybdophosphate heteropolycompounds of the 12 series. I. A new “pseudo-Keggin” type of structure in heteropolyacids H3+n[PMo12−nVnO40]·mH2O (n=2, 3; m=30–36) Journal of Structural Chemistry. ,vol. 21, pp. 87- 99 ,(1980) , 10.1007/BF00754174
Linda C. Jozefowicz, Hellmut G. Karge, Evgenya Vasilyeva, John B. Moffat, A microcalorimetric investigation of heteropolyacids Microporous Materials. ,vol. 1, pp. 313- 322 ,(1993) , 10.1016/0927-6513(93)80047-X
G. B. McGarvey, J. B. Moffat, The interaction of alkaline earth cations with metal-oxygen cluster compounds and the implications for their use as heterogeneous catalysts Catalysis Letters. ,vol. 16, pp. 173- 180 ,(1992) , 10.1007/BF00764368
JB Black, NJ Clayden, PL Gai, JD Scott, EM Serwicka, JB Goodenough, Acrolein oxidation over 12-molybdophosphates I. Characterization of the catalyst Journal of Catalysis. ,vol. 106, pp. 1- 15 ,(1987) , 10.1016/0021-9517(87)90205-3
G. M. Brown, M. R. Noe-Spirlet, W. R. Busing, H. A. Levy, Dodecatungstophosphoric acid hexahydrate, (H5O2+)3(PW12O403−). The true structure of Keggin's `pentahydrate' from single-crystal X-ray and neutron diffraction data Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. ,vol. 33, pp. 1038- 1046 ,(1977) , 10.1107/S0567740877005330