| TG-DTA-MS and Controlled-Rate TG of Ammonium Oxalate Monohydrate (NH4)2C2O4·H2O |
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† A paper presented at the 47th Annual Conference on Mass Spectrometry (May 12-14, 1999, Osaka, Japan). * Corresponding author, e-mail: t-arii@rigaku.co.jp, Tel: 042-545-8126, Fax: 042-544-9650 *a) Thermal Analysis Division, Rigaku Corporation (3-9-12 Matsubara-cho, Akishima, Tokyo 196-8666, Japan) b) Department of Applied Chemistry, Faculty of Engineering, Tokyo Institute of Polytechnics (1583 Iiyama, Atsugi-shi, Kanagawa 243-0297, Japan) c) Department of Materials Science and Ceramic Technology, Faculty of Engineering, Shonan Institute of Technology (1-1-25 Tsujido-nishikaigan, Fujisawa, Kanagawa 251-8511, Japan) d) Graduate School of Engineering, Tokyo Institute of Polytechnics (1583 Iiyama, Atsugi-shi, Kanagawa 243-0297, Japan) |
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| Ammonium oxalate monohydrate (NH4)2C2O4·H2O was investigated by TG-DTA-MS and controlled-rate TG. The decomposition process in both inert and simulated air atmospheres was successfully clarified; the gaseous products evolved with three endothermic mass losses were confirmed by the mass detection. Detection of ammonia from the dehydrate (NH4)2C2O4 supported the formation of ammonium hydrogen oxalate (NH4)HC2O4 which decomposed at the higher temperature to form ammonia, water vapor, carbon monoxide and carbon dioxide. The successive mass losses were clearly separated and characterized by controlled-rate thermogravimetry, CRTG. The well-defined mass loss curve brought by CRTG agreed excellently with the theoretical mass losses calculated based upon formation of anhydrous ammonium oxalate and ammonium hydrogen oxalate, respectively. The gaseous products detected under the thermo-oxidative decomposition were attributed to the oxidized products for those obtained under the inert atmosphere. Thermal change in the oxidation atmosphere accompanied nitrogen monoxide NO, extra formation of water vapor and carbon dioxide. The decomposition mechanism was little affected by the atmospheric differences. The decomposition mechanism of (NH4)2C2O4·H2O was proposed. | ||
| Key words: TG-DTA-MS, Controlled-rate thermogravimetry, Ammonium oxalate, Reaction mechanism | ||
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