Topic
Chemical decomposition
About: Chemical decomposition is a research topic. Over the lifetime, 5210 publications have been published within this topic receiving 127503 citations. The topic is also known as: analysis reaction & chemical decomposition reaction.
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01 Jan 2011
TL;DR: In this article, a novel energetic material, 4,5-dihydroxyl-2- (dinitromethylene)-imidazolidine (DDNI), was synthesized by the reaction of FOX-7 and glyoxal in water at 70 C. Thermal behavior of DDNI was studied with DSC and TG-DTG methods, and presents only an intense exothermic decomposition process.
Abstract: A novel energetic material, 4,5-dihydroxyl-2- (dinitromethylene)-imidazolidine (DDNI), was synthesized by the reaction of FOX-7 and glyoxal in water at 70 C. Thermal behavior of DDNI was studied with DSC and TG- DTG methods, and presents only an intense exothermic decomposition process. The apparent activation energy and pre-exponential factor of the decomposition reaction were 286.0 kJ mol -1 and 10 31.16 s -1 , respectively. The critical temperature of thermal explosion of DDNI is 183.78 C. Specific heat capacity of DDNI was studied with micro- DSC method and theoretical calculation method, and the molar heat capacity is 217.76 J mol -1 K -1 at 298.15 K. The adiabatic time-to-explosion was also calculated to be a certain value between 14.54 and 16.34 s. DDNI presents lower thermal stability, for its two ortho-hydroxyl groups, and its thermal decomposition process becomes quite
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TL;DR: In this article, the first order decomposition of 9-diazofluorene by copper(II) tetrafluoroborate in acetonitrile solvent has been investigated.
Abstract: The kinetics and products of the decompositon of 9-diazofluorene by copper(II) tetrafluoroborate in acetonitrile solvent have been investigated. The reaction is first order with respect to both 9-diazofluorene and copper(II) tetrafluoroborate. A reaction mechanism has also been proposed.
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TL;DR: In this paper, the authors investigated the thermal decomposition of pristine and γ-irradiated zinc uranyl acetate (ZnU3O10) in air using isothermal and dynamic thermogravimetric techniques.
Abstract: Thermal decomposition of pristine and γ-irradiated zinc uranyl acetate was investigated in air using isothermal and dynamic thermogravimetric techniques. The decomposition proceeded via one major process with the formation of triuranates ZnU3O10 as solid residues. Kinetic analysis of isothermal data, when compared with various solid-state reaction models, showed that the decomposition reaction is best fitted by the phase-boundary model. Kinetic analysis of the dynamic TG curves was discussed with reference to integral methods of modified Coats and Redfern equations. Kinetic and thermodynamic parameters were calculated and evaluated. IR spectroscopy and X-ray powder diffraction techniques were employed to follow the chemical composition of solid residue at different calcination temperatures. The results display that the triuranate ZnU3O10 starts forming by calcination of zinc uranyl acetate at temperatures > 300 °C and undergoes decomposition at higher temperatures (>600 °C) with the formation of U3O8. The...
01 Jan 2001
TL;DR: In this article, the catalytic properties of LaCoO3 in aqueous oxidation are explored as a function of doping, both Sr substitution for La and Fe/Ni substitution for Co are studied.
Abstract: The catalytic properties of LaCoO3 in aqueous oxidation are explored as a func- tion of doping. Both Sr substitution for La and Fe/Ni substitution for Co are studied. The re- action of interest is the aqueous epoxidation of crotyl alcohol with hydrogen peroxide. The reaction products are measured using GC, and the decomposition of hydrogen peroxide is studied using the volume of oxygen evolved during reaction. Strong variations in the activ- ity to epoxide formation are observed, with Fe-doped samples being rather inactive in the reaction. SR VUV photoemission is used to explore the surface reactivity of the ceramic catalysts in aqueous solution, using H2O as a p robe molecule. These measurements are complemented by XANES measurements designed to probe the local defect structure and XPS measurements of surface composition. We relate the observed catalytic activity to the defect structure of the doped materials. In Ni-doped materials, oxygen vacancies appear to be the predominant defect, whereas in Fe-doped samples, electron holes are stabilized on Fe, leading to very different catalytic behaviour. Surface studies in combination with AA measurements reveal some dissolution of the catalyst into solution during the reaction. The surface reactivity to water is influenced by the TM d electron count, with water binding more strongly to Fe-doped materials than to those containing Ni. The influence of these fac- tors on the rate of the unwanted hydrogen peroxide decomposition reaction and hence on ac- tivity in epoxidation is discussed.
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TL;DR: In this paper, the high-Tc superconducting oxide Yba2Cu3O7-y has been prepared by the amorphous citrate process, and the precursor was fired to high temperature to form the desired compound.
Abstract: The high-Tc superconducting oxide Yba2Cu3O7–y has been prepared by the amorphous citrate process. A citrate-nitrate solution was prepared at room temperature and dehydrated at around 80°C to yield a solid precursor material. The precursor was fired to high temperature to form the desired compound. The decomposition mechanism was studied with thermogravimetric analysis and X-ray diffraction. Intermediate products were formed during the decomposition reactions. Nearly phase-pure Yba2Cu3O7-y powders were obtained by firing the precursor in air to 900°Cfor2 h. Sintered samples were typically over 90% dense and exhibited good superconducting properties.