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Journal ArticleDOI

Kinetics of thermal decomposition of copper basic carbonate

01 Mar 1977-Thermochimica Acta (Elsevier)-Vol. 18, Iss: 3, pp 310-314

About: This article is published in Thermochimica Acta.The article was published on 1977-03-01. It has received 9 citation(s) till now. The article focuses on the topic(s): Thermal decomposition & Carbonate.
Topics: Thermal decomposition (69%), Carbonate (62%), Copper (58%), Kinetics (51%)
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Journal ArticleDOI
Yuta Aoki1, Yui Yamamoto1, Nobuyoshi Koga1Institutions (1)
Abstract: The thermal decomposition of spherically granulated malachite particles was investigated to unveil the specific kinetic features of the reaction in samples in granular form toward the improvement of the thermal processing of malachite as a precursor of functional CuO. Granular malachite underwent thermal decomposition via a partially overlapping two-step mass loss process upon heating the sample in a stream of dry N2 gas. Morphologically, the process was characterized by swelling of the granular particles and cleavage divisions of the surface layer. The kinetics of the thermal decomposition was investigated through step-by-step kinetic analyses of the systematically recorded thermoanalytical curves. Finally, the kinetics of the component reaction steps was separately characterized by performing a kinetic deconvolution analysis. The first reaction step, which contributed approximately 25% to the overall reaction and followed pseudo-first-order kinetics, was attributed to the thermal decomposition of the granular particle surface. The as-produced surface product layer impeded the diffusional removal of the gaseous products, i.e., CO2 and water vapor, from the interior of the granular particles, which caused swelling of the granular particles owing to an increase in the internal gaseous pressure and the cleavage division of the surface product layer by crack formation. The second mass loss step occurred inside the granular particles under significant variations in the self-generated reaction conditions and geometrical constraints and reached its maximum rate midway through the reaction. Possible causes of the observed specific rate behavior are discussed from the viewpoint of physico-geometrical kinetics in the solid–gas system.

Journal ArticleDOI
Zhao Baolin1, Li Longfei1, Zhang Kaihua1, Kun Yu1  +1 moreInstitutions (1)
Abstract: The spectral emissivity of basic copper carbonate (Cu2(OH)2CO3) was measured by a Fourier Transform Infrared (FTIR) spectrometer in the wavelength range of 5–20 μm during the heating process, and the integral emissivity was calculated to study the effect of decomposition on emissivity. The surface composition of the samples was investigated by X-ray diffraction. Based on the spectral emissivity data and the measurement of X-ray diffraction, it can be concluded that Cu2(OH)2CO3 starts breaking down at 513 K and exists a critical state at 453–493 K. This state would cause a drop in spectral emissivity value, and enhance the oscillation intensity of spectral emissivity in 5–8 μm and spectral absorption at 14.95 μm. Above 513 K, heating time and temperature have great influences on emissivity. The emissivity changes more obvious as the increasing temperature. The emissivity of Cu2(OH)2CO3 gradually tends to be stable with heating time when the decomposition process is completed.

3 citations

Journal ArticleDOI
Zhe Ding1, Wayde N. Martens1, Ray L. Frost1Institutions (1)

21 citations

Journal ArticleDOI
Zhe Ding1, Ray L. Frost1, Jacob Kloprogge1Institutions (1)
Abstract: Much interest focuses on the use of nano-scale copper and copper oxide for catalyst use. These nano-scale chemicals are produced through the thermal decomposition of copper salts such as copper carbonate, copper hydroxy-carbonate either synthetic or natural. This paper presents some of the studies undertaken of copper carbonates.

15 citations

Journal ArticleDOI
Abstract: This article describes the design and operation of a new thermal analysis instrument which uses microwaves to simultaneously heat and detect thermally induced transformations in samples with masses in the range of 50 mg to 0.5 g. The data acquisition and control software developed for the instrument support a range of experimental techniques including constant power, linearly ramped power, linearly ramped temperature, and various modulated methods. Microwave thermal analysis utilizes the fact that physical or chemical alterations in a material, caused by processes such as melting, decomposition, or solid-solid phase changes, cause variations in its dielectric properties. These can be revealed by a variety of means including changes in the sample temperature, the differential temperature, or the shape of the power profile during linear heating experiments. The scope of the instrument is demonstrated with the decomposition of basic copper carbonate. The large temperature increase (∼100 °C) observed on the formation of the strongly coupling oxide indicates the potential sensitivity of using the thermal effects of dielectric changes as a means of detection. Further fine detail can be revealed by the use of derivative plots of either the applied power or the temperature.

19 citations

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B.M. Borham1, F. A. Olson1Institutions (1)
Abstract: The kinetics of isothermal decomposition of urea nitrate, an organic secondary explosive with monoclinic structure and chemical formula CO(NH 2 ) 2 · HNO 3 , which melts with decomposition at 152°C, was studied in open air in the temperature range 106-150°C, using a gravimetric method. Gas chromatographic analysis of product gases indicate CO 2 , N 2 O and traces of water vapor as product gases. A pasty amorphous product on the basis of wet chemical and infrared analysis was found to be cyanourea. The weight loss-time curve exhibited an acceleratory region extending almost to the end of the main reaction (35% decomposition) and followed a three-dimensional nucleation model obeying the relation x 1/3 = K(t—t 0 where α = fraction of sample reacted at time t , K = reaction rate constant, and t 0 = induction time. On the basis of this model, an enthalpy of activation of 27.6 ± 1.2 kcal/mole was calculated at 95% confidence range. The rate of decomposition was slightly accelerated in He atmosphere and slightly retarded in N 2 O and CO 2 atmospheres, while water vapor drastically reduced the rate. The reaction 3CO(NH 2 ) 2 · HNO 3 → CNNHCONH 2 (cyanourea) + 6H 2 O+3N 2 O+CO 2 is presented as the most likely one for decomposition of urea nitrate in open air.

8 citations

Journal ArticleDOI

297 citations

Journal ArticleDOI
Abstract: The thermal dehydration and deamination of some ethylenediamine complexes of Zn, Cd, Cu, Ni and Co oxalate were studied by TGA, DTA, DSC, reflectance spectroscopy, and by GE. The tris(amine) complexes deaminated to mono(amine) compounds which then decomposed directly to the metal oxide. The kinetics and heats of dehydration and deamination of several of the complexes were determined.

24 citations

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