Temperature programmed decomposition of cobalt ethylene diamine complexes

Dash, S.; Ajikumar, P.K.; Kamruddin, M.; Tyagi, A. K.

doi:10.1016/s0040-6031(99)00186-0

Cited by 12 publications

(8 citation statements)

References 26 publications

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“…With this complementary information, complete structural-chemical transformations occurring in the course of thermal process could be mapped out. In addition to studying the model substances to standardize and optimize the system performance (Kamruddin et al 1997), the decomposition of aluminum ammonium sulphate (alum -a double salt) (Kamruddin et al 1996), cobalt ethylene diamine complexes (Dash et al 1999a), cerium nitrate , thorium carbonate and technologically relevant materials like uranyl nitrate hexahydrate (Dash et al 1999b), thorium nitrate pentahydrate (Dash et al 2000a), thorium oxalate hexahydrate , which are important precursors encountered in the back end of the nuclear fuel reprocessing, are also studied. In most of the above substances the TPD results in the formation of nanocrystalline products.…”

Section: Resultsmentioning

confidence: 99%

Thermogravimetry-evolved gas analysis-mass spectrometry system for materials research

et al. 2003

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Abstract. Thermal analysis is a widely used analytical technique for materials research. However, thermal analysis with simultaneous evolved gas analysis describes the thermal event more precisely and completely. Among various gas analytical techniques, mass spectrometry has many advantages. Hence, an ultra high vacuum (UHV) compatible mass spectrometry based evolved gas analysis (EGA-MS) system has been developed. This system consists of a measurement chamber housing a mass spectrometer, spinning rotor gauge and vacuum gauges coupled to a high vacuum, high temperature reaction chamber. A commercial thermogravimetric analyser (TGA: TG + DTA) is interfaced to it. Additional mass flow based gas/vapour delivery system and calibration gas inlets have been added to make it a versatile TGA-EGA-MS facility. This system which gives complete information on weight change, heat change, nature and content of evolved gases is being used for (i) temperature programmed decomposition (TPD), (ii) synthesis of nanocrystalline materials, (iii) gas-solid interactions and (iv) analysis of gas mixtures. The TPD of various inorganic oxyanion solids are studied and reaction intermediates/products are analysed off-line. The dynamic operating conditions are found to yield nanocrystalline products in many cases. This paper essentially describes design features involved in coupling the existing EGA-MS system to TGA, associated fluid handling systems, the system calibration procedures and results on temperature programmed decomposition. In addition, synthesis of a few nanocrystalline oxides by vacuum thermal decomposition, gas analysis and potential use of this facility as controlled atmosphere exposure facility for studying gas-solid interactions are also described.

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Section: Resultsmentioning

confidence: 99%

Thermogravimetry-evolved gas analysis-mass spectrometry system for materials research

et al. 2003

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“…1). The process of the adsorption of water molecules by complexes of this type is probably their distinctive feature [18].…”

Section: Thermal Analysismentioning

confidence: 99%

Thermal properties of [Co(en)2Cl2]Cl in solid state. Cis–trans isomerization of the [Co(en)2Cl2]+ complex ion in methanol

Jacewicz

Pranczk

Wyrzykowski

et al. 2014

Reac Kinet Mech Cat

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]Cl complex isomers have been studied using the TG-FTIR and TG-DSC-MS techniques. The measurements were carried out in argon atmosphere over the temperature range 293-873 K. The influence of the configurational geometry on the pathways of thermal transformations was discussed. Furthermore, kinetic studies on the reaction of the cis-trans isomerization of the [Co(en) 2 Cl 2 ]Cl complex salt in methanolic solutions were performed using UV-Vis spectrophotometry at five temperatures in the 293-313 K temperature range. The observed rate constants were computed using the ''Glint'' program based on the global analysis. It has been found that the cis-trans isomerization of [Co(en) 2 Cl 2 ]Cl is a first order reaction. Furthermore, the cis/trans [Co(en) 2 Cl 2 ]Cl isomerization proceeds according to the dissociative mechanism.

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“…Nine separate crystalline phases are identifiable from these data which were either identified by comparison with reference patterns from the ICSD or else, where no reference patterns exist (i.e., for the (en)-containing phases), phase assignment is proposed based on both previous literature and comparative analysis of temperature-programmed MS desorption data (ESI). [29] Initially, from a diffraction perspective only peaks corresponding to reflections for the g-Al 2 O 3 support phase were observed at room temperature. No crystalline Ni-containing phases were observed, although UV/Vis spectroscopy reveals that Ni is present on the support as the complex Ni(en)(H 2 O) 2 (AlÀ O) 2 .…”

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Dynamic X‐Ray Diffraction Computed Tomography Reveals Real‐Time Insight into Catalyst Active Phase Evolution

et al. 2011

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Dedicated to the Fritz Haber Institute, Berlin, on the occasion of its 100th anniversary Metals and metal oxides anchored to porous support materials are widely used as heterogeneous catalysts in a number of important industrial chemical processes. These catalysts owe their activity to the formation of unique metal/metal oxide support interactions, typically resulting in highly dispersed actives stabilized in a particular electronic or coordination state. [1][2][3] They are employed in fixed-bed reactors as extruded or pelletized millimeter-sized "catalyst bodies" minimizing pressure drops along the length of the reactor. Since the efficiency of the whole catalytic system depends on the behavior and efficiency of the catalyst body per se, its design has very great importance. Crucial to this design is an understanding of the factors which influence the distribution and nature of the active phase during preparation. The type of desired distribution is very much dependant on catalytic process and required products; for example, an egg-shell distribution (as opposed to uniform, egg-white, or egg-yolk), where the active phase is located at the edges of the catalyst body, can be favored if the product forms readily. [4,5] Herein, we study catalyst bodies of nickel supported on gAl 2 O 3 . These catalysts are widely employed for hydrogenation. [1][2][3]6] They are often prepared using highly soluble nickel nitrate or chloride precursor salts, which allow for the preparation of catalysts with high metal loadings in a single impregnation step. Two problems are commonly encountered with the preparation of these catalysts: the formation of unwanted metal aluminate (spinel) phases and poor metal dispersion within the catalyst body. The dispersion of the metal ions within the alumina can be controlled by the addition of complexing agents to the impregnation solution, thereby changing the molecular structure of the precursor (through ligand exchange) as well as the interactions of the precursor with the support. Additionally, the presence of chelating ligands in the precursor increases both the metal oxide reducibility and dispersion. [7][8][9][10] In recent times, absorption, spectroscopic, and scattering techniques have been developed to obtain spatial information on the distribution of chemical species in catalyst bodies, which allows the phenomena taking place during their preparation to be monitored. [7] These techniques include Raman, IR, and UV/Vis microspectroscopy; magnetic resonance imaging (MRI); tomographic energy dispersive diffraction imaging (TEDDI); and micro-computed tomography (mCT). [11][12][13][14][15][16][17] Importantly, both MRI and TEDDI are able to probe in a non-invasive manner in two dimensions, thus providing time-resolved information on both the impregnation and calcination/activation processes. Whilst the former is limited to the study of paramagnetic species and is therefore almost exclusively limited to probing the impregnation stage, TEDDI provides detailed information regarding elemental and ...

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Temperature programmed decomposition of cobalt ethylene diamine complexes

Cited by 12 publications

References 26 publications

Thermogravimetry-evolved gas analysis-mass spectrometry system for materials research

Thermogravimetry-evolved gas analysis-mass spectrometry system for materials research

Thermal properties of [Co(en)2Cl2]Cl in solid state. Cis–trans isomerization of the [Co(en)2Cl2]+ complex ion in methanol

Dynamic X‐Ray Diffraction Computed Tomography Reveals Real‐Time Insight into Catalyst Active Phase Evolution

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