Effect of metal oxide additives on the thermal decomposition of perchlorates, oxalates and hydroxides
TL;DR: In this paper, the effects of α-Fe2O3 and α-Al 2O3 additives on the thermal decomposition of perchlorates, oxalates and hydroxides were investigated by means of DTA, TG and X-ray techniques.
About: This article is published in Thermochimica Acta.The article was published on 1977-09-01. It has received 37 citations till now. The article focuses on the topics: Thermal decomposition & Decomposition.
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TL;DR: Preliminary investigations indicate that themaximum decomposition temperature of AP is significantly reduced in the presence of CoO/Co 3O 4 composite nanocrystals and that the maximum decomposition peak shifts toward lower temperatures as the loading amount of the composite Nanocrystals increases.
Abstract: This work addresses the chemical nature of the catalytic activity of X-ray "pure" CoO nanocrystals. All samples were prepared by a solvothermal reaction route. X-ray diffraction indicates the formation of CoO in a cubic rock-salt structure, while infrared spectra and magnetic measurements demonstrate the coexistence of CoO and Co 3O 4. Therefore, X-ray "pure" CoO nanocrystals are a unique composite structure with a CoO core surrounded by an extremely thin Co 3O 4 surface layer, which is likely a consequence of the surface passivation of CoO nanocrystals from the air oxidation at room temperature. The CoO core shows a particle size of 22 or 280 nm, depending on the types of the precursors used. This composite nanostructure was initiated as a catalytic additive to promote the thermal decomposition of ammonium perchlorate (AP). Our preliminary investigations indicate that the maximum decomposition temperature of AP is significantly reduced in the presence of CoO/Co 3O 4 composite nanocrystals and that the maximum decomposition peak shifts toward lower temperatures as the loading amount of the composite nanocrystals increases. These findings are different from the literature reports when using many nanoscale oxide additives. Finally, the decomposition heat for the low-temperature decomposition stages of AP was calculated and correlated to the chemical nature of the CoO/Co 3O 4 composite nanostructures.
111 citations
TL;DR: A combination of preliminary mineralogical analyses and suitably selected pyrolysis temperatures may increase future success in the search for past or present life on Mars.
Abstract: The search for in situ organic matter on Mars involves encounters with minerals and requires an understanding of their influence on lander and rover experiments. Inorganic host materials can be helpful by aiding the preservation of organic compounds or unhelpful by causing the destruction of organic matter during thermal extraction steps. Perchlorates are recognized as confounding minerals for thermal degradation studies. On heating, perchlorates can decompose to produce oxygen, which then oxidizes organic matter. Other common minerals on Mars, such as sulfates, may also produce oxygen upon thermal decay, presenting an additional complication. Different sulfate species decompose within a large range of temperatures. We performed a series of experiments on a sample containing the ferric sulfate jarosite. The sulfate ions within jarosite break down from 500°C. Carbon dioxide detected during heating of the sample was attributed to oxidation of organic matter. A laboratory standard of ferric sulfate ...
34 citations
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...Perchlorate species predominantly decompose at £ 600 C (Shimokawabe et al., 1977), so their presence on Mars is further implied by Phoenix Thermal Evolved Gas Analyzer (TEGA) results, which show the evolution of oxygen in the 300–600 C range (Hecht et al., 2009)....
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...Perchlorate species predominantly decompose at £ 600 C (Shimokawabe et al., 1977), so their presence on Mars is further implied by Phoenix Thermal Evolved Gas Analyzer (TEGA) results, which show the evolution of oxygen in the 300–600 C range (Hecht et al....
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TL;DR: In this article, the catalytic effects of doped or mixed CuO-Cr2O3 oxides on the thermal decomposition of ammonium perchlorate (AP) were investigated by using DTA, electrical conductivity and X-ray diffraction techniques.
Abstract: The catalytic effects of doped or mixed CuO-Cr2O3 oxides on the thermal decomposition of ammonium perchlorate (AP) were investigated by using DTA, electrical conductivity and X-ray diffraction techniques. The results obtained revealed that the decrease in the defect electron of CuO catalyst doped with 1 at.% Cr3+ inhibited its activity, while the opposite effect was observed when Cr2O3 was doped with 1 at.% Cu2+. On increase of the concentrations of both oxides, the catalyst containing 70 at.% Cr3+ was found to be the most active during the decomposition of AP. The existence of CuCr2O4 at this ratio was demonstrated by X-ray diffraction. The activity of this spinel was explained on the basis of a hopping mechanism between Cr3+/Cr4+ active sites. Finally, the activation energies of different decomposition stages of AP alone and mixed with catalysts were calculated.
31 citations
TL;DR: In this article, the green biotemplate Aloe vera plant extract has emerged as a better substitute of industrial surfactant poly(ethylene)glycol of molecular weight 8000 (PEG8000) in synthesis of ZnO nanorods using a simple sonoemulsion route.
Abstract: The green synthesis approach using ecofriendly biological precursors has gained world-wide popularity, reputation and recognition in the synthesis of several inorganic nanomaterials. This work demonstrates that a proper selection of biological precursor from the sustainable natural resources can effectively replace the commercial surfactant for fabrication of nanomaterials. Through this work, the green biotemplate Aloe vera plant extract has emerged as a better substitute of industrial surfactant poly(ethylene)glycol of molecular weight 8000 (PEG8000) in synthesis of ZnO nanorods using a simple sonoemulsion route. The colloidal growth of ZnO nanorods in PEG8000/Aloe vera -assisted sonoemulsion route has been elaborated in the context of relative supremacy of ultrasonic-assisted self-aggregation rate with steric-hindrance effect imposed by PEG8000/Aloe vera . The relative catalytic activity of PEG8000/Aloe vera synthesized ZnO nanorods, Co3O4 nanobelts and CuO nanorods in thermal decomposition of p...
25 citations
Cites background from "Effect of metal oxide additives on ..."
...Several metal oxides such as CuO (Patel 2013), Fe2O3 (Shimokawabe, Furuichi, and Ishii 1977), Al2O3 (Shimokawabe, Furuichi, and Ishii 1977), CoO (Li et al. 2008), MnO2 (Chandru et al. 2012), V2O5 (Zhang et al. 2014) and TiO2 (Fujimura and Miyake 2009) have shown catalytic activity in thermal decomposition of perchlorates....
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...Several metal oxides such as CuO (Patel 2013), Fe2O3 (Shimokawabe, Furuichi, and Ishii 1977), Al2O3 (Shimokawabe, Furuichi, and Ishii 1977), CoO (Li et al. 2008), MnO2 (Chandru et al. 2012), V2O5 (Zhang et al. 2014) and TiO2 (Fujimura and Miyake 2009) have shown catalytic activity in thermal…...
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TL;DR: In this article, it has been shown that metal oxide powders exhibited a remarkable acceleration effect on the decomposition of KClO 4, especially Fe 2 O 3 does not.
21 citations
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TL;DR: In this article, the thermal dehydration and decomposition of oxalates of Mg(II), Ca (II), Sr(II, Ba(II) and Ba(III) were investigated by means of X-ray powder diffraction analysis and reflectance and infrared spectroscopy.
Abstract: The thermal dehydration and decomposition of the oxalates of Mg(II), Ca(II), Sr(II), Ba(II), Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) were investigated by means of TG, DTA, DSC, EGA, X-ray powder diffraction analysis, and reflectance and infrared spectroscopies. In general, the temperature at which the oxalates were dehydrated increased with 1/r, where r denotes the radius of metal ion. The heats of dehydration (ΔHH2O) of the alkaline earth metal oxalates increased with 1/r, but those of transition metal oxalates decreased as 1/r increased. By considering the decomposition products, the reactions of anhydrous oxalates were classified into three groups and the relations between the decomposition temperatures and 1/r were discussed for each group.
65 citations