The thermal decomposition of the carbonate reaction products

1995 ◽  
Vol 43 (1) ◽  
pp. 149-156 ◽  
Author(s):  
M. A. Wójcik
Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2451 ◽  
Author(s):  
Jun Zhang ◽  
Junyi Huang ◽  
Xiang Fang ◽  
Yuchun Li ◽  
Zhongshen Yu ◽  
...  

To better understand the thermal decomposition and reaction process of a fluorine-containing powdery thermite, PTFE/Al/MnO2, reactions at different temperatures were investigated by the TG/DSC-MS technique. The corresponding reaction products were characterized with XRD phase analysis. Another three thermite materials, i.e., PTFE/Al, Al/MnO2, and PTFE/MnO2, were also prepared for comparison. Results showed that PTFE behaved as both oxidizer and reducer in PTFE/Al/MnO2 fluorinated thermite. The thermal decomposition and reaction process of as-fabricated ternary thermite could be divided into two stages—the mutual reaction between each of PTFE, Al, and MnO2 and the subsequent reaction produced between Al and Mn2O3/Mn3O4/MnF2. Compared with the three control systems, the specially designed ternary system possessed a shorter reaction time, a faster energy release rate, and a better heat release performance.


By mass-spectrometric analysis combined with vapour-phase chromatography the reaction products from the thermal decomposition of ether have been determined at various stages of the reaction (uninhibited and inhibited by nitric oxide) for initial ether pressures of 80 to 1000 mm. The effects of added hydrogen and of carbon tetrafluoride on the composition of the products have also been examined. No major changes in the chemistry of the reaction occur with these variations in conditions. Factors are given for calculating true rate constants from pressure changes accompanying the reaction. Corrected values of rate constants vary with the conditions in the same way as the values derived from uncorrected pressure changes, the correspondence being close for the uninhibited reaction.


1988 ◽  
Vol 41 (2) ◽  
pp. 263 ◽  
Author(s):  
PJ Mineely

The thermal decomposition of the chromates FeOHCrO4, KFe3(CrO4)2(OH)6, Fe2(CrO4)3.H2O and Fe2(CrO4)3.3H2O have been studied by thermal analysis and Mossbauer spectroscopy. The possible presence of Fe2O(CrO4)2 as a second phase formed during the decomposition is discussed. Final products in all reactions were oxides of iron(III) and chromium(III). In addition K2Cr2O7 Was present in the reaction products for KFe3(CrO4)2(OH)6.


2009 ◽  
Vol 1216 ◽  
Author(s):  
Daniel Reed ◽  
David Book

AbstractWith relatively high gravimetric and volumetric hydrogen storage capacities, borohydrides have attracted interest as potential hydrogen storage media. Lithium borohydride has a maximum theoretical gravimetric hydrogen storage density of 18.4 wt%, and has been shown to be reversible when heated to 600°C in 350 bar hydrogen1. It is hoped that a greater understanding of the decomposition and reformation mechanisms, may lead to the development of LiBH4-based materials that can absorb and desorb hydrogen under less extreme conditions. However, these studies have proved a challenge: currently most in-situ investigations have used x-ray diffraction or neutron diffraction however these cannot readily give information on non-crystalline or liquid phases. The preparation of samples measured ex-situ via XRD, NMR2 and Raman3 have shown the reaction products and stable intermediates during the thermal decomposition, however, it is very difficult to detect short lived intermediate (or byproduct) species. Raman spectroscopy has the advantages that: materials with only short-range order can be analysed; and by focusing the laser on regions in a sample the reaction path can be monitored with changing temperature with a rapid scan rate.After heating lithium borohydride through its phase change and melting point, shifts in peak position and peak width were observed, which agreed with other studies4. A sample was also heated to 500°C (under 1 bar Ar) to decompose the sample. A number of intermediates and reaction products have been predicted and observed ex situ. This work shows the in situ formation of lithium dodecaborane (Li2B12H12) and amorphous boron from liquid lithium borohydride. It is therefore possible to determine at what temperatures certain intermediates and products form.


2006 ◽  
Vol 911 ◽  
Author(s):  
Vladimir Sevastyanov ◽  
Yurij Ezhov ◽  
Roman Pavelko ◽  
Nikolaj Kuznetsov

AbstractHomologues with the general stoichiometry a(SiCl4) : bSi : cC : d(SiC) are shown to be potential precursors for the low-temperature gas-phase synthesis of silicon carbide. Thermal decomposition of these precursors yields the chemically stable gaseous species SiCl4 and condensed Si, C, SiC, SiC+Si, or SiC+C. Thermodynamic modeling of the thermal decomposition of octachlorotrisilane, Si3Cl8, is used to analyze the key features of the thermolysis of perchlorosilanes with the general stoichiometry a(SiCl4) : bSi. The equilibrium compositions of reaction products in the Si3Cl8+CO system are determined. This reaction system enables low-temperature (400 – 1200 K) synthesis of silicon carbide.


The introduction of chlorine atoms into organic compounds causes marked changes in properties which can often be explained in terms of a displacement of electrons under the influence of the substituent. It is an interesting question how far these influences will show themselves in the kinetic behaviour of the substituted molecules. Accordingly the thermal decomposition of chloral and its catalysis by iodine have been studied. The decomposition is a homogeneous gaseous reaction which can be compared with the decomposition of acetaldehyde and propionic aldehyde. Apparatus The apparatus was of the usual type, with a silica reaction vessel heated in an electric furnace. A tube led to a capillary mercury manometer outside the furnace, and the course of the reaction was followed by observing the rate of pressure increase. In view of the relatively high boiling point of chloral it was necessary to keep all the connecting tubes heated to 80°-90° C. Considerable difficulty was experienced with the lubricants for the stop-cocks operating at this temperature. A special high temperature vapourless grease was used, but even this showed a tendency to run and foul the connecting tubes. The reaction products also tended to foul the apparatus so that frequent cleaning of the whole, including the manometer and the mercury pump, was required.


1992 ◽  
Vol 296 ◽  
Author(s):  
Tod R. Botcher ◽  
Charles A. Wight

AbstractThin films of RDX (1,3,5-trinitro-1,3,5-triazine) have been prepared by vapor deposition onto a 77 K substrate window and pyrolyzed with a pulsed CO2 laser. Each sample is rapidly quenched after the laser pulse by heat conduction into the cold substrate, and the initial reaction products are trapped on the window for examination by transmission FTIR spectroscopy. We have detected N2O4, the dimer of nitrogen dioxide, as an initial condensed phase pyrolysis product, confirming that scission of one of the N-N bonds is the first step in the reaction mechanism. No evidence was found for formation of methylene nitramine via a proposed concerted depolymerization pathway.


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