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1.
The thermal stability of the monodiazohydroborate NMe4[1‐N2B10H9] was studied by thermogravimetric analysis. Under two different atmospheres (air and argon), the thermal decomposition starts at a temperature between 140 and 160 °C. The decomposition residue obtained was separated on a silica gel column. 11B NMR, IR and electrospray mass spectroscopy analyses of the different fractions separated showed that the above decomposition produces (NMe4)2[B20H18] as major product (90%), along with smaller amounts of residual NMe4[1‐N2B10H9] (5%), (NMe4)2[B12H12] and boric acid. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
G. C. Colorio A. Auroux B. Bonnetot 《Journal of Thermal Analysis and Calorimetry》1992,38(12):2565-2573
Alumina-boria catalysts were prepared by impregnation of porous and non porous aluminas with various amounts of boron oxide. A calorimetric investigation of their acidity was performed by gaseous ammonia adsorption. The differential heat evolved decreases when the amount of boria on alumina increases while the corresponding number of acid sites, as determined by volumetry, increases with the amount of boron oxide. The thermal behaviour and the stability of the catalysts, when dehydration occurs, were studied by differential scanning calorimetry linked to thermogravimetry.
Zusammenfassung Mittels Imprägnierung von porösen und nichtporösen Tonerden mit verschiedenen Mengen Boroxid wurden Aluminiumoxid-Boroxid-Katalysatoren hergestellt. Durch Adsorption von gasförmigem Ammoniak wurde eine kalorimetrische Untersuchung ihrer Azidität durchgeführt. Die differentielle freigesetzte Wärme sinkt bei Zunahme der Boroxidmengen auf Tonerde, während die entsprechende Anzahl von Säurestellen mit der Menge von Boroxid zunimmt, wie durch Volummetrie festgestellt wurde.Das thermische Verhalten und die Stabilität der Katalysatoren wurden bei Vorkommen von Dehydratation mittels DSC in Verbindung mit TG untersucht.相似文献
3.
Perdigón-Melón J. A. Auroux A. Bonnetot B. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):443-451
As supported palladium oxide catalysts present the best performances in methane combustion in lean conditions, microcalorimetric
studies of the interaction between methane and palladium oxide or metallic palladium supported on Al2O3, ZrO2 and BN have been performed at 673 K. At this temperature methane reduced the palladium oxide, and the heat of reduction of
palladium oxide was shown to depend on the dispersion and on the support. The lowest heats of reduction corresponded to the
highest rates of methane combustion. Moreover methane reforming occurred on metallic palladium, producing hydrogen, and again
methane decomposition was shown to depend on the support.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Jean Senegas Anne Marie Villepastour Bernard Bonnetot 《Journal of Physics and Chemistry of Solids》1981,42(12):1061-1069
A low temperature wide-line NMR study has allowed a determination of the AI-H bond lengths in cryolite-type Na3AlH6. It was found from the thermal behavior of the proton lines that the |AIH6|3? octahedra reorient around a C4 axis. Starting below 170 K, this rotation can be hindered by lattice defects. Above room temperature it becomes isotropic, and a quick protonic exchange appears.The thermal narrowing of the linewidth and the T1 and T1ρ relaxation times lead to activation energies of about 0.38 eV for axial rotation and 0.51 eV for protonic exchange. The minimum in T1 is in good agreement with the exchange model. Absorption phenomena, as well as partial decomposition of Na3AlH6 during the heat treatments, explain the presence of small amounts of mobil hydrogen. 相似文献
5.
6.
The enthalpies of dissolution and dilution of LiBH4 and LiAlH4 in THF have been determined.Dissolutions are exothermic. The endothermic dilution of LiAlH4 suggests for this compound, either a dissociation or an association equilibrium. 相似文献
7.
Résumé L'hydrure d'aluminium AlH3- a été obtenu par action de LiAlH4 sur AlCl3 ou ZnCl2 dans l'éther éthylique. La décomposition thermique a été étudiée par thermogravimé trie sous pression réduite (10–2 torr). La capacité calorifique molaire à 298 K, l'enthalpie de décomposition, ainsi que l'enthalpie de formation ont été déterminées avec un microcalorimètre Calvet.
Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le laboratoire de Thermochimie Minérale avec la Direction des Recherches et Moyen d'Essai. Nous remercions bien vivement cet organisme de l'aide qu'il nous a apportée. 相似文献
Aluminium hydride,-AlH3, was prepared by reaction of LiAlH4 on A1C13 or ZnCl2 in diethyl ether. Thermogravimetry was used to investigate its thermal decomposition under low pressure (10–2 torr). The molar heat capacity at 298 K, the heat of decomposition, and the heat of formation, were measured with a Calvet microcalorimeter.
Zusammenfassung Aluminiumhydrid AlH3- wurde durch Einwirkung von LiAlH4 auf AlCl3 oder ZnCl2 in DiÄthylether hergestellt. Die Thermo gravimetrie wurde zur Untersuchung der thermischen Zersetzung bei niedrigem Druck (10–2 torr) herangezogen. Die molare WÄrmekapazitÄt bei 298 K, die Zersetzungsenthalpie sowie die Bildungsenthalpie wurden mit einem Calvet-Mikrokalorimeter bestimmt.
— - l3 LiAlH4 ll3 ZnCl2 . (10–2 ) . 298 , .
Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le laboratoire de Thermochimie Minérale avec la Direction des Recherches et Moyen d'Essai. Nous remercions bien vivement cet organisme de l'aide qu'il nous a apportée. 相似文献
8.
Postole G Gervasini A Guimon C Auroux A Bonnetot B 《The journal of physical chemistry. B》2006,110(25):12572-12580
In this article, we report how variations in the preparation method of boron-nitride-supported noble metal catalysts may influence the surface characteristics of the active phase and consequently the potential applications as catalysts for oxidation reactions. The deposition and the dispersion of the active phase are strongly influenced by the preparation process and in particular by the protic or aprotic solvent used as the dispersing phase; in this study, benzene, glyme, water, tetrahydrofuran, diglyme, 2-propanol, and glycol have been investigated. Characterization techniques, such as Brunauer-Emmett-Teller, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, have been used to study the influence of the choice of a solvent phase on the particle size and dispersion of the metal deposited on the BN support. The modifications undergone by the support during the deposition of palladium in different solvents have also been studied. Through the use of the same deposition procedure, different noble metal coatings (Pt, Pd, Au, and Ag) have been prepared. The acidic and redox characteristics of the resulting samples were characterized by temperature-programmed reduction and adsorption microcalorimetry. The catalytic performances of these materials were tested in the total oxidation of methane in lean conditions (excess oxygen and presence of water). 相似文献
9.
From calorimetric measurements a model of solution is proposed for LiAlH4 in THF. It is ionised as LiAlH4 ? Li+ + AlH?4. For this reaction, ΔHi = 3.05 kcal mol?1 and the dissociation constant is K = 0.11. 相似文献
10.
Laetitia Laversenne Christelle Goutaudier Rodica Chiriac Catherine Sigala Bernard Bonnetot 《Journal of Thermal Analysis and Calorimetry》2008,94(3):785-790
The hydrogen storage capabilities of alkaline borohydrides through a hydrolyzing process were determined by taking into consideration
the hydration of the end products. Comparison of LiBH4, NaBH4 and KBH4 showed their storage capacities to be dependent on the composition of the metaborate formed. This composition is ruled by
the hydrolysis conditions, especially the temperature reached during the reaction and the stability of the hydrates. The borohydride
with the highest hydrogen content in the solid state, LiBH4, could be less efficient than KBH4 if the hydrolysis is performed at 120°C. 相似文献