The influence of some transition and inner transition metal oxides on the thermal decomposition of molten lithium perchlorate
TL;DR: In this article, the influence of the oxides TiO2, V2O5, Co2O3, MnO2 and Tb4O7 on the thermal decomposition of lithium perchlorate trihydrate was surveyed.
Abstract: The influence of the oxides TiO2, V2O5, Co2O3, MnO2, Fe2O3, Co2O3, NiO, CuO, La2O3, CeO2, Pr6O11, Eu2O3, Gd2O3 and Tb4O7 on the thermal decomposition of lithium perchlorate trihydrate, was surveyed. Most of the oxides lowered the decomposition temperature of the anhydrous perchlorate; but their weight-loss matched the results obtained by heating lithium perchlorate without additives. Chromium(III) oxide and vanadium(V) oxide were exceptional.
Citations
More filters
TL;DR: In this paper, the reaction at 300°C between molten lithium perchlorate and chromium(III) oxide gave lithium dichromate, and a reaction mechanism was proposed.
Abstract: The reaction at 300°C between molten lithium perchlorate and chromium(III) oxide gave lithium dichromate. When lithium perchlorate and chromium(III) oxide were in the formula weight ratio of 2:1 respectively, the chromium was oxidized completely into the hexavalent oxidation state, and only a negligible chloride percentage of 0·1 remained in the resulting lithium dichromate.
Different formula weight ratios were taken for the reaction at 300°C. In the runs where the formula weight ratios of the perchlorate and oxide were lower than 2:1, the amount of chromium oxidized was higher than expected by the proposed route, and an explanation is given. Reactions with 51Cr2O3 showed that a very small amount of chromium volatilized.
Results obtained from experiments both in vacuum and air were in very good agreement. A reaction mechanism is proposed.
5 citations
TL;DR: In this paper, the catalytic activity of rare earth oxides (REO) was studied at 723 K and α−t plots for pure salt as well as mixtures indicate that the process follows: initial gas evolution, a short acceleratory and a long decay stages.
Abstract: Catalytic activity of rare earth oxides (REO); La2O3, Sm2O3, Gd2O3 and Ce2O3 on the isothermal decomposition of barium oxalate has been studied at 723 K. The α−t plots for pure salt as well as mixtures indicate that the process follows: initial gas evolution, a short acceleratory and a long decay stages. The results of the kinetic analysis show that Prout-Tompkins relationship and two-dimensional phase boundary reaction give best fit of the data for both pure salt as well as mixtures. The rate constants of acceleratory and decay periods are enhanced remarkably by adding REO admixtures and their catalytical activity is in the order La2O3>Sm2O3>Gd2O3 >Ce2O3. The plausible mechanism of decomposition and the role of admixture there on has been discussed in the light of electron transfer process.
5 citations
TL;DR: In this paper, the thermal decomposition of an intimate mixture of thallium(I) perchlorate and chromium(III) oxide revealed that chromium-III oxide lowers the decomposition temperature of the mixture and is oxidized into hexavalent state.
Abstract: Thermal decomposition of an intimate mixture of thallium(I) perchlorate and chromium(III) oxide revealed that chromium(III) oxide lowers the decomposition temperature of thallium(I) perchlorate and is oxidized into hexavalent state to give thallium(I) dichromate. The thermal decomposition was followed by constant temperature heating, thermogravimetry and differential thermal analysis. The reaction products were characterized by chemical analysis, X-ray diffraction and infrared spectral measurements.
3 citations
TL;DR: In this article, the effect of CeO2 on the thermal decomposition of the persulfates from ambient to 1050°C, using the derivatograph, has been investigated, and it has been found that CeO 2 lowers the initial decomposition temperatures of these two persulfate by an amount which is directly proportional to the percentage of the oxide in the mixture through a catalytic effect.
Abstract: TG and DTA investigations, under static air atmosphere, of mixtures of CeO2 with Na2S2O8 and K2S2O8 in different molar ratios (1 : 6, 1 : 3, 1 : 1, and 2 : 1) are reported. The purpose of these investigations is to study the effect of CeO2 on the thermal decomposition of the persulfates from ambient to 1050°C, using the derivatograph. It has been found that CeO2 lowers the initial decomposition temperatures of these two persulfates by an amount which is directly proportional to the percentage of the oxide in the mixture through a catalytic effect. Reaction products are identified by X-ray diffraction analysis. The stoichiometric molar ratio of the solid state reaction is found to be 2 : 3 CeO2 : Na2/K2/S2O8, which leads to the formation of double salts for both persulfates, namely, NaCe(SO4)2 and KCe(SO4)2.
2 citations
TL;DR: In this article, three binary systems, each consisting of mixtures of different molar ratios of a rare earth (4f metal) sesquioxide and sodium or potassium persulfate (peroxodisulfate) have been investigated under static (air) atmospheres using a derivatograph.
Abstract: Three binary systems, each consisting of mixtures of different molar ratios of a rare earth (4f metal) sesquioxide and sodium or potassium persulfate (peroxodisulfate) have been investigated under static (air) atmospheres using a derivatograph. For each system (R2O3 - M2S2O8, whereR is Sm, Gd, or Dy, andM is K or Na), the molar ratios that represent stoichiometric reactions were fixed. Calculations were based on data obtained from T, TG, DTG and DTA curves. Intermediate and final products were mainly identified by X-ray diffractometry. Double salts of Sm, Gd, and Dy were thermally prepared by solid-state reactions. It was found that one such double salt KDy(SO4)2, forms a eutectic mixture with K2SO4 and also that both Gd and Dy sesquioxides behave asp-type semiconductors and therefore exhibit catalytic activities towards the thermal decomposition of persulfates and pyrosulfates. Optimal catalysis was obtained with molar ratios of 1∶3. The activities increased as the ionic radii of these metals decrease: Sm, Gd, Dy.
References
More filters
TL;DR: In this article, a detailed study of the components in the system metal oxide-silica-water occurring during the preparation of hydrogenation catalysts with added silica, has been published.
Abstract: So far various metal hydrosilicates have been described in literature, but a detailed study of the components in the system metal oxide-silica-water occurring during the preparation of hydrogenation catalysts with added silica, has not been published. The results of a study of the system NiO-SiO2-H2O are given in this article, which also describes influence of the silica on the reducibility of the compounds.
The formation of nickel hydrosilicates under various conditions was studied by means of X-ray diffraction and thermal analysis. At relatively low temperatures (under 100° C) badly crystallized compounds are formed; thermal analysis indicated the presence of incomplete hydrosilicates, viz. nickel antigorite and/or nickel montmorillonite. The degree of crystallization of these hydrosilicate gels can be much improved by hydrothermal treatment.
The stable end products resulting from this treatment are Ni(OH)2, Ni3(OH)4Si2O5 (nickel antigorite), Ni3(OH)2(Si2O5)2 (nickel montmorillonite) and SiO2 (quartz).
The reducibility with hydrogen was measured as a function of the temperature. It varies greatly both with the silica content and with the degree of perfection of the hydrosilicate structure, the hydrothermally treated nickel montmorillonite being of all the most difficult to reduce. Generally the reduction leads to formation of nickel in a cubic form; however in the case of the hydrothermally treated nickel montmorillonite and nickel antigorite gels there are indications that part of the reduced nickel atoms remain in the places they occupied as ions in the hydrosilicate structure.
48 citations