A mathematical model of the thermal decomposition of basic aluminium ammonium sulfate has been developed. The construction of the model consisted in simulation of TG and DTG curves, with the use of kinetic parameters identified on the basis of results obtained in measurements of the rate of thermal dissociation of the compound under isothermal and non-isothermal conditions.
Zusammenfassung Es wurde das mathematische Modell fur thermische Zersetzung des basischen Ammoniumaluminiumsulfats bearbeitet. Die Struktur des Modells bestand in der Nachbildung von thermogravimetrischen Kurven TG, DTG mittels der kinetischen Parameter, die auf Grund der isothermen und der nichtisothermen Ergebnisse der Untersuchungen nach der Dissoziationsgeschwindigkeit von Verbindungen identifiziert wurden.
Résumé Un modèle mathématique décrivant la décomposition thermique du sulfate basique d'aluminium et d'ammonium est présenté.La méthode consiste à simuler les courbes thermogravimétriques TG et TGD à l'aide des paramètres cinétiques identifiés sur la base des résultats des déterminations isothermes et nonisothermes de la vitesse de la dissociation du composé.
The rate of release of sulfur oxides from basic aluminium ammonium sulfate (BAAS) under isothermal, isobaric conditions in a hydrogen atmosphere was studied.Twomethods of selection of theg() function which best describes the isothermal experimental data are discussed.The first method is based on statistical criteria and the second one on the the use of a reduced-time scale. Kinetic parameters for the thermal decomposition of BAAS in a hydrogen atmosphere are reported.
Zusammenfassung Unter isothermen, isobaren Bedingungen wurde die Geschwindigkeit der Freisetzung von Schwefeloxiden aus basischem Aluminiumammoniumsulfat (BAAS) untersucht.Es werden zwei Verfahren zur Auswahl derjenigeng()-Funktion diskutiert, die die isothermen Ergebnisse am besten wiedergibt.Das erste Verfahren beruht auf statistischen Kriterien, dem zweiten lag eine reduzierte-Zeitskala zugrunde. Kinetische Parameter für die thermische Zersetzung von BAAS in Wasserstoff werden beschrieben.
Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60th birthday 相似文献
Using the method of Bolles and Drago (1) the thermodynamic properties of drug - aromatic amino acid complexes were determined calorimetrically. The comparison of Kc evaluated from vapour pressure osmometry. ORD, partition and calorimetry shows a considerable agreement, whereas the data calculated from solubility measurements differ widely from our results. Qualitatively the relationship between solubilisation through different salts and ΔG0 for the complexation with the same salts could be demonstrated. Methylxanthines form complexes with anions and cations, the complex formation in H2O and D2O, determined calorimetrically, shows the greater stability of the complexes in D2O. 相似文献
A study was made of the effect of an atmosphere of H2+CO (a 3∶1 molar mixture) on the mechanism and the kinetics of desulfuration of basic aluminium-ammonium sulfate under variable pressures of hydrogen and carbon monoxide. The temperature region of the process, the nature of almost all the solid intermediates, and the equations and kinetic parameters relating to the rate of desulfurization of the compound for α<0.6 were determined. Despite the complexity of the process, the results permitted determination of the temperature and the composition of the gas phase necessary for the process of desulfuration to occur and for aluminium oxides with the required properties to be obtained. 相似文献
The kinetics of individual stages of thermal dissociation of basic aluminium potassium sulfate (BAPS) were studied thermogravimetrically under isobaric and isothermal conditions at a reduced pressure of the order of 10?3 hPa and in the atmosphere of gaseous products of the reaction (H2O, SO2).The kinetic parameters of all the reaction stages have been identified and the nature of the stages and the effect of changes of the reaction of conditions on the course of the processes have been determined. 相似文献
Summary Thermal decomposition of nanosize ammonium sulfate obtained as a by-product in a new electron-beam technology cleaning up
waste gases from thermal power stations was studied. DTA-TG-DTG curves were used to characterize thermal properties of the
new products obtained under different technological conditions. High quality of ammonium sulfate from Merck was used as a
reference material. Ammonium sulfate was the main component in all the products and their thermal behavior was similar to
that of the reference. Only the solid product obtained with the highest norm of ammonia contained about 3.2% ammonium nitrate.
Thermoanalytical methods can successfully be applied for control the quality of the by-products from E-beam desulfurization
technology. It was found that the thermal stability of the nanosize ammonium sulfate was the same as that of the reference
ammonium sulfate. 相似文献
The rate of release of sulphur oxides from basic aluminium potassium sulphate was studied in a hydrogen atmosphere under isothermal-isobaric conditions, and the kinetic parameters of the process were determined by the statistical criteria method.
Zusammenfassung Es wurde in Wasserstoff unter isothermen-isobaren Bedingungen die Geschwindigkeit der Freisetzung von in basischem Aluminium-kaliumsulfat in Form von Aluminiumsulfat gebundenen Schwefeloxiden untersucht und die kinetischen Größen dieses Prozesses bestimmt.
The author would like to express her thanks to Professor J. Pysiak for valuable discussions. 相似文献
The thermal behavior of Tunisia phosphorite and ammonium sulfate mixtures are examined by non-isothermal thermogravimetry
in air atmosphere. It has been shown that the thermal stability of mixtures have different behavior after mechano-chemical
treatment due to phase changes in the mixtures. New solid phases are confirmed by the stages and rate of mass changes and
also by the heat effects observed. New phases are also confirmed by using X-ray diffraction method. Based on the data obtained
by the mechanism of chemical transformations is proposed. The kinetics of mechano-activated mixtures decomposition is significantly
influenced by the time of treatment and proceeds in few stages. Stage I is attributed to the effect of partially ammonia releasing,
when the next stages are associated with the decomposition of apatite structures. Because of the interfacial interactions
during mechano-chemical treatment insoluble phosphorous forms from apatite structures are transformed to the soluble forms
suitable for plants nutrition. The results have shown that the soluble form can be controlled by the initial components ratio
and conditions of treatment on the way to obtain slow releasing nutrition products.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
The stages of thermal decomposition of basic aluminium-ammonium sulfate (BAAS) in hydrogen atmosphere were studied with use of differential thermal analysis (DTA), thermogravimetric (TG), X-ray diffraction phase analysis (XRD), and chemical analyses. It has been found that hydrogen greatly influences the process of the desulfurization of the investigated compound: this process occurs at lower temperatures as compared to the desulfurization process in air. The final decomposition product of the basic salt at 1223 K is-Al2O3. The experimental part is preceded by the thermodynamic analysis of the desulfurization process of BAAS in hydrogen atmosphere, and its results have been correlated with experimental tests.
Zusammenfassung Die Stufen der thermischen Zersetzung von basischem Aluminium Ammonium Sulfat (BAAS) in WasserstoffatmosphÄre wurden unter Verwendung von Differenzthermoanalyse (DTA), Thermogravimetrie (TG), röntgenographischer Phasenanalytik (XRD) und chemischer Analytik untersucht. Es wurde festgestellt, dass Wasserstoff den Desulfurierungsprozess der untersuchten Verbindung stark beeinflusst, indem dieser bei tieferer Temperatur ablÄuft als die Desulfurierung in Luft. Das Endprodukt der Zersetzung des basischen Salzes bei 1223 K ist-Al2O3. Die experimentellen Resultate wurden mit den Ergebnissen einer vorgÄngig durchgeführten thermodynamischen Betrachtung der Desulfurierung von BAAS in WasserstoffatmosphÄre korreliert.
Mixed crystals of various proportions of zinc magnesium ammonium sulfate were grown by slow evaporation of aqueous solution at room temperature. The bright and transparent crystals obtained were characterized through thermal (TG–DTA) and FTIR spectral analyses. A fitting decomposition pattern for the compound was formulated on the TG curve which shows two stage mass losses between 133 and 478.75 °C. DTA curve shows exothermic peaks in this temperature range supporting the formulated decomposition pattern. The FTIR spectra show the vibration frequencies due to the formation of zinc magnesium ammonium sulfate mixed crystals. Detailed structural analysis of the compound is under progress. 相似文献
The process of obtaining a special aluminium oxide by means of the thermal dissociation of a basic aluminium-potassium sulfate in the presence of carbon (soot) and water vapour was studied. Under these conditions, the dissociation of the basic salt occurs at a lower temperature than in presence of air. K2O-Al2O3 and/or Al2O3 are formed as fine-grained reaction residues, depending on the final temperature. The technologically useful range of temperatures for the process was established.
Zusammenfassung Der Herstellungsprozess eines speziellen Aluminiumoxids durch thermische Zersetzung von basischem Kalium-aluminium-sulfat in Gegenwart von Kohlenstoff (Russ) und Wasserdampf wurde untersucht. Unter diesen Bedingungen verläuft die Zersetzung bei tieferer Temperatur als in Gegenwart von Luft, und K2O.Al2O3 und/oder Al2O3 werden als feinkörnige Endprodukte (abhängig von der Endtempeatur) erhalten. Der technologisch günstigste Temperaturbereich für den Prozess wurde ermittelt.
The stages of thermal decomposition of basic aluminium potassium sulphate were studied with the use of differential thermal analysis (DTA), thermogravimetry (TG), mass spectrometry (MS), IR spectroscopy (IR), and X-ray diffraction phase analysis (XRD). The individual stages of the decomposition were determined and both solid and gaseous products of the dissociation were identified. On the basis of spectrometric data and thermodynamic calculations the possibility of the occurrence of the SO in the gaseous reaction products is discussed. 相似文献
The influence of calcination conditions on changes in phase composition and porous structure was studied for hydrous aluminium oxide, obtained by leaching out potassium salts from the products of roasting basic aluminium-potassium sulfate in hydrogen atmosphere at 600°C. The product of calcination at 350°C in vacuum has the most developed porous structure with most pores of internal radius within 10–60 Å. Calcination in air atmosphere at temperatures 700, 800, 900, or 1000°C resulted in decrease of specific surface of aluminium oxide and increase of the share of pores with internal radius above 60 Å in the overall porosity of the samples. The reconstruction of the porous structure proceeds mainly as a result of coalescent sintering. 相似文献
The mechanism of thermal decomposition of aluminum sulfate has been investigated in the 500–700°C temperature range using a flow reactor system with the emitted gaseous sulfur oxides collected in a Goksøyr—Ross coil and a hydrogen peroxide impinger. Sulfur trioxide (SO3) was found to be the primary sulfur oxide released during thermal decomposition (1). Less than 3% of the released sulfur oxides were sulfur dioxide (SO2), indicating that the SO3 dissociation reaction (2) is slow relative to the residence time of the SO3 in the reactor (～ 1 sec). The experimental technique should be readily adaptable to the study of the thermal decomposition of other metal sulfates. 相似文献
The reaction between ammonium sulphate with aluminium oxide was studied. It was confirmed by X-ray diffraction and chemical analysis that three intermediate reaction products, (NH4)3Al(SO4)3, NH4Al(SO4)2 and Al2(SO4)3, are formed. The thermal decompositions of these three compounds were carried out. It has been shown that the same rate law is valid for them. The activation energies for (NH4)3Al(SO4)3, NH4Al(SO4)2 and Al2(SO4)3 are 95.9, 177.9 and 291.0 kj/mol, respectively.
Zusammenfassung Die Reaktion von Ammoniumsulfat mit Aluminiumoxid wurde untersucht. Durch Röntgendiffraktion und chemische Analyse wurde bestätigt, daß drei Zwischenprodukte (NH4)3Al(SO4)3, NH4Al(SO4)2 und Al2(SO4)3 gebildet werden. Die thermische Zersetzung der drei Verbindungen wurde durchgeführt. Es wurde gezeigt, daß für alle drei dasselbe Geschwindigkeitsgesetz Gültigkeit hat. Die Aktivierungsenergien für (NH4)3Al(SO4)3, NH4Al(SO4)2 und Al2(SO4)3 sind 95.9, 177.9 und 291.0 kJ/Mol.
The authors are grateful to Dr. H. Osada and Mr. H. Nakamura, Department of Environmental Engineering, Kyushu Institute of Technology, for their helpful discussions. 相似文献
Aluminium can be determined gravimetrically by the homogeneous precipitation of basic aluminium benzoate. The benzoate method is more rapid and has other advantages over the basic succinate and ammonia methods. It is concluded that aluminium can never be separated from beryllium by any method which relies on precipitation of their hydroxides or basic salts. 相似文献
The phase equilibria for the reduction of SmMnO3 with hydrogen were studied by the static method using a circulation vacuum setup in conjunction with XRD analysis of quenched solid phases. It was established that, over a temperature range of 973–1123 K and a pressure range of 10?10–10?16 Pa, SmMnO3 dissociates by the reaction (1/2)Sm2O3 + MnO + (1/4)O2; in this case, the temperature dependence of the equilibrium oxygen pressure and the Gibbs energy change can be described by the equations log $p_{O_2 } $ [Pa] = 25.35 ? 39150/T ± 0.1, ΔG°T, kJ/mol = 187.62 ? 0.09T ± 1.62, respectively. Based on the experimental data, the standard thermodynamic functions of formation of SmMnO3 from elements were calculated: ΔH°T = ?1485.706 kJ/mol and ΔS°T = 244.39 J/(mol K). 相似文献
The establishment of equilibrium in the chemical reaction X2+M 2X+M is examined. All possible transitions between the vibrational levels and the continuous spectrum are considered. Taking account of two relaxation times, an expression is obtained for the concentration of the X atoms and the chemical reaction rate as a function of time. The conditions under which the dependence of the chemical reaction rate on time acquires an exponential nature are determined. An expression free from the requirement that the initial concentrations of X-atoms and X2 molecules should be close to their equilibrium values is obtained for the rate constant.In conclusion, the authors thank Prof. N. D. Sokolov for discussion of the work. 相似文献
The thermal decompositions of the crystalline aluminium hydroxides hydrargillite, bayerite and nordstrandite were investigated by thermogravimetry, differential thermal analysis, X-ray diffraction and infrared spectrophotometry. It was found that these aluminium hydroxides undergo thermal decomposition in the following sequences: hydrargillite-1
Zusammenfassung Die thermische Zersetzung von kristallinen Aluminiumhydroxiden, wie Hydrargillit, Bayerit und Nordstrandit, wurde thermogravimetrisch, differentialthermoanalytisch, röntgendiffraktometrisch und IR-spektrophotometrisch untersucht. Es wurde festgestellt, da\ diese Aluminiumhydroxide in der folgenden Reihenfolge zersetzt werden: Hydrargillit-I
