Mechanism of reactions in mixtures of calcium polyphosphate with apatite and accompanying minerals during heating

The thermal interaction of Kovdor apatite, calcite, dolomite and forsterite with calcium polyphosphate up to 1200 °C were studied by chemical, thermal (under dynamic and quasiisothermal and isobaric conditions), X-ray, electronmicroscopic and chromatographic methods. It was found that the accompanying minerals of apatite react with calcium polyphosphate at lower temperature in comparison with apatite, complicating the process of thermal defluorination of papatite.

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Zusammenfassung Die thermische Wechselwirkung von Kovdor-Apatit, Calcit, Dolomit und Forsterit mit Calciumpolyphosphat bei Temperaturen bis 1200 °C wurde durch chemische, thermische (unter dynamischen, quasiisothermen und isobaren Bedingungen), röntgenographische, elektronenmikroskopische und chromatographische Methoden untersucht. Es wurde festgestellt, daß die Begleitminerale des Apatits im Vergleich zum Apatit selbst bei niedrigeren Temperaturen mit Calciumpolyphosphat reagieren und so den Prozeß der thermischen Entfluorierung von Apatit komplizieren.

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, , 1200° , ( ), , - . , , .

     

Thermal characterization of bismaleimide blends

4,4-bismaleimidophenyl methane (BM) and 3,3-bismaleimidophenyl sulfone (BS) were blended in solution using weight ratios 31 (MS31), 21 (MS21), 11 (MS11), 12 (MS12) and 13 (MS13). Chain extended bismaleimide resins were also prepared by treating BS/BM with 4,4-diaminodiphenyl ether in molar ratios of 10.3 (BM-E and BS-E resins). These resins were also blended with bismaleimides and the curing characteristics were evaluated by differential scanning calorimetry. Increase in BM content in BMBS blends or increase in chain extended bismaleimide content in BM-EBS or BS-E BM blends resulted in a reduction of melting and curing temperatures. Indication about the extent of cross-linking was obtained from solubility measurements (in DMF) of isothermally cured resins (180 °C, lh and 220 °C, lh in an air oven). Thermogravimetric analysis of samples isothermally cured at 180 °C and 220 °C (lh each) was carried out in nitrogen atmosphere. Improvement in thermal stability of chain extended bismaleimides was observed on blending.

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Zusammenfassung 4,4-Bismalimidophenyl-methan (BM) und 3,3-Bismalimidophenyl-sulfon (BS) wurden in Lösung in den Gewichtsverhältnissen 31 (MS31), 21 (MS21), 11 (MS11), 12 (MS12) und 13 (MS13) gemischt. Auch kettenpolymerisierten Bismalimid-Harze wurden durch Behandlung von BS/BM mit Diaminodiphenylether im Molverhältnis 10,3 dargestellt (BM-E- und BS-E-Harze). Die Kennwerte der Aushärtung von Mischungen dieser Harze mit den Bismalimiden wurden mittels DSC ermittelt. Eine Erhöhung des BM-Gehaltes in den BM BS-Mischungen oder des Gehaltes der BM-E BS oder BS-E-Mischungen an kettenpolymerisierten Bismalimiden führt zu einer Erniedrigung der Schmelz- und Aushärtetemperaturen. Hinweise über den Vernetzungsgrad wurden aus Löslichkeitsmessungen (in DMF) von Isotherm (je 1 Stunde bei 180 und 220 °C in Luft) gehärteten Harzen erhalten. Die thermogravimetrische Analyse der Isotherm bei 180 bzw. 220 °C 1 Stunde ausgehärteten Proben wurde in Stickstoffatmosphäre ausgeführt. Die thermische Stabilität der Bismalimide wird durch Verschneiden verbessert.

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4,4-- () 3,3-- () 31 (MC 31), 21 (MC 21), 11 (MC 11), 12 (MC 12) 13 (MC13). - / 4,4- 10,3 ( - C-). - . - - - - , . ( 1 180 220°) . . - .

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The financial assistance provided by Department of Science and Technology is gratefully acknowledged.     

Catalytic conversion of alcohols, IX. Effect of temperature on the direction of elimination of water from a tertiary alcohol

The amount of 1-alkene formed by the dehydration of 2-methyl-2-butanol with several metal oxide catalysts parallels the temperature dependence of acetate pyrolysis where the amount of 2-methyl-1-butene increases with increasing temperature.

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1-, 2--2- , , 2--1- .

     

Systemes metaux alcalins-oxygene

Résumé Le comportement thermique du monooxyde de césium Cs₂O a été déterminé par analyse thermique différentielle, thermogravimétrie et diffraction X. L'utilisation de différents matériaux pour contenir ce produit a été nécessaire pour cerner les phénomènes propres à cet oxyde. On trouve la température de fusion de Cs₂O=495±5° et sa pression de vapeur égale à 10^–4 Torr à 240°. Aucune transformation allotropique n'est mise en évidence.

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The thermal behaviour of cesium monoxide (Cs₂O) was determined by differential thermal analysis, thermogravimetry and X-ray diffraction. The use of several materials as sample holders was necessary to clarify the properties of this oxide. The melting point of Cs₂O was found to be 495±5°, and its vapour pressure equal to 10^–4 torr at 240°. No allotropic transformation was observed.

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Zusammenfassung Es wird über die DTA, TG und röntgenographische Untersuchung des Caesium monoxyds berichtet. Verschiedene Materien als Probenbehälter wurden herangezogen damit die dem Oxyd eigene Eigenschaften klar festgelegt werden können. Der Schmelzpunkt von Cs₂O liegt bei 495±5°, der Dampfdruck beträgt 10^–4 Torr bei 240°. Es fand keine allotrope Umwandlung statt.

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Cs₂O , . , , . , 495±5 °C, 10^–4 240 °. .

     

Kinetic studies of thiolane synthesis from tetrahydrofurane and H2S

Kinetic studies of tetrahydrofuran reaction with H₂S were carried out in a flow-circulation reactor. Presumably, the reaction takes place through dissociative chemisorption of reactants and the interaction of surface structures formed to produce thiolane and water. A kinetic equation that agrees with the suggested mechanism has been derived.

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- H₂S. , . , .

     

Thermoanalytical testing of rubber-grade carbon blacks

The thermoanalytical behaviours of 9 carbon black types alone and in mixtures with rubber were studied. It was shown that the thermoanalytical tests carried out with rubber-grade carbon blacks help to predict their reinforcing effects. In measurements in the temperature range around 250° the weight losses indicate the activities of carbon blacks in rubber compounds. This test method may well supplement other test methods applied earlier to characterize carbon blacks.

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Zusammenfassung Das thermoanalytische Verhalten von 9 Typen von Ruß und in Gemischen mit Gummi wurde untersucht. Es wurde gezeigt, daß die an Ruß-Arten für die Gummi-Industrie durchgeführten thermoanalytischen Prüfungen sich für Voraussagen bezüglich der Verstärkungswirkung derselben eignen. Bei Messungen im Temperaturbereich um 250° zeigt der Gewichtsverlust die Aktivität des Rußes in den Gummiverbindungen an. Diese Testmethode kann die früher zur Charakterisierung von Ruß-Arten eingesetzten anderen Testmethoden gut ergänzen.

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Résumé On a étudié le comportement thermique de 9 types de noirs de fumée, seuls et en mélanges avec du caoutchouc. Les tests d'analyse thermique effectués sur des noirs de fumée destinés à l'industrie du caoutchouc permettent de prévoir l'effet renforçant de ceux-ci. Si les mesures sont effectuées vers 250°, la perte de poids indique l'activité des noirs de fumée dans le cautchouc. Cette méthode apporte des indications complémentaires des autres essais effectués précédemment pour caractériser les noirs de fumée.

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. , , , . , 250°, . , .

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Paper presented at the Scientific Session on Thermal Analysis held at Balatonfüred, Hungary, on 14–16 October, 1976.     

X-ray diffraction studies of platinum-alumina catalysts in a high-temperature chamber

X-ray diffraction studies of platinum-alumina catalysts in a high-temperature chamber have revealed that for the catalysts obtained by the reduction of preactivated samples, no complete reduction of platinum takes place.

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, , , .

     

Catalytic oxidation of cycloalkane heteroanalogs as a way to polyfunctional compounds

Liquid phase oxidation of cycloalkane diheteroanalogs catalyzed by compounds of Cu²⁺, Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺ has been studied. It has been established that these catalysts can be applied to intensify, oxidize and increase the selectivity of this process.

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: Cu², Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺. .

     

Rapid analysis of dosage forms of some pharmaceuticals by nonaqueous thermometric titrimetry

The use of the technique of solution thermochemistry is proposed for the rapid assay for quality control and quality assurance of dosage amounts of some ethical formulations of some antimalarial drugs. The active ingredients are chloroquine, hydroxychloroquine, dapsone, proguanil hydrochloride, and pyrimethamine.Assay is done without the separation of the excipients and without isolation or derivatisation of the analytes. The titrations are done in glacial acetic acid and utilise the catalysed hydrolysis of acetic anhydride by perchloric acid to indicate the endpoint of the reactions.The time taken for a typical assay, of a typical dosage amount is about 3–5 minutes. The reproducibility is of the order of 1% for the milligramme amounts of analyte present in the dosage amounts of the drugs.

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Zusammenfassung Es wird die Anwendung eines lösungsthermochemischen Verfahrens zu Schnellbestimmungen bei der Qualitätskontrolle und — sicherung von Wirkstoffeinsatzmengen einiger rezeptpflichtiger Präparate von einigen antimalarischen Arzneimitteln empfohlen. Die aktiven Bestandteile sind Chloroquin, Hydroxychloroquin, Dapson, Proguanilhydrochlorid und Pyrimethamin.Die Bestimmungen werden ohne jegliche Abtrennung der Bindestoffe und ohne Isolierung oder Derivatisierung der zu bestimmenden Substanzen durchgeführt. Die Titrierungen werden in Eisessig durchgeführt und bedienen sich der katalytischen Hydrolyse von Essigsäureanhydrid durch Perchlorsäure als Endpunktindikation der Reaktion.Die Dauer für eine typische Probe bei einer typischen Wirkstoffmenge beträgt etwa 3–5 Minuten. Die Reproduzierbarkeit liegt in der Größenordnung von 1% für Milligrammengen der zu analysierenden Stoffe im Arzneimittel.

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. , , , . - . . 3–5 . 1% , .

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We acknowledge the Nigerian Government for the provision of a grant to one of us (S.I.A.). We acknowledge the following for the gifts of samples of the authentic drugs and the tablets assayed in this work: Imperial Chemical Industries plc; May and Baker plc; Winthrop Laboratories plc; Wellcome Foundation (Medical Division).     

On the rate and deepness of 3-methylpentane hydrogenolysis over various transition metals

The 11 metals studied can be divided into two groups: Rh, Pd, Ir, Pt, inducing single, and Co, Ni, Cu, Ru, Ag, Re, Os, causing multiple breakdown of the 3-methylpentane molecule. A fragmentation factor was defined which was found to be independent of the preparation of the metal and its activity in hydrogenolysis.

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3- 11 : Rh, Pd, Ir Pt, 3-, Co, Ni, Cu, Ru, Ag, Re Os, . , , .

     

Reaction routes for hydrogenation of acetylene-ethylene mixtures using a double labelling method

Hydrogenation of C₂H₂:C₂H₄ mixtures using a double labelling method has been studied. Both in the presence and absence of ethylene the rate of acetylene hydrogenation on its partial pressure proceeds through a maximum and the rate is higher when ethylene is added. Using¹⁴C–C₂H₂ it was demonstrated that at low acetylene partial pressures the main route of acetylene hydrogenation was the formation of ethane and C₄ hydrocarbons. Using¹⁴C–C₂H₄ it was also shown that at certain acetylene partial pressures the formation of ethane from ethylene completely ceased. Different surface species are suggested and a reaction mechanism is proposed.

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C₂H₂:C₂H₄, . , , . C¹⁴–C₂H₂, , C₄. C¹⁴–C₂H₄, , . .

     

Thermochemical and kinetic studies on the effects of cobalt salicylate on the oxidative degradation of polystyrene

The effect of cobalt salicylate on the oxidative degradation and ignition of polystyrene has been studied. It was found that cobalt salicylate sensitizes both the degradation and ignition of polystyrene by facilitating electron-transfer processes in the propagation step. From thermochemical and kinetic studies it was found that the cobalt ion, owing to its ability to exist in variable valence states, promotes electron transfer in the propagation step of polymer degradation, increasing the rate of propagation and consequently the overall rate. Using solid-phase thermal ignition theory, an attempt has been made to explain the sensitization of ignition by the cobalt ion.

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Zusammenfassung Die Wirkung von Kobaltsalicylat auf den oxydativen Abbau und die Entzündung von Polystyrol wurde untersucht. Es wurde festgestellt, daß Kobaltsalicylat sowohl den Abbau als auch die Entzündung des Polystyrols durch Erleichterung von Elektrontransferprozessen im Kettenfortpflanzungsschritt begünstigt. Thermochemische und kinetische Untersuchungen ergeben, daß das Kobaltion infolge seiner Fähigkeit, in mehreren Valenzstufen aufzutreten, den Elektronentransfer im Kettenfortpflanzungsschritt erleichtert wodurch die Geschwindigkeit der Kettenfortpflanzung und damit die Geschwindigkeit des Gesamtprozesses erhöht wird. Basierend auf der Theorie der thermischen Festphasenentzündung wird ein Versuch unternommen, Erleichterung der Entzündung durch Kobaltionen zu erklären.

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. , , . , , , , . , .

     

Photoinduced oxygen adsorption of AgBr crystals at 77 K

Photoinduced adsorption (PIA) of oxygen molecules on AgBr films at 77 K has been experimentally observed and investigated. Lifetimes of PIA centers and desorption activation energies of O₂ molecules have been determined. The process is suggested to compete with the ionic step of AgBr photolysis.

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- () - AgBr 77 K. - O₂. , , - AgBr.

     

Thermal decomposition of peroxypropionyl nitrate: Kinetics of the formation of nitrogenous products

The Arrhenius expression for reaction 1, CH₃CH₂COO₂NO₂CH₃CH₂COO₂+NO₂, has been determined to be k=2×10¹⁵ exp (–12800/T)·s^–1. The free radical mechanism is the exclusive thermal decomposition mechanism of PPN. The main nitrogenous decomposition products of pure PPN are ethyl nitrate, nitrogen dioxide and methyl nitrate. In the presence of NO, ethyl nitrite is the major organitrogen product.

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CH₃CH₂COO₂NO₂CH₃CH₂COO₂+NO₂ : k=2·10¹⁵exp (–12800/T) ^–1. () - . , . NO .

     

DTA studies of 12CaO·7Al2O3 polymorphism

The polymorphism of 12CaO·7Al₂O₃ has been studied by means of a Setaram G-24 thermoanalyser and by X-ray diffraction using a Philips diffractometer. Thermal treatment was carried out at 1.3 Pa as well as in air atmosphere.

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Zusammenfassung Der Polymorphisms von 12CaO·7Al₂O₃ wurde mit Hilfe eines Setaram G-24 Thermoanalysators und durch Röntgenstrukturanalyse mittels eines Philips Diffraktometers untersucht. Die Wärmebehandlung geschah in Luft sowohl bei 1,3 Pa als auch bei Normaldruck.

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-24 12 ·7l₂₃. 1,3 , .

     

Consecutive hydrogenation of pseudoionon. Application of diffusion kinetic model to predict experimental reactor operation

A method for the calculation of fixed catalyst bed reactors by using a diffusion kinetic model is suggested. Correlation between calculated curves for the time distribution of the reaction mixture composition and experimental data is given.

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=qo . .

     

Testing of nickel phosphate (NiP) catalyst for ethylbenzene oxydehydrogenation by means of isopropanol dehydration

It has been shown that NiP catalyst, if fresh, contains a high concentration of the same type acid-base surface centers as those participating in i-PrOH dehydration on -Al₂O₃. The concentration of these centers diminishes rapidly after a modification of NiP surface in a stream of ethylbenzene (EtPh) oxydehydrogenation products.

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, NiP - , , i-PrOH -Al₂O₃. NiP .

     

Oxidative dehydrogenation of n-butane IV. Kinetic and catalytic activity of copper oxide

Copper oxide is moderately active and selective in the oxidative dehydrogenation of n-butane. Selectivity to C₄ olefin is almost constant in the range of 200–520°C. The apparent activation energy determined between 200 and 360°C was 18.8 kcal/mol, and 9.2 kcal/mol at higher temperatures.

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-. C₄ 200–520°C. 200–360°C 18,8 /, 9,2 /.

     

Magnetic fluorescence and phosphorescence quenching of gas-phase sulfur dioxide

Sulfur dioxide fluorescence and phosphorescence are quenched by a magnetic field. A model is suggested for the qualitative interpretation of the results.

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. , - .

     

Influence of anchored cerium ions on the dispersity and activity of Pd/SiO2 catalysts

(Pd+Ce)/SiO₂ catalysts prepared by decomposition of organometallic complexes of Ce and Pd have higher activity, dispersity and selectivity in methanol synthesis than Pd/SiO₂ catalysts.

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, (Pd+Ce)/SiO₂ , Ce Pd, Pd/SiO₂.