Ammoxidation of 3- and 4-picolines over V2O5?SnO2/γ?Al2O3 catalyst

The ammoxidation of 3- and 4-picolines has been studied over V₂O₅–SnO₂/–Al₂O₃ catalysts prepared by surface impregnation technique. Best results were obtained for the generation of cyanopyridines in the temperature range 400–450°C and sub-stoichiometric value with respect to O₂. Catalysts that were calcined above 700°C showed no activity.

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3- 4- V₂O₅–SnO₂/–Al₂O₃, . 400–450°C O₂. , 700 K, .

     

Potential for coal calorific value corrections,dependent on the carbonate mineral type present

In addition to calcite, other carbonate minerals in coal all undergo endothermic reactions on heating, i.e. dolomite, ankerite, siderite, aragonite, magnesite, rhodochrosite, witherite and strontianite. Of these, when determined in air, siderite and rhodochrosite give small exothermic resultants, while the amount of Fe in ankerites affects the actual endothermic values obtained. The magnitude of these carbonate decomposition reactions can be shown by DTA to be different and will need to be allowed for individually in calorific value corrections of coals containing them.

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Zusammenfassung Nicht nur Kalkspat, sondern auch andere in Kohle vorkommende Karbonatmineralien wie z. B. Dolomit, Ankerit, Spateisenstein, Aragonit, Magnesit, roter Braunstein, Witherit und Strontionit gehen bei Erhitzen endothermische Reaktionen ein. Von diesen zeigen Spateisenstein und roter Braunstein exotherme Ergebnisse kleinen Wertes, während der Betrag an Eisengehalt in Ankeriten den jeweils gemessenen endothermischen Wert beeinflußt. Das Ausmaß dieser Karbonatzersetzungsreaktionen kann durch DTA-Messungen als unterschiedlich nachgewiesen werden und muß bei den Kaloriewertkorrektionen für Kohlen, die diese Mineralien enthalten, berücksichtigt werden.

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, , , , , , , , . , , . , , .

     

Thermoanalytical investigations of some industrial wastes produced in steel works

The experiments involves three types of industrial wastes produced by iron works, which create serious hazards to the natural environment: (1) paint-shop sludge, (2) oil-polluted diatomite, and (3) oil-polluted scale. The choice of an appropriate and safe storage method should be based on extensive physicochemical examination.DTA, in combination with other data, allows characterization of the combustible properties of wastes. Thermoanalytical measurements were carried out in a dynamic air atmosphere. Enthalpy values were calculated from peak areas of DTA curves. Thermoanalytical data were compared with calorimetric results obtained with an oxygen bomb.

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Zusammenfassung Drei Arten industrieller Abtälle eines Stahlwerks, die schwere Umweltbelastungen darstellen, wurden untersucht: (1) Lackiererei-Schlamm, (2) ölhaltiger Diatomit, (3) ölhaltiger Kesselstein. Geeignete sichere Deponien setzen ausführliche physikalisch-chemische Untersuchungen voraus. DTA in Kombination mit anderen Untersuchungen erlaubt die Charakterisierung der Verbrennungseigenschaften der Abfälle. Die thermoanalytischen Untersuchungen erfolgten im Luftstrom, die Verbrennungswärmen wurden aus den DTA-peak-Flächen berechnet. Die Ergebnisse werden mit denen kalorimetrischer Messungen in einer Sauerstoffbombe verglichen.

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- , . , . , - . . . . , .

     

Kinetics of aluminium hydroxide dehydration

Non-isothermal thermogravimetric analysis was used for determination of the kinetics of aluminium hydroxide dehydration in an air atmosphere and for processing of the experimental results by the method due to Chatterjee.Aluminium hydroxide dehydration proceeds according to the following mechanism: Al(OH)₃AlOOH + H₂O 2 AlOOHAl₂O₃ + H₂OBoth reactions proceed in the diffusion region, the first up to 526 K and the second up to 700 K, and the corresponding activation energy values are 15.7 and 0.2 kJ/mole, respectively.

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Zusammenfassung Die nicht-isotherme thermogravimetrische Analyse wurde zur Bestimmung der Kinetik der Dehydration von Aluminiumhydroxid in Luft-Atmosphäre eingesetzt und die Methode von P. K. Chatterjee zur Verarbeitung der Versuchsergebnisse angewendet.Der Dehydratisierungsvorgang von Aluminiumhydroxid verläuft nach folgendem Mechanismus: Al(OH)₃AlOOH + H₂O 2 AlOOHAl₂O₃ + H₂OBeide Reaktionen spielen sich in der Diffusionszone ab, die erstere bis zur Temperatur von 526 K und die zweite bis zur Temperatur von 700 K. Die entsprechenden Aktivierungsenergien sind 15.70 kJ/Mol für die erste und 0.20 kJ/Mol für die zweite Reaktion.Bei kontinuierlicher Erhöhung der Temperatur über 526 K im ersten und über 700 K im zweiten Fall werden die Geschwindigkeiten dieser Reaktionen durch kristallchemische Umwandlungen begrenzt und die Aktivierungsenergie beträgt 116.97 kJ/Mol für die erste und 91.92 kJ/Mol für die zweite Reaktion.

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Résumé On détermine la cinétique de la déshydratation de l'hydroxyde d'aluminium dans l'air, par thermogravimétrie non-isotherme, en dépouillant les résultats suivant la méthode proposée par P. K. Chatterjee.Le processus de la déshydratation de l'hydroxyde d'aluminium s'effectue suivant le mécanisme: Al(OH)₃AlOOH + H₂O 2AlOOHAl₂O₃ + H₂OLes deux réactions ont lieu par diffusion, la première jusqu'à la température de 526 K et la seconde jusqu'à 700 K, les valeurs correspondantes des énergies d'activation étant 15.70 kJ · mol^–1 pour la première et 0.20 kJ · mol^–1 pour la seconde réaction.Lors d'une élévation continue de la température au-dessus de 526 K dans le premier cas et au-dessus de 700 K dans le deuxième cas, les vitesses de ces réactions deviennent limitées en raison des transformations cristallochimiques et les valeurs des énergies d'activation sont 116.97 pour la première et 91.92 kJ · mol^–1 pour la seconde réaction.

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, — . : Al(OH)₃AlOOH + H₂O 2 AlOOHAl₂O₃ + H₂O , 526 , — 700 . 15,70 0,20 / . 526 700 — , - , , 116,97 91,92 /.

     

Calculation of the energy spectrum of surface oxygen on CuO by the interacting bonds method

Using the interacting bonds model a calculation has been made for the energy spectrum of oxygen on the CuO surface. Dissociative adsorption of oxygen can be realized in one and two-center forms with 9.2 and 60.4 kcal/mol, respectively. Intermediate values of the adsorption heats are attributed to oxygen adsorption on induced and biographic defects. The theoretically calculated energy spectrum of adsorbed oxygen is in reasonable agreement with that obtained experimentally from the dependence of isosteric heats of oxygen adsorption on the surface coverage.

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CuO. - 9,2 60,4 / . . .

     

Kinetics of the oxidation of oxalic acid by cerium(IV) sulfate in dilute sulfuric acid

The kinetics of the oxidation of oxalic acid by cerium(IV) in sulfuric acid medium has been studied voltammetrically. The specific reaction rate is 132±4.0 M^–1s^–1 at 25.0 °C. The energy of activation is 62.6±3.0 kJ mol^–1. The entropy of activation is –2.7 J mol^–1K^–1. The specific reaction rate is influenced by complexation and also by ionic strength (). The most likely mechanism has been suggested.

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(IV) . 132±4,0 M^–1c^–1 25,0 °C. 62,6±3,0 ·M^–1. –2,7 ·K^–1M^–1. , (). .

     

Spectroscopic studies of the state of Cu2+ ions in Cu?Zn?Al oxide catalysts

ESR and electronic spectroscopy have reveled that in low-temperature ZnO the copper ions form Cu–O–Cu type cluster structures with highly covalent bonds and strong exchange interaction between the ions. The nearer environment of the Cu²⁺ ions is an octahedron with distortion towards square planar coordination.

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, ZnO Cu–O–Cu . Cu²⁺- , .

     

Tripenoid glycosides of alfalfa. VII. Medicosides E and F

Two hederagenin glycosides — medicosides E and F — have been isolated from the roots ofMedicago sativa L. (Leguminosae). Medicoside E has the structure of hederagenin 28-O--D-glucopyranoside 3-O-[O--G-glucopyranosyl-(13)--D-xylopyranoside]. Medicoside F has the structure of hederagenin 28-O--D-glucopyranoside 3-O-[O--D-glucopyranosyl-(12)--L-arabinopyranoside].Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Institute of Organic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii. No. 5, pp. 701–705, September–October, 1993.     

Ausbrennen von Kohlenstoffhaltigen,in den Ziegelrohstoff Eingepressten Stoffen

Zusammenfassung Die Kinetik der Ausbrennung organischer Stoffe im Ziegelscherben wird verfolgt und erläutert. Die Möglichkeiten der Beeinflussung des energetischen Aufwandes unter Nutzung moderner analytischer Methoden sind festzustellen. Bei einem diffusen Ausbrennen ist die Dichte und Durchlässigkeit des Scherbens massgebend. Praktische Anwendungsmöglichkeiten verschiedener auszubrennender Stoffe in unterschiedlichen Rohstoffen der Ziegelindustrie.

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The kinetics of burn-out of organic materials in bricks has been followed and explained. It is to establish that using new analytical methods the energy consumption can be influenced. The diffuse burn-out is determined by the density and permeability of bricks. There is a possibility for practical use of the results in the brick-industry with the different compounds to be burnt out from various raw materials.

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$ . , . . .

     

IR investigation of phenol methylation on MgO

The adsorption of phenol, anisole, o-cresol and methanol on MgO was studied by infrared spectroscopy. The surface species of phenol, anisole and o-cresol were of the phenolate type and for methanol of the methoxide type.

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, , - MgO . , - , — .

     

A Thermal study of the precipitates formed in ammonia neutralization of acidic solutions of dissolved phlogopite

The precipitates containing mainly iron, aluminium and magnesium hydroxides, obtained from phlogopite dissolved in nitric acid by means of the neutralization procedure with ammonia, have been investigated by thermal analysis (TG, DTG and DTA). According to the present study, which is part of a larger investigation into the chemical utilization of Finnish mica minerals, the formation of solid solutions between iron and aluminium hydroxides in silt increases with an increasing neutralization temperature. Nitrogen exists mainly in the form of nitrate in silts, and magnesium forms mixed hydroxides with aluminium, which causes a separation between the iron hydroxide and magnesium aluminium hydroxide phases.

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Zusammenfassung Die von in Salpetersäure gelöstem Phlogopit durch Neutralisierung mit Ammoniak erhaltenen, hauptsächlich Eisen-, Aluminium- und Magnesiumhydroxid enthaltenden Niederschläge wurden thermoanalytisch (TG, DTG und DTA) untersucht. In der vorliegenden Arbeit, die Teil einer grossangelegten Untersuchung zur chemischen Nutzung finnischer Glimmermineralien ist, wird gezeigt, dass die Bildung fester Lösungen von Eisen- und Aluminiumhydroxiden in Schluff mit zunehmender Neutralisationstemperatur ansteigt. Stickstoff kommt in Schluff hauptsächlich in Form von Nitraten vor, und Magnesium bildet Mischhydroxide mit Aluminium, was eine Trennung der Eisenhydroxidphase von der Magnesium-Aluminium-Hydroxidphase bewirkt.

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, , , . . , , . , , , , .

     

Conversion of C1?C2 alkanes over manganese catalysts reoxidized by carbon dioxide and oxygen

Reoxidation of Mn-containing catalysts by oxygen and carbon dioxide in the conversion of C₁–C₂ alkanes has been studied. Reoxidation of these catalysts by carbon dioxide and oxygen added at a certain ratio permits to obtain optimum degree of surface oxidation, ensuring the high selectivity of conversion of C₁–C₂ alkanes to C₂H₄.

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Mn- C₁–C₂. , Mn- , C₁–C₂ C₂H₄.

     

Temperature programmed desorption (TPD) of carbon monoxide from cobalt surfaces

Three different binding states of CO on cobalt surfaces have been identified by TPD studies. The energetics of these adsorption states and their relevance in Fischer-Tropsch synthesis are considered.

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CO - . -.

     

Synthesis and study of some 4-substituted 2-(benzimidazol-2′-yl)quinolines

The reaction of 4-chloro- and 4-chloro-6-methoxyquinoline-2-carbaldehydes with ophenylenediamine has given the corresponding 4-chloro-2-(benzimidazol-2-yl)quinolines. 4-Methoxy-, 4-diethylamino-, 4-cyclohexylamino-, and 11 different 4-anilino-substituted 2-(2-benzimidazol-2-yl)quinolines have been synthesized from these by replacement of the halogen. A study of their UV spectra has shown that absorption at 310 nm is characteristic for the 4-anilino-2-(benzimidazol-2-yl)quinolines but not for the other 4-substituted derivatives. The compounds obtained form colored complexes with cuprous ions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 835–837, June, 1970.     

Methanol conversion to hydrocarbons and dimethyl ether on decationized zeolite T

Methanol transformations over the hydrogen forms of zeolite T (32%–76% decationization and 13%–32% dealumination) during contact with methanol vapor was studied at 200°–400°C. The catalysts used show a high activity in methanol conversion into light hydrocarbons and dimethyl ether but over a short period.

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T (32–16% 13–32% ) 200–400°C. , .

     

Steroid glycosides from the starfish Crossaster papposus

Two new steroid glycosides have been isolated from an ethanolic extract of the starfishCrossaster papposus — crossasterosides P₁ and P₂. On the basis of chemical transformations and spectral characteristics, the structure of crossasteroside P₁ has been established as (24R)-24-ethyl-5-cholestane-3,6,8,15,16,29-hexaol 29-O-[2-O-methyl--D-xylopyranosyl-(1 2)--D-galactofuranoside]. Crossasteroside P₂ is its 4-hydroxy analogue.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 669–673, September–October, 1989.     

Effect of calcination temperature on the surface composition of Mo?Fe catalysts for methanol oxidation

XPS studies have revealed a decrease in the concentration of iron atoms on the surface of Mo–Fe catalysts with increasing calcination temperature. From a comparison of chemical analysis and XPS data the Mo/Fe ratios on the surface of catalyst samples at various calcination temperatures have been determined. Comparing the above data with changes in the catalytic activity of the samples examined in methanol oxidation, the conclusion has been made that the active component of the catalysts is a solid solution of molybdenum oxide in ferric molybdate.

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. Mo/Fe . , .

     

Stereochemistry of heterogeneous catalytic reactions; epimerization of alicyclic diols on copper catalysts

During the reactions of 8 isomeric alicyclic diols on Cu/Al and Cu catalysts, epimerization of the isomers was observed. The epimerization proceeds via a hydroxy-oxo intermediate.

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8 Cu/Al Cu . -.

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Part XLII of the series Study of the transformations of diols and cyclic ethers.     

Thermal stability of poly(β-bromostyrene) and copolymers of β-bromostyrene with methyl methacrylate

The thermal stabilities of poly(-bromostyrene), poly-(methyl methacrylate) homopolymers and copolymers of-bromostyrene-methyl methacrylate covering the entire composition range were studied using TG analysis. At each extreme of the composition range, incorporation of comonomer units results in a copolymer more stable than the brominated homopolymer. Maximum stability occurs for compositions of approximately 62 mole percent-bromostyrene. The formation of the anhydride structure among the degradation products leads to the stability of the copolymers.

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Zusammenfassung Die thermische Stabilität von-Bromstyrol- und Methylmethacrylat-Homopolymeren sowie von sich über den ganzen Zusammensetzungsbereich erstreckenden-Bromstyrol/Methylmethacrylat-Kopolymeren wurde thermogravimetrisch untersucht. An beiden Enden des Zusammensetzungsbereichs führt der Einbau von Komonomereinheiten zu einem Kopolymer, das stabiler als das bromierte Homopolymer ist. Maximale Stabilität wird bei einem Gehalt von etwa 62 Mol-%-Bromstyrol erreicht. Die Bildung der Anhydridstruktur führt zur Stabilität des Kopolymers.

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/-, - . , . - 62%. .

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Presented at the World Conference of Thermal Analysis, held in Bad Hofgastein (Austria), 1985.