Preparation and thermoanalytic studies of yttrium poly(acrylate)

A new process for the production of advanced ceramic powders has been studied. The process involves the chelation of a metal ion in solution by an organic acid polymer. Using FTIR, TG, DTG and DTA, the process for the formation of the organo-metallic complex and the decomposition to the metal oxide is reported. Effects of packing density on DTA are also discussed.

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Zusammenfassung Ein neues Verfahren zur Herstellung von Keramikpulvern wurde untersucht. Das Verfahren beinhaltet die Chelatisierung eines in Lösung befindlichen Metallions mittels einer polymeren organischen Säure. Unter Zuhilfenahme von FTIR, TG, DTG und DTA wurde der Vorgang der organometallischen Komplexbildung und der Zersetzung zu Metalloxid beschrieben. Der Einfluss der Packungsdichte auf die DTA wird ebenfalls beschrieben.

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, - . - , , , - . .

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The authors would like to acknowledge the BF Goodrich Co. for supplying the polyacrylic acid used in this study. Rong Sheng Zhou is also acknowledged for his assistance using the GRAFIT plotting program.     

Activation energies in catalytic oxidation of benzene

The existence of a linear correlation between the apparent activation energy of benzene disappearance and the primary selectivity was demonstrated for a series of vanadia based catalysts. Analysis of this correlation leads to the conclusion that the activation energies of reaction 1 as well as activation energies of reaction 2 in benzene oxidation scheme do not differ significantly over a series of these catalysts.

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. , 1, 2 .

     

DSC characterization of ZSM-5/MgO/Al2O3 catalysts

The physico-chemical characterization of magnesium-modified ZSM-5 zeolite catalysts has been performed by differential scanning calorimetry. Evidence has been found of the formation of magnesium oxide and the magnesium spinel phase in alumina-bonded ZSM-5 catalysts. DSC proved a suitable technique for characterization of these systems.

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Zusammenfassung Mg-modifizierte ZSM-5-Zeolithkatalysatoren wurden durch DSC charakterisiert. Es wurden Beweise für die Bildung von Magnesiumoxid und Magnesiumspinell in ZSM-5/Aluminiumoxid-Katalysatoren gefunden. DSC hat sich zur Characterisierung dieser Systeme als geeignet erwiesen.

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- 3CM-5, . - - . .

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This work was carried out within the Progetto finalizzato Energetica 2 of the National Research Council of Italy.     

Hydrogenation of ethylene on gadolinium X, Y and L-type zeolites

It is shown that Gd-zeolites have a catalytic activity towards ethylene hydrogenation at 1 atm. This activity decreases with an increase in the SiO₂/Al₂O₃ ratio from 2.2 to 6.1 and 4.1, i.e. upon going from an X type zeolite to Y and L. For these types of zeolite the activity grows with an increase in Gd³⁺ content from 50 to 80%. Oxygen addition to the reaction mixture stabilizes the catalytic activity of zeolites.

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, qv 1 . , SiO₂/Al₂O₃ 2,2 6,1 4,1, .. X Y L. , 50 80%. .

     

Comparative analysis of catalytic properties of 3d metal acetylacetonates in liquid-phase oxidation of dibenzyl ether

Studies of the liquid-phase oxidation of dibenzyl ether in the presence of 12 acetylacetonates of 3d metals and a comparative analysis of the dependence of the catalytic activity and selectivity of chelates on the atomic number and valence state have been carried out.

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12 3d . .

     

Investigation on the thermal behaviour of Mg(NO3)2·6H2O

DTA, DSC and X-ray investigations of Mg(NO₃)₂ · 6H₂O revealed a lattice transformation at (71±2) C withH=12.5 J/g, and congruent melting at 90 C withH=150.3 J/g. The results of the DTA investigations on different Mg(NO₃)₂-H₂O samples are in good agreement with those of solubility investigations. The melting enthalpy of Mg(NO₃)₃ · 6H₂O is lowered considerably by deviation from the stoichiometric water content of the compound. The results allow conclusions as to the application of this salt hydrate as a latent heat-storage material.

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Zusammenfassung DTA-, DSC- und röntgenographische Untersuchungen von Mg(NO₃)₂ · 6H₂O zeigten die Existenz einer Gitterumwandlung bei (71±2) C mitH=12.5 J/g und ein kongruentes Schmelzen bei 90 C mitH=150.3 J/g. Die Ergebnisse der DTA-Untersuchungen an verschiedenen Mg(NO₃)₂-H₂O Proben stehen in guter übereinstimmung mit denen von Löslichkeitsuntersuchungen. Durch ein Abweichen vom stöchiometrischen Wassergehalt der Verbindung wird die Schmelzenthalpie von Mg(NO₃)₂ · 6H₂O beträchtlich vermindert. Die Ergebnisse ermöglichen Aussagen zur Anwendbarkeit dieses Salzhydrates als Wärmespeichermedium.

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, 71±2 H=12,5 · 90 H=150,3 ·^–1. Mg(NO₃)₂-H₂O . . .

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We thank Dr. Flammersheim, Department of Chemistry, FSU, Jena, for the DSC measueements.     

Catalytic hydrogenation of carbon monoxide on RuFe/SiO2 catalysts

The H₂+CO reaction on silica supported Ru, Fe and RuFe catalysts prepared from metal carbonyl clusters has been investigated under atmospheric and 20 bar pressure. According to the change of selectivity values with temperature and with pressure, the participation of surface carbon proposed earlier by several authors seems to be confirmed by this work.

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H₂+CO Ru, Fe RuFe, , 20 . , , , .

     

TPD studies of hydrogen sorption on platinum powder catalysts modified with adsorbed gold

It has been shown that hydrogen determined from the TPD curves of platinum saturated with hydrogen sorbed above room temperature is chiefly absorbed and not adsorbed hydrogen; this absorbed hydrogen has no effect on the charging curve.

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, , , , ; .

     

Effect of alkaline additives on the C?O bond dissociation of adsorbed CO in methanation over Ru/Al2O3 catalyst

ESR studies of the thermal stability of anion radicals O^– on the MgO surface have revealed that most stable (at T>420 K) are O^– with g ²=2.032 and g ³=2.044, whereas anion radicals with g ¹=2.042 are destroyed at T<400 K and possess the highest heat of [O^–·O₂] complex formation.

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- O^– MgO. , O^– g ²=2.032 g ³=2.044, 420 , O^– g ¹=2.042 400 . , [O^–·O₂] - O^– g ¹=2.042.