Search results for "Oxide"

Über die zersetzung von hydroperoxyden durch katalase und durch lebereiweißfraktionen

1959

Es werden Herstellung und Eigenschaften einer Eiweisfraktion aus Rinderleber beschrieben, die auf Wasserstoffperoxyd, athyl-, Isopropyl- und tert.-Butylhydroperoxyd zersetzende Wirkung ausubt. Der fur das Zustandekommen der Zersetzungsreaktion der drei letzgenannten Peroxyde notwendige Acceptor wird als athanol identifiziert. Die Eiweisfraktion wird bezuglich ihrer Eigenschaften mit einer kristallisierten Katalase verglichen und aus dem Ergebnis der Schlus gezogen, das sie mit Katalase identisch ist. Als Reaktionsprodukt der enzymatisch katalysierten Reaktion zwischen tert.-Butylhydroperoxyd und athanol wurde Acetaldehyd nachgewiesen. The preparation and properties of an albumen fraction fr…

The use of topological models in analytical chemistry

2005

In the present paper, the possible analytical applications of two toplogical models, the DARC model and the group contribution model, are discussed. Both models are applied to obtain calibration laws, which relate UV and IR characteristics with the chemical structure of ethylene oxide condensates. The group contribution model is also applied to determine the contribution of each part of the different compounds involved in a chemical interaction process, having established the sensitization parameters of benzodiazepines and anionic surfactants from the micellar enhancement fluorescence.

Fluorimetric determination of binding constants between micelles and chemical systems

1991

Abstract A fluorimetric method is adapted to determine the binding constants (K) between different systems and micelles. The method is based on the variation of the fluorescence of the system in the presence of increasing amounts of a surfactant agent. This method permits the determination of binding constants in strong acid or alkaline media. The binding constants of 1-naphthol and 2-(4-alkylamino-2 hydroxyphenyl)benzo-X azoles (X being an O or an S atom, PAS-O and PAS-S) with cationic, anionic, and nonionic surfactants have been determined by the proposed method. Values from 49,100 M−1 for the interaction between PAS-S and CTAB in basic medium to 10 M−1 for the interaction of 1-naphthol w…

Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxide catalysts

2004

Abstract MoVTeNbO catalysts, prepared by hydrothermal synthesis, are active and highly selective in the ODH of ethane, especially those with a MoVTeNb molar ratio of 1–0.15–0.16–0.17 and heat-treated at 600–650 °C. On the best catalyst, selectivities higher than 80% at ethane conversion levels higher than 80% have been obtained operating at relatively low reaction temperatures (340–400 °C). Thus, yields of ethylene of ca. 75% have been obtained, which exceeds the best yield reported in the literature. Te 2 M 20 O 57 ( M =Mo, V, Nb) and (V,Nb)-substituted θ -Mo 5 O 14 , in addition to small amounts of the Te 0.33 M O 3.33 ( M =Mo, V, Nb) phase, can be proposed in the most selective cataly…

Spectroscopic and chromatographic study of the interaction of nonionic micelles with the aluminum-morin complex

1989

Abstract The interaction of the aluminum-morin system with different nonionic surfactants has been studied spectrophotometrically and by high-performance liquid chromatography. It has been found that ethylene oxide-propylene oxide condensate surfactants sensitize the spectrophotometric determination of aluminum with morin more than ethylene oxide condensate surfactants. Binding ratio parameters for the different surfactants with free morin have been also estimated from the analysis of chromatographic vacant peaks.

On the electrochemical reduction of carbon dioxide and ethylene

1973

Die gemeinsame Elektrolyse von Athylen (I) und Kohlendioxid (II) liefert je nach den angewandten Bedingungen Mischungen aus Oxalsaure (III) und Bemsteinsaure (IV).

ChemInform Abstract: Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

2016

Above 31.1 °C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO2) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO2 is presented.

Selective oxidation of propane and ethane on diluted Mo–V–Nb–Te mixed-oxide catalysts

2007

Abstract Te-free and Te-containing Mo–V–Nb mixed oxide catalysts were diluted with several metal oxides (SiO 2 , γ -Al 2 O 3 , α -Al 2 O 3 , Nb 2 O 5 , or ZrO 2 ), characterized, and tested in the oxidation of ethane and propane. Bulk and diluted Mo–V–Nb–Te catalysts exhibited high selectivity to ethylene (up to 96%) at ethane conversions 10 % , whereas the corresponding Te-free catalysts exhibited lower selectivity to ethylene. The selectivity to ethylene decreased with the ethane conversion, with this effect depending strongly on the diluter and the catalyst composition. For propane oxidation, the presence of diluter exerted a negative effect on catalytic performance (decreasing the forma…

Carbon Dioxide as Chemical Feedstock. Edited by Michele Aresta.

2010

On the occurrence of ClO in cirrus clouds and volcanic aerosol in the tropopause region

1997

Airborne observations during descents of the ER-2 through layers of volcanic aerosol (Mount Pinatubo eruption of 1991) and a cirrus cloud are utilized to study the the abundance of ClO and its relation to aerosol surface area in the midlatitude tropopause region. During a cirrus event near the tropopause ClO mixing ratios up to 2.7 pptv were detected and near the tropopause ClO levels from a few to 70 pptv were found. These measurements are associated with large experimental uncertainties but demonstrate the possible presence of ClO inside cirrus clouds and near the tropopause. Model calculations show that possible enhancements of ClO by heterogeneous chemistry on cirrus cloud particles cou…