A kinetic and surface study of the oxidation of ethane by nitrous oxide and by oxygen over manganese(III) oxide

1982 ◽  
Vol 60 (7) ◽  
pp. 893-897 ◽  
Author(s):  
Craig Fairbridge ◽  
Robert Anderson Ross
Keyword(s):  
Nitrous Oxide ◽  
Infrared Spectroscopy ◽  
Catalyst Surface ◽  
Binding Energies ◽  
Adsorbed Species ◽  
X Ray ◽  
Chemisorbed Oxygen ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Oxygen Complexes

The kinetics of the nitrous oxide/ethane and oxygen/ethane reactions on manganese(III) oxide have been studied from 573 to 673 K and from 523 to 593 K, respectively. The apparent activation energy for carbon dioxide formation was 130 ± 4 kJ mol−1 in both reactions while that for nitrogen formation in the nitrous oxide/ethane reaction changed from 106 ± 4 kJ mol−1, 573–613 K, to 133 ± 4 kJ mol−, 623–673 K. The kinetic results for both reactions fit the same rate equation:[Formula: see text]where px represents either [Formula: see text]. The rate-controlling step has been associated with the interaction of adsorbed species on the catalyst surface while both ethane and the oxidising gas appear to be directly involved in further steps in the mechanism. Samples were analysed routinely by scanning electron microscopy, X-ray powder diffraction, and infrared spectroscopy. Electron spectroscopy results from samples treated in various ways with hydrocarbon/oxidant mixtures gave O(1s) values from 528.7 to 529.7 eV which are indicative of binding energies usually associated with chemisorbed oxygen. No N(1s) spectrum was obtained from catalysts exposed to hydrocarbon/nitrous oxide mixtures, in agreement with the absence of bands in the infrared which are usually associated with nitrates or nitrogen/oxygen complexes. A binding energy value of 406.5 eV was measured in the comparable N(1s) spectrum of a catalyst used at 623 K for the oxidation of ethane by nitric oxide — a result which confirms conclusions from previous surface studies on the same system using infrared spectroscopy.

Kinetics of the oxidation of ethane and 1-butene over manganese oxide supported on carbon fibres

1982 ◽  
Vol 60 (21) ◽  
pp. 2749-2754 ◽  
Author(s):  
Craig Fairbridge ◽  
James R. MacCallum ◽  
Robert A. Ross
Keyword(s):  
Manganese Oxide ◽  
Photoelectron Spectroscopy ◽  
Adsorbed Species ◽  
Catalyst Structure ◽  
X Ray ◽  
Hydrocarbon Gas ◽  
Apparent Activation Energies ◽  
Products Of Reaction ◽  
Kinetics Of ◽  
Krypton Adsorption

The oxygen/ethane and oxygen/1-butene reactions have been investigated in a continuous flow system at atmospheric pressure over a manganese oxide/carbon fibre catalyst. The products of reaction were carbon dioxide and water. Apparent activation energies were 108 ± 4 kJ mol−1for the former reaction from 673 to 573 K, and 81 ± 4 kJ mol−1 for the latter from 573 to 473 K. Kinetic data for both reactions were best described by the rate equation:[Formula: see text]The surface mechanism may be complex and it is proposed that reactants interact as adsorbed species each of which is adsorbed on two surface sites. Both oxygen and the hydrocarbon gas appear to be directly involved in further steps. Scanning electron microscopy, X-ray photoelectron spectroscopy, and low temperature krypton adsorption were used to assess the catalyst structure.

scholarly journals Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies

2020 ◽  
Vol 22 (34) ◽  
pp. 18806-18814
Author(s):  
Baran Eren ◽  
Christopher G. Sole ◽  
Jesús S. Lacasa ◽  
David Grinter ◽  
Federica Venturini ◽  
...  
Keyword(s):  
Water Vapour ◽  
Catalyst Surface ◽  
Ambient Pressure ◽  
Methanol Conversion ◽  
Chemical State ◽  
Adsorbed Species ◽  
X Ray ◽  
Cu Catalyst

A model Cu catalyst surface oxidises to Cu2O when methanol, oxygen and water vapour are all present during methanol conversion.

Kinetics of the oxidation of ethane by nitric oxide over manganese(III) oxide

1981 ◽  
Vol 59 (14) ◽  
pp. 2232-2238
Author(s):  
R. A. Ross ◽  
C. Fairbridge
Keyword(s):  
Nitric Oxide ◽  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Atmospheric Pressure ◽  
Flow System ◽  
Oxide Formation ◽  
Catalyst Structure ◽  
X Ray ◽  
Apparent Activation Energies ◽  
Kinetics Of

The catalytic reaction between ethane and nitric oxide over manganese(III) oxide has been investigated in a continuous flow system from 673 to 573 K at atmospheric pressure. The products of catalysis were nitrogen, carbon dioxide, nitrous oxide, and water. The rate of nitrous oxide formation was constant over this temperature region, while the apparent activation energies for nitrogen and carbon dioxide formation increased from 32 ± 4 and 22 ± 4 kJ mol−1, respectively, at 573 to 613 K, to 78 ± 4 and 63 ± 4 kJ mol−1 between 613 and 673 K. The kinetic results were best described by the rate equation:[Formula: see text]The surface mechanism appears to be complex and has been interpreted by a scheme involving interaction of the reactants in an absorbed layer. Both nitric oxide and ethane are believed to be involved further in subsequent steps. Infrared evidence indicates the possibility of a surface nitrate intermediate consistent with the mechanistic proposal. Scanning electron microscopy and X-ray powder diffraction techniques were used to assess the catalyst structure.

scholarly journals Applications of Sxps for Studying Surface Structure, Reaction Mechanisms and Kinetics

1994 ◽  
Vol 375 ◽  
Author(s):  
D. R. Mullins ◽  
D. R. Huntley ◽  
S. H. Overbury
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Surface Adsorption ◽  
Binding Energies ◽  
Adsorption Site ◽  
Reaction Intermediates ◽  
Adsorbed Species ◽  
X Ray ◽  
Relative Binding ◽  
Initial Coverage

AbstractSoft x-ray photoelectron spectroscopy (SXPS) from the S 2p core level has been used to study adsorbate induced reconstruction, identify reaction intermediates and study reaction kinetics on the Ni(111) surface. The S 2p binding energy is affected by the nature of the surface adsorption site. It has been determined from the number of S 2p states and their relative binding energies that adsorbed S induces a reconstruction of the Ni(111) surface and that the S adsorbs in fourfold sites on terraces and in troughs. S 2p SXPS has also been used to identify adsorbed species during the thermal decomposition of methanethiol on Ni(111). CH3SH adsorbs as CH 3S- at low temperatures. Above 200 K, the CH3S- changes adsorption site and the C-S bond begins to cleave. The relative concentrations of CH3S- in the two different sites and of atomic S have been monitored as a function of temperature and initial coverage. As a result of the sensitivity and resolution available in SXPS, reactions rates and kinetic parameters have been obtained for the decomposition of benzenethiol on Ni(111) by monitoring the changes in the surface composition continuously as a function of temperature and time.

Study of factors controlling the sorption of diclofenac on a calcined synthetic hydrotalciteÉtude des facteurs contrôlant la sorption du diclofénac sur une hydrotalcite de synthèse calcinée

2013 ◽  
Vol 48 (3) ◽  
pp. 294-304
Author(s):  
Rachid Khatem ◽  
Abdellah Bakhti
Keyword(s):  
Infrared Spectroscopy ◽  
Sorption Capacity ◽  
Sorption Process ◽  
X Ray Diffraction ◽  
Order Model ◽  
X Ray ◽  
Calcined Hydrotalcite ◽  
Constant Ph ◽  
Kinetics Of ◽  
Kinetics Of Sorption

The removal of diclofenac by sorption on a synthetic hydrotalcite and on its calcined product was investigated. The solid [Mg-Al-CO3], prepared by coprecipitation at constant pH, was characterized by X-ray diffraction and infrared spectroscopy (FTIR). The interaction of these materials with diclofenac shows that the kinetics of sorption is fast and follows the second order model. The effects on the sorption process of the diclofenac concentration in the solution, the sorbent concentration and the temperature were studied. The treatment of solutions containing from 0.02 to 2 mmole L−1 of diclofenac produced good results. The sorption capacity of the calcined hydrotalcite is close to 1.9 mmole g−1. The study of the reversibility of the sorption of diclofenac shows that the recycling of these calcined materials is possible, thus suggesting their possible use as supports for the removal of diclofenac. Recycling by restitution and calcination-rebuilding should make possible the recovery of this pollutant.

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

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