The mercury (63P1) photosensitized hydrogenation of ethylene. Kinetics of the reaction C2H5 + H2 = C2H6 + H

1968 ◽  
Vol 46 (20) ◽  
pp. 3275-3281 ◽  
Author(s):  
L. E. Reid ◽  
D. J. Le Roy
Keyword(s):  
Gas Phase ◽  
Molecular Hydrogen ◽  
Mercury Vapor ◽  
Experimental Conditions ◽  
Working Pressure ◽  
Extinction Coefficients ◽  
Secondary Reactions ◽  
Ethyl Radicals ◽  
Kinetics Of ◽  
Hydrogenation Of Ethylene

A quantitative study has been made of the reaction of ethyl radicals with molecular hydrogen in the gas phase in the temperature range 240 to 320 °C. The mercury (63Pi) photosensitized decomposition of hydrogen in the presence of ethylene was used to generate ethyl radicals. Extinction coefficients for the absorption of 2537 Å by mercury vapor were measured and Beer's law was shown to be obeyed under the experimental conditions used. The corrections required to allow for the nonuniformity of radical concentrations in the cell were small. After delineating the experimental conditions necessary to minimize secondary reactions, the rate constant (cm3 mole−1 s−1) for the reaction C2H5 + H2 = C2H6 + H was found to be given by log10k = 12.57 − 13.7/θ. Experiments in the presence of added carbon dioxide showed the absence of hot radical effects at the working pressure of 92 Torr of hydrogen.

Simultaneous photochemical generation of ozone in the gas phase and photolysis of aqueous reaction systems using one VUV light source

1997 ◽  
Vol 35 (4) ◽  
pp. 41-48 ◽  
Author(s):  
T.M. Hashem ◽  
M. Zirlewagen ◽  
A. M. Braun
Keyword(s):  
Gas Phase ◽  
Light Source ◽  
Organic Pollutants ◽  
Vacuum Ultraviolet ◽  
Oxidative Degradation ◽  
Reaction System ◽  
Photochemical Reactions ◽  
Experimental Conditions ◽  
Photochemical Generation ◽  
Kinetics Of

A more efficient use of vacuum ultraviolet (VUV) radiation produced by an immersed Xe-excimer light source (172 nm) was investigated for the oxidative degradation of organic pollutants in aqueous systems. All emitted VUV radiation from one light source was used in two simultaneous but separate photochemical reactions: (1) photochemical generation of ozone by irradiating oxygen in the gas phase and (2) photolysis of the aqueous reaction system. The gas stream containing the generated ozone is sparged into the reaction system, thus enhancing the oxidative degradation of organic pollutants. The photochemically generated ozone in the gas phase was quantitatively analyzed, and the kinetics of the degradation of 4-chlorophenol (4-CP) and of the dissolved organic carbon (DOC) were determined under different experimental conditions. The results show that the rates of degradation of the substrate and of the DOC decrease in the order of the applied processes, VUV/O3 > O3 > VUV.

The kinetics of gas phase reactions studied in a "homogeneous reactor"

1988 ◽  
Vol 66 (9) ◽  
pp. 2325-2334 ◽  
Author(s):  
John M. Roscoe
Keyword(s):  
Gas Phase ◽  
Kinetic Studies ◽  
Gas Phase Reactions ◽  
Reaction Volume ◽  
First Order ◽  
Homogeneity Assumption ◽  
Good Spatial Resolution ◽  
Secondary Reactions ◽  
Homogeneous Reactor ◽  
Kinetics Of

The use of a "well-stirred" or "homogeneous" reactor in kinetic studies of gas phase reactions has been examined to assess the sensitivity of the method to the criteria upon which its use is based. The effects of heterogeneous and homogeneous secondary reactions are considered and the validity of the assumption of homogeneity has been examined experimentally for conditions similar to those which have been used elsewhere. The atom sink presented by the excess reagent under pseudo first order conditions results in failure of the homogeneity assumption. However, it is found that homogeneity is not required for successful use of the method provided the analytical measurements have good spatial resolution and the reaction volume is well-defined. The method is illustrated by using it to study some reactions of O(3P).

Kinetics of the Fully Inhibited Thermal Decomposition of Bistrifluoromethyl Peroxide, CF3OOCF3

1975 ◽  
Vol 53 (10) ◽  
pp. 1442-1448 ◽  
Author(s):  
Bernard Descamps ◽  
Wendell Forst
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Chromatographic Analysis ◽  
Static Method ◽  
Experimental Conditions ◽  
Experimental Expression ◽  
Kinetics Of ◽  
Rate Of Accumulation

The pyrolyosis of CF3OOCF3 (BTMP) was studied in the gas phase from 5 to 100 Torr BTMP pressure and between 197 and 244 °C in a clean nickel reactor by the static method. CF3O radicals, due to the initial split[Formula: see text] were scavenged by SO3F radicals produced in situ by the thermal decomposition of their dimer S2O6F2. Under these conditions, CF3OOSO2F is the only product of BTMP pyrolysis, as shown by gas chromatographic analysis. Thus the BTMP pyrolysis becomes fully inhibited and the rate of accumulation of CF3OOSO2F is a measure of k1. The rate constant k1 turns out to be pressure-insensitive under the experimental conditions, from which it is inferred that k1 is actually k1∞, the limiting high-pressure unimolecular rate constant for reaction 1. Its temperature dependence yields the result[Formula: see text]This result is compared with other values of the O—O bond dissociation energy in BTMP. The experimental expression for k1 ∞ is used to construct the pressure falloff of k1 following the procedure of Forst. The calculation confirms that falloff begins only below 10 Torr.

PHOTOLYSIS OF DIETHYL KETONE AT LOW PRESSURES: THE PRESSURE DEPENDENCY OF THE COMBINATION OF ETHYL RADICALS

1955 ◽  
Vol 33 (12) ◽  
pp. 1840-1852 ◽  
Author(s):  
R. K. Brinton ◽  
E. W. R. Steacie
Keyword(s):  
High Light Intensity ◽  
Methyl Radicals ◽  
Reaction Intermediates ◽  
Experimental Conditions ◽  
Diethyl Ketone ◽  
Pressure Dependency ◽  
Pressure Independent ◽  
Low Pressures ◽  
Ethyl Radicals ◽  
Kinetics Of

The photolysis of diethyl ketone has been investigated in the pressure range 0.01–30 mm. at 100°, 150°, 200°, and 250° with a variation in absorbed intensity of 1000-fold. Over this wide variation in experimental conditions the kinetics of the reaction show excellent agreement with the mechanism of Kutschke, Wijnen, and Steacie. Under conditions where the production of ethylene by decomposition of the pentanonyl radical was negligible (high light intensity and low ketone pressure), the ratio of the rate of ethylene formed to the rate of butane produced was determined to be 0.12 independent of the temperature. These data indicate that both the disproportionation and combination of ethyl radicals are homogeneous and pressure independent to as low as 0.01 mm. pressure. In addition it is probable that the two reactions are the result of different reaction intermediates as was postulated by Wijnen and Steacie. The abstraction reactionC2H5+C2H5COC2H5 → C2H6+C2H4COC2H5showed definite heterogeneous character at low pressures similar to the analogous reaction of methyl radicals with acetone studied by Ausloos and Steacie.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

scholarly journals 18.1% single palladium atom catalysts on mesoporous covalent organic framework for gas phase hydrogenation of ethylene

2021 ◽  
Vol 2 (7) ◽  
pp. 100495
Author(s):  
Chun-Te Kuo ◽  
Yubing Lu ◽  
Pezhman Arab ◽  
K. Shamara Weeraratne ◽  
Hani El-Kaderi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Palladium Atom ◽  
Covalent Organic Framework ◽  
Hydrogenation Of Ethylene ◽  
Organic Framework
Sign in / Sign up

Export Citation Format

Share Document