Oxydation lente du cétène en phase gazeuse. I. Réaction à "hautes températures"

1971 ◽  
Vol 49 (2) ◽  
pp. 294-302 ◽  
Author(s):  
Pierre Michaud ◽  
Cyrias Ouellet
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Static Method ◽  
Chain Reaction ◽  
Slow Combustion ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
A Chain ◽  
Two Temperature

The slow combustion of ketene in the gas phase was studied by the static method in a 30 × 4 cm Vycor cylinder between 280 and 500 °C at pressures above 20 mm Hg. Extending the work of Barnard and Kirschner, we have established the existence of two types of slow combustion of ketene corresponding to two temperature ranges. In this first paper, we describe the kinetic and analytical results obtained in the higher temperature range (380–500 °C). The reaction is autocatalytic and shows a low temperature coefficient corresponding to a few kilocalories per mole. The main products are carbon monoxide, formaldehyde, water, and carbon dioxide. No ethylene was detected. We suggest a chain reaction in which formaldehyde is the intermediate responsible for degenerate branching:[Formula: see text]

scholarly journals A First Principle Comparative Study on Chemisorption of H2on C60, C80, and Sc3N@C80in Gas Phase and Chemisorption of H2on Solid Phase C60

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Hongtao Wang ◽  
Lijuan Chen ◽  
Yongkang Lv ◽  
Jianwen Liu ◽  
Gang Feng
Keyword(s):  
High Pressure ◽  
Gas Phase ◽  
Active Sites ◽  
Adsorption Process ◽  
Reaction Path ◽  
Solid Phase ◽  
Dissociative Adsorption ◽  
Chain Reaction ◽  
A Chain ◽  
Initial Adsorption

The chemisorptions of H2on fullerenes C60and C80, endofullerene Sc3C@C80and solid C60were comparatively studied. A chain reaction mechanism for dissociative adsorption of H2on solid C60is proposed under high pressure. The breaking of H–H bond is concerted with the formation of two C–H bonds on two adjacent C60in solid phase. The adsorption process is facilitated by the application of high pressure. The initial H2adsorption on two adjacent C60gives a much lower barrier 1.36 eV in comparison with the barrier of adsorption on a single C60(about 3.0 eV). As the stereo conjugate aromaticity of C60is destructed by the initial adsorption, some active sites are created. Hence the successive adsorption becomes easier with much low barriers (0.6 eV). In addition, further adsorption can create new active sites for the next adsorption. Thus, a chain reaction path is formed with the initial adsorption dominating the whole adsorption process.

scholarly journals RELAP5-3D Code Includes ATHENA Features and Models

2006 ◽  
Author(s):  
Richard A. Riemke ◽  
Cliff B. Davis ◽  
Richard R. Schultz
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Molten Salts ◽  
Working Fluid ◽  
Hydraulic Systems ◽  
Sodium Potassium ◽  
Working Fluids ◽  
Noncondensable Gases ◽  
Magnetohydrodynamic Model

Version 2.3 of the RELAP5-3D computer program includes all features and models previously available only in the ATHENA version of the code. These include the addition of new working fluids (i.e., ammonia, blood, carbon dioxide, glycerol, helium, hydrogen, lead-bismuth, lithium, lithium-lead, nitrogen, potassium, sodium, and sodium-potassium) and a magnetohydrodynamic model that expands the capability of the code to model many more thermal-hydraulic systems. In addition to the new working fluids along with the standard working fluid water, one or more noncondensable gases (e.g., air, argon, carbon dioxide, carbon monoxide, helium, hydrogen, krypton, nitrogen, oxygen, sf6, xenon) can be specified as part of the vapor/gas phase of the working fluid. These noncondensable gases were in previous versions of RELAP5-3D. Recently four molten salts have been added as working fluids to RELAP5-3D Version 2.4, which has had limited release. These molten salts will be in RELAP5-3D Version 2.5, which will have a general release like RELAP5-3D Version 2.3. Applications that use these new features and models are discussed in this paper.

The slow combustion of cyclo propane - II. Analytical results and mechanism

1953 ◽  
Vol 220 (1141) ◽  
pp. 266-277 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Maximum Rate ◽  
Surface Effect ◽  
Reaction Scheme ◽  
Maximum Pressure ◽  
Elementary Reactions ◽  
Analytical Results ◽  
Slow Combustion ◽  
Initial Oxygen

The stable products of the reaction between oxygen and cyclopropane are carbon monoxide and water with small amounts of carbon dioxide, methane and hydrogen. The only organic intermediate formed is formaldehyde, the pressure of which during an experiment rose to a maximum at the time of the maximum rate. This maximum pressure was proportional to the initial cyclopropane pressure and independent of the initial oxygen pressure unless that was very low. Addition of formaldehyde initially reduced the induction period but had little effect on the maximum rate. The initial addition of water slightly catalyzed the reaction, but this was a surface effect. A detailed reaction scheme, which explains the kinetic and analytical results, is proposed, and the various elementary reactions composing it discussed. It is suggested that formaldehyde was formed by means of the production and decomposition of cyclopropylperoxyl (C 3 H 5 O 2 ) radicals and was responsible for the delayed branching (McEwan & Tipper 1953); and that the reaction chains involved OH and HO 2 radicals, termination having occurred by reaction of the latter on the walls.

Gas-Solid Chromatographic Determination of Carbon Monoxide and Carbon Dioxide in Cigarette Smoke

1974 ◽  
Vol 57 (1) ◽  
pp. 1-7
Author(s):  
Arthur D Horton ◽  
Michael R Guerin
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Confidence Intervals ◽  
Cigarette Smoke ◽  
Chromatographic Determination ◽  
Standard Errors ◽  
Sampling Techniques ◽  
Relative Standard

Abstract Gas-solid chromatographic methods are presented for the determination of carbon monoxide, carbon dioxide, or both simultaneously in the gas phase of cigarette smoke. The methods are optimized to allow quantitative determinations on the entire gas phase delivery of the cigarettes rather than single puffs and to allow the use of small numbers of cigarettes. Shortcomings of several sampling techniques are defined, and evidence is presented supporting the utility of Saran bag sampling and containment. Carbon monoxide and carbon dioxide analyses may be performed with relative standard errors of 2—3% and relative confidence intervals (95%) of 6—9% for determinations involving 4—6 cigarettes.

The slow combustion of cyclo pentane - II. Analytical results and mechanism

1958 ◽  
Vol 246 (1244) ◽  
pp. 64-77 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Maximum Rate ◽  
Pressure Change ◽  
Reaction Scheme ◽  
Elementary Reactions ◽  
Slow Combustion ◽  
Initial Oxygen ◽  
Increasing Temperature ◽  
True Measure

The products of the oxidation of cyclo pentane in the gas phase at around 400 °C in an uncoated vessel were water, carbon monoxide and carbon dioxide with smaller amounts of hydrogen, methane, ethylene, propylene, cyclo pentane, formaldehyde, higher aldehydes (mainly acetaldehyde) and acids. It was confirmed that the pressure change was true measure of the extent of reaction. The pressures of higher aldehydes and unsaturates rose to a maximum at about the time of the maximum rate, and the variation of these maximum pressures with initial oxygen and cyclo pentane pressures was investigated. Addition of formaldehyde initially had little effect on the reaction, but addition of higher aldehydes reduced the induction period and increased the maximum rate. The CO/CO 2 ratio increased with increasing temperature and cyclo pentane pressure and was much greater with the boric-acid-coated vessel. Also using this vessel peroxidic material was detected in the products. Higher aldehydes were probably the substances responsible for delayed branching. The various elementary reactions which may have occurred in the system are discussed and a reaction scheme which can explain the products and to some extent the kinetic results is proposed. Cyclo pentylperoxy (C 5 H 9 O 2 ) radicals were probably important both in propagating and terminating the chains.

THE THERMAL CIS–TRANS ISOMERIZATION AND DECOMPOSITION OF METHYL CROTONATE

1963 ◽  
Vol 41 (10) ◽  
pp. 2492-2499 ◽  
Author(s):  
James N. Butler ◽  
Gerald J. Small
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Free Radical ◽  
Gas Phase ◽  
Rate Constant ◽  
Radical Reactions ◽  
Side Reactions ◽  
Free Radical Reactions ◽  
Trans Isomerization

Methyl crotonate undergoes a homogeneous, unimolecular cis–trans isomerization in the gas phase at temperatures from 400 °C to 560 °C. The rate constant for the cis → trans reaction was found to be [Formula: see text]independent of pressure in the range from 0.1 mm to 10 mm. The equilibrium trans/cis ratio is approximately 4.5, independent of temperature, from 200 °C to 500 °C. Simultaneous free-radical reactions also occur, the most important of which are the isomerization to methyl vinylacetate, and the decomposition to give carbon dioxide and the various butene isomers. Side reactions gave carbon monoxide, methane, propylene, numerous other hydrocarbons, and various ethers.

Reaction of Hydrogen Atoms with Carbon Suboxide

1971 ◽  
Vol 49 (5) ◽  
pp. 803-806 ◽  
Author(s):  
Nick Demchuk ◽  
H. D. Gesser
Keyword(s):  
Gas Phase ◽  
Intermediate Formation ◽  
Phase Reaction ◽  
Hydrogen Atoms ◽  
Chain Reaction ◽  
Carbon Suboxide ◽  
Formyl Radical ◽  
Gas Phase Reaction ◽  
Temperature Range ◽  
A Chain

The gas phase reaction of hydrogen atoms with carbon suboxide was studied over the temperature range of−96 to 235 °C and was found to proceed via a chain reaction. The products found were CH4, CO, CH2CO, C2H6, (CHO)2, and polymer. A mechanism is proposed and the chain reaction is explained by the intermediate formation of ketene and the formyl radical.

Gas Phase Electrolysis of Carbon Dioxide to Carbon Monoxide Using Nickel Nitride as the Carbon Enrichment Catalyst

2018 ◽  
Vol 10 (44) ◽  
pp. 38024-38031 ◽  
Author(s):  
Pengfei Hou ◽  
Xiuping Wang ◽  
Zhuo Wang ◽  
Peng Kang
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Nickel Nitride

Gas-Phase Photocatalytic Oxidation of Styrene in a Simple Tubular TiO2 Reactor

2003 ◽  
Vol 6 (2) ◽  
Author(s):  
Marina Krichevskaya ◽  
Sergei Preis
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Uv Irradiation ◽  
Photocatalytic Oxidation ◽  
Humid Air ◽  
Oxygenated Hydrocarbons ◽  
Initial Stage ◽  
By Products

AbstractGas-phase photocatalytic oxidation (PCO) of styrene was studied. Styrene appeared to poison the photocatalyst easily degrading its PCO efficiency at concentrations above certain level. Below this level no poisoning of the photocatalyst was observed. The presence of humidity extended the photocatalyst’s lifetime. The yield of carbon dioxide also increased in humid air, although lower conversion degrees of styrene were observed. Carbon dioxide was the main gaseous PCO product; carbon monoxide was formed in trace amounts. The apparent styrene PCO rate was independent of temperature at the initial stage of oxidation. However, the PCO rate noticeably increased with temperature at stages close to complete photocatalyst poisoning. The photocatalyst’s activity was entirely restored by UV -irradiation in humid airflow: adsorbed by-products were successfully oxidised. The simultaneous PCO of styrene with oxygenated hydrocarbons-alcohols and ethers-resulted in the photocatalyst poisoning along the same pattern as for styrene alone.

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