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.

scholarly journals Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

2007 ◽  
Vol 2007 ◽  
pp. 1-4
Author(s):  
Anna Kachina ◽  
Sergei Preis ◽  
Juha Kallas
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Continuous Flow ◽  
Kinetic Data ◽  
Photocatalytic Oxidation ◽  
Reaction Pathway ◽  
Tubular Reactor ◽  
Order Process ◽  
First Order ◽  
Long Run

Gas-phase photocatalytic oxidation (PCO) and thermal catalytic oxidation (TCO) of dimethylamine (DMA) on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

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.

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]

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.

scholarly journals Gas-Phase and Aqueous Photocatalytic Oxidation of Methylamine: The Reaction Pathways

2007 ◽  
Vol 2007 ◽  
pp. 1-6 ◽  
Author(s):  
Anna Kachina ◽  
Sergei Preis ◽  
German Charles Lluellas ◽  
Juha Kallas
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Continuous Flow ◽  
Photocatalytic Oxidation ◽  
Organic Nitrogen ◽  
Flow Reactor ◽  
Ammonia Nitrogen ◽  
Alkaline Media ◽  
Reaction Pathways ◽  
Continuous Flow Reactor

Photocatalytic oxidation (PCO) of methylamine (MA) on titanium dioxide in aqueous and gaseous phases was studied. A simple batch glass reactor for aqueous PCO and an annular continuous flow reactor for the gas-phase PCO were used. Maximum aqueous PCO efficiency was achieved in alkaline media. Two mechanisms of aqueous PCO—decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite—lead ultimately toCO2, water, ammonia, and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. Volatile PCO products of MA included ammonia, nitrogen dioxide(NO2), nitrous oxide(N2O), carbon dioxide, and water. Thermal catalytic oxidation (TCO) resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The gas-phase PCO kinetics is described by the monomolecular Langmuir-Hinshelwood model. No deactivation ofTiO2catalyst was observed.

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.

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

scholarly journals Photocatalytic oxidation of TCE and MTBE in the Gas phase

2013 ◽  
Vol 10 (2) ◽  
pp. 237-240
Keyword(s):  
Gas Phase ◽  
Photocatalytic Oxidation ◽  
Methyl Tert Butyl Ether ◽  
Inlet Concentration ◽  
Ambient Conditions ◽  
Butyl Ether ◽  
Tert Butyl ◽  
The Impact ◽  
By Products ◽  
Mtbe Decomposition

Photocatalysis is a promising method for eliminating the volatile organic compounds emitted from various industrial processes because mild or ambient conditions are used. Titanium dioxide is commonly used as photocatalyst and ultraviolet light is utilized for decomposing gas phase pollutants. In the present work, the photocatalytic oxidation of methyl tert butyl ether (MTBE) and trichloroethylene (TCE) in the gas phase was studied. The impact of residence time, TCE/MTBE concentration and oxygen concentration on TCE/MTBE conversion and byproduct formation was examined. Acetone and tert-butyl formate were detected at the reactor outlet from MTBE decomposition, whereas dichloroacetyl chloride (DCAC) and phosgene were found as by-products of TCE oxidation. The residence time affected dramatically both TCE and MTBE photo-oxidation as well as by-products existence and configuration. In contrast, the variation of oxygen inlet concentration affected significantly only MTBE conversion. Finally, the increase in MTBE and TCE inlet concentration had as a result decreased conversions observed.

Mathematical Modeling of Heat and Mass Transfer Processes During Pyrolysis and Combustion of a Single Biomass Particle

2012 ◽  
Author(s):  
Y. Haseli ◽  
J. A. van Oijen ◽  
L. P. H. de Goey
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Gas Phase ◽  
Combustion Process ◽  
Combustion Model ◽  
Gas Phase Reactions ◽  
Transfer Processes ◽  
Mass Transfer Processes

A detailed mathematical model is developed for simulation of heat and mass transfer processes during the pyrolysis and combustion of a single biomass particle. The kinetic scheme of Shafizadeh and Chin is employed to describe the pyrolysis process. The light gases formed during the biomass pyrolysis is assumed to consist of methane, carbon dioxide, carbon monoxide, hydrogen and water vapor with given mass fractions relevant to those found in the experiments of high heating conditions. The combustion model takes into account the reactions of oxygen with methane, hydrogen, carbon monoxide, tar and char as well as gasification of char with water vapor and carbon dioxide. Appropriate correlations taken from past studies are used for computation of the rate of these reactions. The model allows calculation of time and space evolution of various parameters including biomass and char densities, gaseous species and temperature. Different experimental data reported in the literature are employed to validate the pyrolysis and combustion models. The reasonable agreement obtained between the predictions and measured data reveals that the presented model is capable of successfully capturing various experiments of wood particle undergoing a pyrolysis or combustion process. In particular, the role of gas phase reactions within and adjacent to particle on the combustion process is examined. The results indicate that for the case of small particles in the order of millimeter size and less, one may neglect any effects of gas phase reactions. However, for larger particles, a combustion model may need to include hydrogen oxidation and even carbon monoxide combustion reactions.

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