Catalytic Oxidation of Methane at Low Space Velocities PDF Download
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Author: Derry W. Marshall
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
The feasibility of removing methane from an airstream by catalytic oxidation at low flows was investigated by passing a one percent, by volume, methane in airstream through an inhouse designed and fabricated stainless steel reactor. The reactor contained either Hopcalite, 5% V2O5 - 5% MoO3 on alumina, or one of the following materials supported on alumina: 0/5% palladium, 0.5% platinum, 0.5% rhodium, and 0.5% ruthenium. Some discontinuity in the data reported in the literature on methane oxidation at or around the transition flow region prompted a closer investigation in this area. In addition, space velocities around 500 fills per hour were used to insure chemical equilibrium and for comparison with the more common value of approximately 15,000 fills per hour used in most industrial applications. Experiments performed using the above catalyst revealed no deleterious effects associated with operating in the transition flow region, but did point out the advantage of using high space velocities for maximum catalyst utilization. The palladium catalyst proved superior to all others tested and catalyzed the reaction to completion at 560 F. Conversion versus temperature curves are plotted for each catalyst flow rate combination and the effect of space velocity on conversion at constant temperature is shown for the Hopcalite and palladium catalysts. Variables which affected the accuracy of experimentation most are discussed and possible improvements suggested. (Author).
Author: Derry W. Marshall
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
The feasibility of removing methane from an airstream by catalytic oxidation at low flows was investigated by passing a one percent, by volume, methane in airstream through an inhouse designed and fabricated stainless steel reactor. The reactor contained either Hopcalite, 5% V2O5 - 5% MoO3 on alumina, or one of the following materials supported on alumina: 0/5% palladium, 0.5% platinum, 0.5% rhodium, and 0.5% ruthenium. Some discontinuity in the data reported in the literature on methane oxidation at or around the transition flow region prompted a closer investigation in this area. In addition, space velocities around 500 fills per hour were used to insure chemical equilibrium and for comparison with the more common value of approximately 15,000 fills per hour used in most industrial applications. Experiments performed using the above catalyst revealed no deleterious effects associated with operating in the transition flow region, but did point out the advantage of using high space velocities for maximum catalyst utilization. The palladium catalyst proved superior to all others tested and catalyzed the reaction to completion at 560 F. Conversion versus temperature curves are plotted for each catalyst flow rate combination and the effect of space velocity on conversion at constant temperature is shown for the Hopcalite and palladium catalysts. Variables which affected the accuracy of experimentation most are discussed and possible improvements suggested. (Author).
Author: Marvin Warshay
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 24
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Author:
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Category :
Languages : en
Pages : 17
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Support effects on catalytic reactions, especially of highly exothermic oxidation reactions, can be very significant. Since we had shown that a MoO3/SiO2 catalyst, especially when used in a double bed configuration with a Sr/La2O3 catalyst, can selectively oxidize methane to formaldehyde, the role of the SiO2 support was investigated. Therefore, partial oxidation of methane by oxygen to form formaldehyde, carbon oxides, and C2 products (ethane and ethene) has been studied over silica catalyst supports (fumed Cabosil and Grace 636 silica gel) in the 630-780°C temperature range under ambient pressure. When relatively high gas hourly space velocities (GHSV) were utilized, the silica catalysts exhibit high space time yields (at low conversions) for methane partial oxidation to formaldehyde, and the C2 hydrocarbons were found to be parallel products with formaldehyde. In general, the selectivities toward CO were high while those toward CO2 were low. Based on the present results obtained by a double catalyst bed experiment, the observations of product composition dependence on the variation of GHSV (i.e. gas residence time), and differences in apparent activation energies of formation of C2H6, and CH2O, a reaction mechanism is proposed for the activation of methane over the silica surface. This mechanism can explain the observed product distribution patterns (specifically the parallel formation of formaldehyde and C2 hydrocarbons).
Author:
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ISBN:
Category :
Languages : en
Pages : 280
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Author: Keith Lawrence Hohn
Publisher:
ISBN:
Category :
Languages : en
Pages : 318
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Author: D.M. Bibby
Publisher: Elsevier
ISBN: 0080960707
Category : Technology & Engineering
Languages : en
Pages : 759
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Book Description
This proceedings volume comprises the invited plenary lectures, contributed and poster papers presented at a symposium organised to mark the successful inauguration of the world's first commercial plant for production of gasoline from natural gas, based on the Mobil methanol-to-gasoline process. The objectives of the Symposium were to present both fundamental research and engineering aspects of the development and commercialization of gas-to-gasoline processes. These include steam reforming, methanol synthesis and methanol-to-gasoline. Possible alternative processes e.g. MOGD, Fischer-Tropsch synthesis of hydrocarbons, and the direct conversion of methane to higher hydrocarbons were also considered.The papers in this volume provide a valuable and extremely wide-ranging overview of current research into the various options for natural gas conversion, giving a detailed description of the gas-to-gasoline process and plant. Together, they represent a unique combination of fundamental surface chemistry catalyst characterization, reaction chemistry and engineering scale-up and commercialization.
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Category :
Languages : en
Pages : 17
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The objectives of this research were to achieve and understand the partial oxidation of methane to oxygenates and C2 hydrocarbons over dual redox catalysts. The catalysts were based on oxidic materials that will exhibit structural and thermal stability for long reactor lifetimes. A continuous flow reactor system with oxygen or air as the oxidizing gas, rather than nitrous oxide, was utilized over a wide range of temperatures ((less-than or equal to)1000°C), with variable gas hourly space velocity, in order to maximize the space time yields of the desired products. All of the investigated processes are catalytic and are aimed at minimizing gas phase reactions.
Author:
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ISBN:
Category :
Languages : en
Pages : 128
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A theoretical model and a computer simulation on methane (CH4) reduction in a simulated natural gas exhaust mixture are performed for a Reverse-Flow Oxidation Catalyst. This theoretical model is to predict the conversion of methane flowing through an oxidation catalyst with periodic reversal of flow direction. The model developed for this purpose is a transient, 1-Dimensional plug flow model with gas phase reactions and surface reactions. The derivation of the model resulted in the mole balance equation and the energy balance equation for the gas phase and the solid phase. The momentum equation for this model is neglected as it is assumed that there is no pressure drop across the catalyst. A FORTRAN code was developed to simulate the forward flow and the reverse flow of the gas species through the catalyst. This code can have a symmetrical or an asymmetrical switching according to the user. It also gives an option of running the code either in the forward direction or with periodic switching to analyze the effect of switching. With this code, the optimum switching time for the maximum conversion of methane was found. The effect of various parameters such as the length of the catalyst, the concentration of the gas species, pre-exponential term and the activation energy was also analyzed. The results show that the optimum switching frequency is 25 seconds for all space velocities for a 10 cm long catalyst with 2000 ppm of inlet methane. The increase in the v conversion of methane when compared to the unidirectional flow was found to be 47% at 450°C for a gas hourly space velocity of 50,000 hr−1. It was also found that, at 450°C for a gas hourly space velocity of 50,000 hr−1, the pre-exponential factor and the length of the catalyst had negligible effect on the conversion of methane. The activation energy and the inlet concentration had a significant effect on the methane conversion which is discussed in further chapters. It was also found that symmetric switching had increased solid temperature profile and methane conversion efficiency when compared to the asymmetric switching frequency.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 912
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Author: Paul Matthew Witt
Publisher:
ISBN:
Category :
Languages : en
Pages : 234
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