Kinetics of oxidative coupling of methane: Bridging the gap between comprehension and description

Sinev, M. Yu.; Fattakhova, Z. T.; Lomonosov, V. I.; Gordienko, Yu. A.

doi:10.1016/s1003-9953(08)60128-0

Cited by 110 publications

(88 citation statements)

References 42 publications

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“…The feed temperature used (furnace temperature) for each CH 4 /O 2 ratio was different because of the different ignition temperatures that were exhibited. As expected, the feed temperature for ignition increased from 600 8C for CH 4 /O 2 = 7 ( Figure 2) to 640 8C for CH 4 /O 2 = 9 ( Figure 3) and to 730 8C for CH 4 /O 2 = 11 ( Figure 4). However, the peak reactor temperatures were relatively close to one another at 810, 790, and 840 8C for CH 4 /O 2 = 7, 9, and 11, respectively.…”

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confidence: 51%

“…Similar uncertainty would be expected to exist between the temperature and concentration profiles as well. In Figures 2, 3, and 4, the spatially resolved temperature and species mole percent profiles are presented for CH 4 /O 2 = 7, 9, and 11, respectively, without the use of a diluent gas. A total of nine species were quantified: CH 4 , O 2 , C 2 H 6 , C 2 H 4 , C 3 H 8 /C 3 H 6 (C 3 ), H 2 , H 2 O, CO, and CO 2 .…”

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confidence: 99%

“…In Figures 2, 3, and 4, the spatially resolved temperature and species mole percent profiles are presented for CH 4 /O 2 = 7, 9, and 11, respectively, without the use of a diluent gas. A total of nine species were quantified: CH 4 , O 2 , C 2 H 6 , C 2 H 4 , C 3 H 8 /C 3 H 6 (C 3 ), H 2 , H 2 O, CO, and CO 2 . With the exception of the concentration of H 2 O, which was calculated from oxygen atom balances, all of the species were quantified directly from GC measurements by using a multipoint GC calibration process performed before the OCM experiments.…”

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confidence: 99%

“…It has been recognized that to make progress in the OCM an improved quantitative understanding of the underlying detailed chemical kinetic mechanisms (DCKMs) of the coupled surface and gas-phase reactions must be developed and validated over the very broad range of conditions encountered in the process. [3][4][5][6] DCKMs comprise a comprehensive description of chemical transformations in terms of irreducible chemical events or elementary reactions for which independent rate coefficient parameters, frequently expressed in the form k = AT n exp(ÀE/RT), are either available from direct measurements or estimated from theoretical considerations. [3,[5][6][7] DCKMs are then combined with models describing the transport phenomena for the realistic simulation of the performance of the OCM reactors.…”

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New Insights into the Oxidative Coupling of Methane from Spatially Resolved Concentration and Temperature Profiles

2013

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Oxidative coupling of methane (OCM) is a high-temperature process involving the transformation of methane into ethane and ethylene, which are valuable intermediates for the chemical processing industry.[1] Despite decades of long research that has resulted in thousands of papers and hundreds of patents, OCM still remains at the research stage. Although many OCM catalysts have been reported, [2] there appears to be an upper limit for the yield of C 2 + products of approximately 25 % per reactor pass, for which the kinetic reasons are largely unknown. It has been recognized that to make progress in the OCM an improved quantitative understanding of the underlying detailed chemical kinetic mechanisms (DCKMs) of the coupled surface and gas-phase reactions must be developed and validated over the very broad range of conditions encountered in the process. [3][4][5][6] DCKMs comprise a comprehensive description of chemical transformations in terms of irreducible chemical events or elementary reactions for which independent rate coefficient parameters, frequently expressed in the form k = AT n exp(ÀE/RT), are either available from direct measurements or estimated from theoretical considerations. [3,[5][6][7] DCKMs are then combined with models describing the transport phenomena for the realistic simulation of the performance of the OCM reactors. [3,5,7] With the availability of DCKMs, we will then be in a better position to identify improved OCM conditions, superior reactor configurations, and new leads for catalytic materials that are needed to exceed the 25 % limit for C 2 + product yields.[3]Validation of DCKMs requires experimental data of high information content because of the presence of a large number of species participating in an even larger number of elementary reactions. Although DCKMs for OCM have been reported in the past, [3,6] they were all validated by using integral reactor data, that is, reactor exit conditions. However, this is not a particularly demanding test for mechanism validation. In fact, different DCKMs can readily predict similar OCM reactor exit concentrations, as estimated kinetic parameters are used for many of the elementary reactions. Therefore, the performance of more comprehensive validation tests such as the prediction of the absolute concentration profiles of all the major and minor species within the catalytic packed-bed reactors is necessary for the development of truly predictive DCKMs for the OCM process. However, we are not aware of such information-rich data sets in the open OCM literature.Herein, we report, for the first time, the spatially resolved comprehensive species concentrations and temperature profiles in a fixed-bed OCM reactor by using microprobe sampling. Although microprobe sampling techniques have long been used in high-temperature flame-combustion research to obtain spatial temperature and concentration profiles, [8][9][10] their adaptation to and use in heterogeneous catalysis is relatively recent. One of the earliest applications of microprobe sampling to cataly...

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confidence: 99%

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New Insights into the Oxidative Coupling of Methane from Spatially Resolved Concentration and Temperature Profiles

2013

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“…[28,29] [31] steht derzeit die Natur der aktiven Spezies, bei der es sich nach Lunsford [30b, 32] um ein sauerstoffzentriertes Radikal handelt (Schema 3). Hinsichtlich des geschwindigkeitsbestimmenden Schrittes besteht Konsens, dass es sich hierbei um den homolytischen Bruch der C-H-Bindung von Methan handelt.…”

Section: Dehydrierung Vonunclassified

Chemie mit Methan: Studieren geht über Probieren!

Schwarz

2011

Angewandte Chemie

170

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Konzeptionelle Überlegungen zu und mechanistische Aspekte von vier scheinbar einfachen chemischen Umsetzungen, die in der Chemie von Methan von Bedeutung sind, werden in diesem Aufsatz behandelt: 1) die metallvermittelte Dehydrierung unter Bildung von Metallcarbenkomplexen, 2) die Wasserstoffabstraktion als Schlüsselschritt der oxidativen Dimerisierung von Methan, 3) der Mechanismus der CH4→CH3OH‐Umwandlung, und 4) die Reihenfolge der C‐H‐ und O‐H‐Bindungsaktivierung und die Frage nach dem geschwindigkeitsbestimmenden Schritt in der selektiven Oxidation von Methanol zu Formaldehyd. Moderne Gasphasenexperimente, in Verbindung mit Elektronenstrukturrechnungen, liefern Einblicke in elementare Reaktionsschritte auf molekularer Ebene und enthüllen reaktionsmechanistische Details. Die Ergebnisse dieser Untersuchungen werden, wo dies angebracht erscheint, mit Beobachtungen aus entsprechenden Studien in Lösung oder auf Oberflächen verglichen.

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Oxidative Functionalization of Methane on Heterogeneous Catalysts

Sanchez‐Sanchez

Lercher

2018

Alkane Functionalization

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Kinetics of oxidative coupling of methane: Bridging the gap between comprehension and description

Cited by 110 publications

References 42 publications

New Insights into the Oxidative Coupling of Methane from Spatially Resolved Concentration and Temperature Profiles

New Insights into the Oxidative Coupling of Methane from Spatially Resolved Concentration and Temperature Profiles

Chemie mit Methan: Studieren geht über Probieren!

Oxidative Functionalization of Methane on Heterogeneous Catalysts

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