A detailed reaction mechanism for oxidative coupling of methane over Mn/Na2WO4/SiO2 catalyst for non-isothermal conditions

Karakaya, Canan; Zhu, Huayang; Loebick, Codruta Zoican; Weissman, Jeffrey G.; Kee, Robert J.

doi:10.1016/j.cattod.2018.02.023

Cited by 71 publications

(66 citation statements)

References 80 publications

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“…The preferred formation of CO at a shorter residence time can be attributed to the gas-phase formation of CO from methyl radicals. 5,49 CO can be preferentially produced when a methyl radical reacts with O 2 instead of another methyl radical, increasing the CO/CO 2 ratio.…”

Section: Effects Of Catalyst Bed Thickness and Feed Ow Rate On Catalmentioning

confidence: 99%

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

et al. 2020

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Section: Effects Of Catalyst Bed Thickness and Feed Ow Rate On Catalmentioning

confidence: 99%

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

et al. 2020

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“…However, OCM is characterized by a trade-off between achieving high (low) C2 selectivity at conditions where CH4 conversion is low (high), resulting in non-economical C2 yields [2]. Since the pioneering work of Keller and Bhasin [3] and despite extensive research in OCM catalysis, only the recently developed nanowire catalysts by Siluria Technologies have managed to bring closer the commercial realization of OCM [4,5]. A need for novel reactor design that minimizes the inherent C2 yield limitations of OCM is, hence, imperative, and highly economically and environmentally relevant [6].…”

Section: Accepted M M a N U mentioning

confidence: 99%

Influencing selectivity in the oxidative coupling of methane by modulating oxygen permeation in a variable thickness membrane reactor

Onoja

Wang

Kechagiopoulos

2019

Chemical Engineering and Processing - Process Intensification

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The Oxidative Coupling of Methane (OCM) has been considered for years as a promising alternative for the production of higher hydrocarbons, namely ethane and ethylene. Nonetheless, OCM's inherent conversion-versus-selectivity limitations have not allowed till now for economical C2 yields to be achieved. Reactor engineering studies guided by a detailed mechanistic description of the reaction can directly contribute to obtaining an understanding of these limitations. In this work, a Variable Thickness Membrane Reactor (VTMR) is proposed, wherein O2 permeation along the reactor is modulated, aiming at maximizing C2 selectivity. 1D and 2D reactor simulations are carried out to compare the performance of this reactor to conventional co-feed Packed Bed Reactors (PBR) and Membrane Reactors without variable thickness (MR). Particular attention is given on the impact of gas phase reactions on C2 selectivity, while the effect of surface exchange kinetics on both sides of the membrane and bulk diffusion of O2 across the membrane is discriminated. When identical operating conditions (T = 1073 K, P = 1 atm, Space time = 7.85 s) and reactor geometry (Length = 0.1 m, Diameter = 0.01 m) were evaluated, the optimization performed of the VTMR configuration achieved a C2 selectivity of 67.26 %, in comparison to 47.86 % and 29.87 % for the MR and PBR, respectively, highlighting the potential of the concept.

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“…demonstrated the simulation of the combined homogeneous-heterogeneous reaction network to reproduce experimental results obtained by Mn/Na2WO4/SiO2 catalysts [30] and La2O3/CeO2 catalysts [31] under non-isothermal conditions. Although the above-mentioned reaction simulations have had some success to describe to some degree, there still remains some ambiguity to account for the measured yield and selectivity.…”

Section: Introductionmentioning

confidence: 97%

“…[24,25] There are some reports that combine the radical chemistry with elementary surface reaction to estimate achievable C2 product yields. [23,[26][27][28][29][30][31] Early work by Labinger and Ott demonstrated the importance of including C3 product reaction to reasonably describe the loss of product yield at high conversions. [26] Mims et al established the methodology of combining a reaction network of 447 elementary gas-phase reactions together with some representative heterogeneous reactions to explain the measured distribution of the products.…”

Section: Introductionmentioning

confidence: 99%

Impact of OH Radical Generator Involvement in the Gas‐Phase Radical Reaction Network on the Oxidative Coupling of Methane—A Simulation Study

Baslyman

Sarathy

et al. 2019

Energy Tech

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The impact of OH• generation during the oxidative coupling of methane (OCM) was simulated using state-of-the-art gas-phase chemistry and a comprehensive chemical kinetic model. The inclusion of the quasi-equilibrated formation of OH• from a H2O-O2 mixture into the combustion chemistry network enhanced the CH4 conversion rate and C2 selectivity, consistent with the previously proposed mechanism involving catalytically generated OH•. The OH-pathway increased the CH3• concentration resulting in an enhanced transformation rate from CH3• to C2H6 (second-order in CH3•) more than to CO (first-order in CH3•). Relative to other H-abstracting radical species, the OH• weakened the sensitivity of the H abstraction rate constant to C-H bond energy, or lower 2 6 4 C H CH / kk , which comparatively slows the C2H6 conversion rate relative to CH4, thus enhancing C2 selectivity. Concurrent dehydrogenation of C2H6 to C2H4 may maximize the C2H4 selectivity even after O2 depletion. With the involvement of the OH•-mediated pathway, this study addresses the effects of Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))

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A detailed reaction mechanism for oxidative coupling of methane over Mn/Na2WO4/SiO2 catalyst for non-isothermal conditions

Cited by 71 publications

References 80 publications

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

Influencing selectivity in the oxidative coupling of methane by modulating oxygen permeation in a variable thickness membrane reactor

Impact of OH Radical Generator Involvement in the Gas‐Phase Radical Reaction Network on the Oxidative Coupling of Methane—A Simulation Study

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A detailed reaction mechanism for oxidative coupling of methane over Mn/Na2WO4/SiO2 catalyst for non-isothermal conditions

Cited by 71 publications

References 80 publications

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O2, surface lattice oxygen, and CO2 on the C2+ selectivity

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O2, surface lattice oxygen, and CO2 on the C2+ selectivity

Influencing selectivity in the oxidative coupling of methane by modulating oxygen permeation in a variable thickness membrane reactor

Impact of OH Radical Generator Involvement in the Gas‐Phase Radical Reaction Network on the Oxidative Coupling of Methane—A Simulation Study

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Product

Resources

About

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity