Natural Gas to Fuels and Chemicals: Improved Methane Aromatization in an Oxygen‐Permeable Membrane Reactor

Cao, Zhilong; Jiang, Heqing; Luo, Huixia; Baumann, Stefan; Meulenberg, Wilhelm Albert; Aßmann, J.; Mleczko, Lesław; Liu, Yi; Caro, Juergen

doi:10.1002/anie.201307935

Cited by 117 publications

(66 citation statements)

References 48 publications

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“…[5][6][7] Nevertheless, the use of H 2 -permselective membranes for MDA is limited. To date, some of the membrane materials that have been examined include Pd 8 , Pd-Ag [9][10][11][12] , and dense oxides 13,14 . Information regarding the influence of reaction parameters (i.e.…”

Section: Introductionmentioning

confidence: 99%

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

Natesakhawat

Means

Howard

et al. 2015

Catal. Sci. Technol.

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The effectiveness of hydrogen-permselective palladium membrane reactors for non-oxidative methane dehydroaromatization (MDA) over 4 wt% Mo/HZSM-5 catalysts was investigated as a function of weight hourly space velocity (WHSV) at 700 °C and atmospheric pressure. CH4 conversion and aromatic product yield decrease with increasing WHSV from 750 to 9000 cm 3 gcat -1 h -1 . C6H6 is the main C-containing product at and below 3000 cm 3 gcat -1 h -1 whereas C2H4 dominates the C-product distribution at higher WHSVs. Due to selective removal of H2 from the reaction products in catalytic membrane reactors, C6H6 yield is significantly improved over the whole WHSV range compared to those obtained in fixed-bed reactors. H2 recovery is strongly influenced by WHSV as it decreases from 48.3% at 750 cm 3 gcat -1 h -1 to 6.8% at 9000 cm 3 gcat -1 h -1 . There exists a trade-off between catalytic activity and H2 recovery, which results in the maximum enhancement (~360%) in C6H6 yield at 3000 cm 3 gcat -1 h -1 . At this intermediate space velocity, the largest concentration of H2 is found in the retentate stream and helps alleviate coke accumulation particularly on HZSM-5. Carbon is deposited on the inner surface of the membrane reactor portion in contact with the catalyst bed and transports to the outer surface, thus causing H2 permeability to decrease over the 15-h reaction period.Palladium membrane reactors significantly improve C 6 H 6 yield from CH 4 dehydroaromatization on Mo/HZSM-5 catalysts over a wide range of space velocity.

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Section: Introductionmentioning

confidence: 99%

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

Natesakhawat

Means

Howard

et al. 2015

Catal. Sci. Technol.

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“…[3][4][5][6] A challenging application of OTMs would be the oxyfuel process with integrated CO 2 capture. 7,8 However, to survive under real process conditions in the presence of harsh gases (such as CO 2 , H 2 , CH 4 , etc.)…”

Section: Introductionmentioning

confidence: 99%

A CO₂-stable reduction-tolerant Nd-containing dual phase membrane for oxyfuel CO₂capture

et al. 2014

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We report a novel CO 2 -stable reduction-tolerant dual-phase oxygen transport membrane 40 wt% Nd 0.6 Sr 0.4 FeO 3Àd -60 wt% Ce 0.9 Nd 0.1 O 2Àd (40NSFO-60CNO), which was successfully developed by a facile one-pot EDTA-citric sol-gel method. The microstructure of the crystalline 40NSFO-60CNO phase was investigated by combined in situ X-ray diffraction (XRD), scanning electron microscopy (SEM), back scattered SEM (BSEM), and energy dispersive X-ray spectroscopy (EDXS) analyses. Oxygen permeation and long-time stability under CO 2 and CH 4 atmospheres were investigated. A stable oxygen flux of 0.21 cm 3 min À1 cm À2 at 950 C with undiluted CO 2 as sweep gas is found which is increased to 0.48 cm 3 min À1 cm À2 if the air side is coated with a porous La 0.6 Sr 0.4 CoO 3Àd (LSC) layer. All the experimental results demonstrate that the 40NSFO-60CNO not only shows good reversibility of the oxygen permeation fluxes upon temperature cycling, but also good phase stability in a CO 2 atmosphere and under the harsh conditions of partial oxidation of methane to synthesis gas up to 950 C.

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“…[5] Although there have been remarkable achievements in regeneration procedures, [6] developing astable MDAcatalyst is still required to arrive at acommercial process.Aprogress in this direction is seriously hampered by limited understanding of the active sites in the benchmark Mo/ZSM-5 catalyst and the mechanism of methane conversion to benzene and hydrogen. Despite considerable debate on the nature of the active phase,t here is ag rowing consensus that the active sites are confined as highly dispersed Mo species by the zeolite pores in working Mo/ZSM-5 catalysts and that Mo 2 Cn anoparticles on the external surface are inactive.…”

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confidence: 99%

Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM‐5

et al. 2017

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Non-oxidative dehydroaromatization of methane (MDA) is apromising catalytic process for direct valorization of natural gas to liquid hydrocarbons.T he application of this reaction in practical technology is hindered by al acko f understanding about the mechanism and nature of the active sites in benchmark zeolite-based Mo/ZSM-5 catalysts,w hich precludes the solution of problems such as rapid catalyst deactivation. By applying spectroscopya nd microscopy, it is shown that the active centers in Mo/ZSM-5 are partially reduced single-atom Mo sites stabilized by the zeolite framework. By combining ap ulse reaction techniquew ith isotope labeling of methane,M DA is shown to be governed by ah ydrocarbon pool mechanism in whichb enzenei sd erived from secondary reactions of confined polyaromatic carbon species with the initial products of methane activation.The abundance of natural gas reserves calls for the development of an efficient conversion technology to upgrade its principal component, methane,i nto easily transportable chemicals.[1] Several catalytic technologies,w hich could replace the current indirect route involving an expensive synthesis gas generation step,a re being considered. Broadly, we can distinguish between oxidative and non-oxidative direct routes.[2] Among the non-oxidative approaches,c atalytic methane dehydroaromatization (MDA) is one of the most promising methods.A fter the initial reports on MDA almost three decades ago, [3] as ubstantial body of literature has appeared.[4] Thei ndustrial implementation of the MDA process is mainly hindered by rapid catalyst deactivation caused by the deposition of ac arbonaceous material that blocks the catalytically active sites. [5] Although there have been remarkable achievements in regeneration procedures, [6] developing astable MDAcatalyst is still required to arrive at acommercial process.Aprogress in this direction is seriously hampered by limited understanding of the active sites in the benchmark Mo/ZSM-5 catalyst and the mechanism of methane conversion to benzene and hydrogen. Despite considerable debate on the nature of the active phase,t here is ag rowing consensus that the active sites are confined as highly dispersed Mo species by the zeolite pores in working Mo/ZSM-5 catalysts and that Mo 2 Cn anoparticles on the external surface are inactive. [7] Concerning the reaction mechanism, most reports support ab ifunctional pathway in which methane is activated and coupled to ethylene over Mocarbide species,followed by ethylene aromatization over the zeolite Brønsted acid sites. [8] Important challenges in gaining insight into these aspects are the high reaction temperature at which the MDAreaction takes place and its transient nature,w hich involves rapid activation and deactivation stages when the fresh Mo/ZSM-5 catalyst is exposed to am ethane feed. These factors complicate operando spectroscopy and kinetic investigations.A valuable approach in this regard is to increase the temporal resolution by pulsing the reactant over the catalyst an...

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Natural Gas to Fuels and Chemicals: Improved Methane Aromatization in an Oxygen‐Permeable Membrane Reactor

Cited by 117 publications

References 48 publications

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

A CO₂-stable reduction-tolerant Nd-containing dual phase membrane for oxyfuel CO₂capture

Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM‐5

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Natural Gas to Fuels and Chemicals: Improved Methane Aromatization in an Oxygen‐Permeable Membrane Reactor

Cited by 117 publications

References 48 publications

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors

A CO2-stable reduction-tolerant Nd-containing dual phase membrane for oxyfuel CO2capture

Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM‐5

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A CO₂-stable reduction-tolerant Nd-containing dual phase membrane for oxyfuel CO₂capture