Progress in Nonoxidative Dehydroaromatization of Methane in the Last 6 Years

Sun, Kewen; Ginosar, Daniel M.; He, Ting; Zhang, Yulong; Fan, Maohong; Chen, Ruiping

doi:10.1021/acs.iecr.7b04707

Cited by 109 publications

(74 citation statements)

References 117 publications

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“…ZSM‐5 belonging to 10MR family seems to be the optimal choice as its confinement allows formation of naphthalene, benzene, toluene and xylenes, while restricting further growth to polycondensed structures. Similarly to ZSM‐5, many other 10MR zeolites exhibit high selectivity to aromatics ,. Kan et al.…”

Section: Topology Brønsted Acidity and The Aromatization Reactionsmentioning

confidence: 99%

Progress in Developing a Structure‐Activity Relationship for the Direct Aromatization of Methane

et al. 2018

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To secure future supply of aromatics, methane is a commercially interesting alternative feedstock. Direct conversion of methane into aromatics combines the challenge of activating one of the strongest C−H bonds in all hydrocarbons with the selective aromatization over zeolites. To address these challenges, smart catalyst and process design are a must. And for that, understanding the most important factors leading to successful methane C−H bond activation and selective aromatization is needed. In this review, we summarize mechanistic insight that has been gained so far not only for this reaction, but also for other similar processes involving aromatization reactions over zeolites. With that, we highlight what can be learnt from similar processes. In addition, we provide an overview of characterization tools and strategies, which are useful to gain structural information about this particular metal‐zeolite system at reaction conditions. Here we also aim to inspire future characterization work, by giving an outlook on characterization strategies that have not yet been applied for the methane dehydroaromatization catalyst, but are promising for this system.

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Section: Topology Brønsted Acidity and The Aromatization Reactionsmentioning

confidence: 99%

Progress in Developing a Structure‐Activity Relationship for the Direct Aromatization of Methane

et al. 2018

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“…Methane dehydroaromatisation (MDA) is a promising route for the valorisation of CH 4 into higher value chemicals as it converts methane directly into aromatics and light hydrocarbons giving H 2 as co‐product. Mo‐containing ZSM‐5 zeolites are among the most studied catalysts for this reaction, with the pore dimensions of the MFI structure being key to provide shape selectivity to benzene (up to 80 %) …”

Section: Introductionmentioning

confidence: 99%

“…Mo-containing ZSM-5 zeolites are among the most studied catalysts for this reaction, with the pore dimensions of the MFI structure being key to provide shape selectivity to benzene (up to 80 %). [1][2][3][4][5][6] It has been traditionally accepted that MDA over Mo/ zeolites occurs via a bifunctional mechanism involving two different active sites. [2,3,[7][8][9][10] According to this mechanism, molybdenum species constitute the sites responsible for methane activation, forming H 2 as well as C 2 H x and C 3 H x intermediates, which subsequently transform into aromatic products over the zeolite Brønsted acid sites (BAS) associated to framework Al 3 + .…”

Section: Introductionmentioning

confidence: 99%

Implications of the Molybdenum Coordination Environment in MFI Zeolites on Methane Dehydroaromatisation Performance

et al. 2019

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The structure and activity of Mo/Silicalite‐1 (MFI, Si/Al=∞) were compared to Mo/H‐ZSM‐5 (MFI, Si/Al=15), a widely studied catalyst for methane dehydroaromatisation (MDA). The anchoring mode of Mo was evaluated by in situ X‐ray absorption spectroscopy (XAS) and density functional theory (DFT). The results showed that in Mo/Silicalite‐1, calcination leads to dispersion of MoO3 precursor into tetrahedral Mo‐oxo species in close proximity to the microporous framework. A weaker interaction of the Mo‐oxo species with the Silicalite‐1 was determined by XAS and DFT. While both catalysts are active for MDA, Mo/Silicalite‐1 undergoes rapid deactivation which was attributed to a faster sintering of Mo species leading to the accumulation of carbon deposits on the zeolite outer surface. The results shed light onto the nature of the Mo structure(s) while evidencing the importance of framework Al in stabilising active Mo species under MDA conditions.

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“…This generates another major problem, namely, the coke formation resulting in catalyst deactivation. The problem of coking over zeolite‐supported catalysts, which are the most studied for this reaction, remains unsolved to date …”

Section: Introductionmentioning

confidence: 99%

“…The problem of coking over zeolite-supported catalysts, which are the most studied for this reaction, remains unsolved to date. 3,4 The majority of research on direct nonoxidative catalytic methane conversion deals with methane dehydroaromatization (MDA), and the most extensively studied catalyst for this purpose is Mo/HZSM-5. Typically, 1 to 6 wt% of molybdenum loading is used.…”

Section: Introductionmentioning

confidence: 99%

Nonoxidative methane activation, coupling, and conversion to ethane, ethylene, and hydrogen over Fe/HZSM‐5, Mo/HZSM‐5, and Fe–Mo/HZSM‐5 catalysts in packed bed reactor

et al. 2019

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Summary A high abundance of methane and its relatively low price make it an attractive raw feedstock for the production of ethylene, which is in the consumer demand in recent years. Direct catalytic nonoxidative conversion is interesting, because it could be utilized on natural gas well sites. Monometallic and bimetallic Fe and Mo catalysts were prepared for the purpose of the coupling to ethane and ethene. Three supported materials were synthesized with the following loading of metal: 2.5‐wt% Fe, 5.0‐wt% Fe, and 2.5‐wt% Mo on HZSM‐5. Process' chemical reactions were also catalyzed with a constant 2.5‐wt% Mo/HZSM‐5, which had different amounts of Fe, namely, 0.5, 1.0, and 2.5 wt%. Fourier transform infrared (FTIR), N2 adsorption/desorption, NH3 temperature‐programmed desorption (TPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) were applied for characterization. Coke, accumulated on spent solids, was determined by thermogravimetric analysis (TGA). Activity was evaluated in quartz‐packed bed reactor. All surfaces suffered from deactivation due to carbon formation. The addition of Fe to Mo increased CH4 reacted. The highest selectivity for alkenes was achieved over 1.0‐wt% Fe to 2.5‐wt% Mo/HZSM‐5. At the peak of performance, the C‐based reactivity was 52% for olefins and 2% for alkanes. Stability was accomplished over 2.5‐wt% Fe/HZSM‐5, where the rate of C2 synthesis was comparatively stable for 20 hours of the time on stream. The selective C‐basis yield for C2H4 and C2H6 was 36% and 23%, respectively. The lowest measured quantity of (carbonaceous) by‐products was deposited on 2.5‐wt% Fe/HZSM‐5 after 26 hours. Propylene was detected very limitedly.

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Progress in Nonoxidative Dehydroaromatization of Methane in the Last 6 Years

Cited by 109 publications

References 117 publications

Progress in Developing a Structure‐Activity Relationship for the Direct Aromatization of Methane

Progress in Developing a Structure‐Activity Relationship for the Direct Aromatization of Methane

Implications of the Molybdenum Coordination Environment in MFI Zeolites on Methane Dehydroaromatisation Performance

Nonoxidative methane activation, coupling, and conversion to ethane, ethylene, and hydrogen over Fe/HZSM‐5, Mo/HZSM‐5, and Fe–Mo/HZSM‐5 catalysts in packed bed reactor

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