Investigation of the stability of Zn-based HZSM-5 catalysts for methane dehydroaromatization

Abdelsayed, Victor; Smith, Mark W.; Shekhawat, Dushyant

doi:10.1016/j.apcata.2015.08.017

Cited by 62 publications

(45 citation statements)

References 70 publications

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“…Furthermore, Table 2 reports the acidic properties for different zinc-containing samples. As expected from previous investigations, [3,7,15] we notice an increase in density of weak acid sites and decrease in strong acid sites, probably caused by coordinative unsaturated Zn 2 + species as the zinc loading increases.…”

Section: Resultssupporting

confidence: 90%

“…Generally, dehydroaromatization provides strongly reducing environment. Consequently, unreactive ZnO may be reduced to metallic zinc and leave the catalyst or some of reactive zinc species could anchor to the acid sites . Therefore, it is believed that the observed catalytic performance for all of the catalysts is the result of zinc, retained on active sites, strongly bound to the zeolite.…”

Section: Resultsmentioning

confidence: 99%

“…Based on literature, [6,7,15,26] two types of zinc species are formed in a zinc-loaded ZSM-5. The spectator zinc, which is ZnO that can be easily reduced to metallic zinc with hydrogen, and the incorporated zinc that is hardly reduced.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, unreactive ZnO may be reduced to metallic zinc and leave the catalyst or some of reactive zinc species could anchor to the acid sites. [7,15,26] Therefore, it is believed that the observed catalytic performance for all of the catalysts is the result of zinc, retained on active sites, strongly bound to the zeolite. Moreover, ICP-OES results of the spent catalysts (Table 2) are in good agreement with this assumption because in the catalysts with 5 wt % zinc loading, merely about one third of the zinc remains in the catalyst after 30 h TOS.…”

Section: Resultsmentioning

confidence: 99%

“…[13,14] In order to directly convert alkanes to aromatics, a bifunctional catalyst is required, which in addition to the acid function comprises the dehydrogenation functionality of metal such as Ga, Zn, Mo, Re or Pt. [15][16][17][18][19][20][21][22][23] Numerous studies demonstrated that incorporation of Lewis acid metals such as Zn into zeolites modifies the surface acidity and enhances selectivity to BTX in light alkane dehydroaromatization. [7,15,18,[24][25][26][27] However, only a few studies have been dedicated to the performance and catalytic life-time enhancement of Zn-containing zeolite catalyst for ethane direct conversion to aromatics.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Catalytic Performance of Zn‐containing HZSM‐5 upon Selective Desilication in Ethane Dehydroaromatization Process

et al. 2020

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The effect of introducing mesoporosity on the catalytic stability and selectivity of Zn‐containing ZSM‐5 catalysts was investigated for direct conversion of ethane to high‐value aromatics. Voids and mesopores were created in the zeolite (Si/Al=40) by selective desilication (recrystallization) using ammonium hydroxide and cetyltrimethylammonium bromide. Zinc was incorporated in the samples by incipient wetness impregnation to achieve different concentrations of 0.5, 1 and 5 wt %. The samples were characterized by XRD, N2 physisorption, TGA, NH3‐TPD, ICP‐OES, FTIR, 1H, 27Al and 29Si solid‐state MAS NMR. The desilicated samples were compared to their parent analogues for ethane conversion to aromatics such as benzene, toluene and xylenes (BTX). All of the desilicated samples showed an improvement in BTX yield and catalytic stability. Thus, the presence of mesoporosity increases the accessibility to the active sites and facilitates the mass transfer of aromatic compounds, which result in higher performance and catalytic stability of the desilicated ZSM‐5 samples containing zinc.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced Catalytic Performance of Zn‐containing HZSM‐5 upon Selective Desilication in Ethane Dehydroaromatization Process

et al. 2020

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Methane Activation Over Zeolites

Shah¹,

Taylor²

2022

Heterogeneous Catalysis for Sustainable Energy

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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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Investigation of the stability of Zn-based HZSM-5 catalysts for methane dehydroaromatization

Cited by 62 publications

References 70 publications

Enhanced Catalytic Performance of Zn‐containing HZSM‐5 upon Selective Desilication in Ethane Dehydroaromatization Process

Enhanced Catalytic Performance of Zn‐containing HZSM‐5 upon Selective Desilication in Ethane Dehydroaromatization Process

Methane Activation Over Zeolites

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

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