Spatial distribution and catalytic performance of metal–acid sites in Mo/MFI catalysts with tunable meso-/microporous lamellar zeolite structures

Wu, Yiqing; Emdadi, Laleh; Oh, Su Cheun; Sakbodin, Mann; Liu, Dongxia

doi:10.1016/j.jcat.2014.12.022

Cited by 55 publications

(27 citation statements)

References 59 publications

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“…The mesh prevented the spill of the sample and allowed access to the Si-or Al-precursor vapor in the ALD process. The ALD-Si was carried out by alternative exposure of zeolite sample to tris(dimethylamino)silane (TDMAS, [45,46]. The same setup was used for the following organic base titration and gas-phase catalytic reaction studies.…”

Section: Ald Modification Of Pmww and Pmfi Zeolitesmentioning

confidence: 99%

“…To determine the number of Brønsted acid sites on external surface or in mesopores (N ext, H +), and the fraction of external acid sites (f ext, H+ = N ext, H + / N total, H +) in ALD modified PMFI and PMWWzeolites, methanol reaction to DME in the presence of DTBP organic base was carried out. The rate loss upon DTBP saturation of external acid sites reflects the degree of accessibility of acid sites to bulky DTBP molecules, and hence, the number and fraction of external acid sites can be evaluated[45].…”

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confidence: 99%

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Tuning external surface of unit-cell thick pillared MFI and MWW zeolites by atomic layer deposition and its consequences on acid-catalyzed reactions

Lü

Emdadi

et al. 2016

Journal of Catalysis

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The pillared MWW (PMWW or MCM-36) and pillared MFI (PMFI) zeolites are 2dimensional (2D) catalytically active materials made by pillaring of layered MCM-22(P) and multilamellar MFI precursors, respectively. The single-or near single-unit-cell thick 2D microporous layers in PMWW and PMFI expose comparable number of external surface acid sites (i.e., acid sites enclosed in mesopores between zeolitic layers) to those in micropores, which become important or dominant contributor to the catalytic properties. Although the acidity and catalytic activities of PMWW and PMFI have been studied, modification of their external surfaces and its implications on catalytic reactions are not available. In the present study, we report the tailoring of external surfaces of PMWW and PMFI zeolites by atomic layer deposition (ALD) of silicon (ALD-Si) and aluminum (ALD-Al), respectively. The textural, acidic and catalytic properties of the ALD modified pillared zeolites were investigated using a variety of characterization methods. ALD-Al and ALD-Si modifications kept micropore almost intact, but resulted in significant reduction in mesopore volume and considerable changes in external surface composition and acidity. The catalytic tests showed that intrinsic catalytic behavior of Brønsted acid sites in ALD modified pillared zeolites was similar to their parent counterparts. In diffusion constrained parallel reactions, ALD of Al-or Si-species altered catalyst selectivity. In addition, ALD of Si-species on PMFI zeolite deactivated surface active sites, which resulted in improved catalytic activity in direct methane aromatization reactions under optimal ALD cycles. The study exemplified for the first time that ALD is an effective tool for tuning the surface properties of 2D unit-cell thick zeolites.

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Section: Ald Modification Of Pmww and Pmfi Zeolitesmentioning

confidence: 99%

mentioning

confidence: 99%

Tuning external surface of unit-cell thick pillared MFI and MWW zeolites by atomic layer deposition and its consequences on acid-catalyzed reactions

Lü

Emdadi

et al. 2016

Journal of Catalysis

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“…However, it suffers rapid deactivation due to serious coke formation under practically required severe conditions [5][6][7][8]. Various approaches have attempted to tackle this problem, which include promotion of mass transfer by using zeolites with mesoporous/microporous hierarchical structures [9,10], optimization of the Si/Al ratios of the zeolites [11][12][13], silane modification of the zeolite surfaces [14,15], modification of the active metal composition [16][17][18], and addition of CO 2 , CO, or H 2 into the CH 4 feed [19][20][21][22][23][24]. However, no satisfactory solution has been found as yet.…”

Section: Introductionmentioning

confidence: 99%

The distribution of coke formed over a multilayer Mo/HZSM-5 fixed bed in H2 co-fed methane aromatization at 1073 K: Exploration of the coking pathway

Song

Suzuki

et al. 2015

Journal of Catalysis

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“…Wu et al designed hierarchical micro–mesoporous Mo‐modified lamellar MFI zeolites with remarkable selectivity for methane dehydroaromatization; a 95% selectivity to monocyclic aromatic was observed for 2D Mo/MFI with the optimized ratio of micro‐ and mesopores. However, overcoming the current conversion limitation of the discussed Mo‐supported 2D zeolites (below 5%) remains a challenge.…”

Section: D Zeolitesmentioning

confidence: 99%

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis

et al. 2018

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2D oxide nanomaterials constitute a broad range of materials, with a wide array of current and potential applications, particularly in the fields of energy storage and catalysis for sustainable energy production. Despite the many similarities in structure, composition, and synthetic methods and uses, the current literature on layered oxides is diverse and disconnected. A number of reviews can be found in the literature, but they are mostly focused on one of the particular subclasses of 2D oxides. This review attempts to bridge the knowledge gap between individual layered oxide types by summarizing recent developments in all important 2D oxide systems including supported ultrathin oxide films, layered clays and double hydroxides, layered perovskites, and novel 2D-zeolite-based materials. Particular attention is paid to the underlying similarities and differences between the various materials, and the subsequent challenges faced by each research community. The potential of layered oxides toward future applications is critically evaluated, especially in the areas of electrocatalysis and photocatalysis, biomass conversion, and fine chemical synthesis. Attention is also paid to corresponding novel 3D materials that can be obtained via sophisticated engineering of 2D oxides.

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Spatial distribution and catalytic performance of metal–acid sites in Mo/MFI catalysts with tunable meso-/microporous lamellar zeolite structures

Cited by 55 publications

References 59 publications

Tuning external surface of unit-cell thick pillared MFI and MWW zeolites by atomic layer deposition and its consequences on acid-catalyzed reactions

Tuning external surface of unit-cell thick pillared MFI and MWW zeolites by atomic layer deposition and its consequences on acid-catalyzed reactions

The distribution of coke formed over a multilayer Mo/HZSM-5 fixed bed in H2 co-fed methane aromatization at 1073 K: Exploration of the coking pathway

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis

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