Direct and selective conversion of methanol to para-xylene over Zn ion doped ZSM-5/silicalite-1 core-shell zeolite catalyst

Miyake, Koji; Hirota, Yuichiro; Ono, Kaito; Uchida, Yoshiyuki; Tanaka, Shunsuke; Nishiyama, Norikazu

doi:10.1016/j.jcat.2016.07.008

Cited by 119 publications

(76 citation statements)

References 52 publications

(38 reference statements)

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“…Ion exchange of HSZ:S ynthesized HSZ (1.0 g) was added into NH 4 Cl solution (100 mL;1m)a nd stirred at 80 8Cf or 4h.T his procedure was repeated 3times. Then, ion-exchanged samples were dried and calcined at 550 8Cf or 4h to make the catalysts be Htype.…”

Section: Materials Preparationmentioning

confidence: 99%

“…To increase selectivity towards para ‐isomer, catalysts with excellent shape‐selectivity are indispensable. In this respect, ZSM‐5 zeolites are well known and promising candidates because of its 10‐membered ring (MR) pore system with MFI topography, the size of which is comparable to p ‐X molecules . On the other hand, the sole presence of microporous structure in purely ZSM‐5 zeolites often leads to mass‐transfer limitations, and the internal acid sites of ZSM‐5 cannot be utilized adequately.…”

Section: Introductionmentioning

confidence: 99%

“…In this respect, ZSM-5 zeolites are well known and promising candidates because of its 10-membered ring (MR) pore system with MFI topography,t he size of which is comparable to p-X molecules. [4] On the other hand, the sole presence of microporous structure in purely ZSM-5 zeoliteso ften leads to mass-transfer limitations, and the internal acid sites of ZSM-5c annot be utilized adequately.A saresult, its catalytic activity in bulky aromatic transformations is far from being satisfactory. Besides, the micropores of ZSM-5 will easily be blockedb y coking, which could cause rapid catalystd eactivation.…”

Section: Introductionmentioning

confidence: 99%

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Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Hua

Zhou

et al. 2018

ChemCatChem

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Hierarchically structured ZSM‐5 zeolites (HSZ) were synthesized and used as high‐performance catalysts for para‐xylene (p‐X) production by tuning their pore structures and external surface acidity, which was achieved by two independent passivation approaches: dealumination in oxalic acid solution and chemical liquid deposition of tetra‐ethoxysilane (CLD of TEOS). The mesoporous structures of HSZ were well‐preserved after dealumination or CLD of TEOS, and the external surfaces of HSZ were passivated significantly. Compared to dealumination, CLD is more efficient because not only the external surface could be passivated, but also the pore‐openings of HSZ had been effectively narrowed, which both favored the enhancement of product p‐X selectivity in ortho‐xylene (o‐X) isomerization. The constraint index (CI) of as‐synthesized catalysts derived from the competitive reactions of ethylbenzene (EB) dealkylation and meta‐xylene (m‐X) isomerization and gravimetric adsorption measurements were introduced to investigate the extent of pore‐narrowing by CLD of TEOS. Benefitting from the auxiliary mesopores and surface‐passivation treatments, the optimized catalyst HSZ(Si0.5) showed remarkably enhanced catalytic activity over the microporous ZSM‐5 counterpart in the model reaction of o‐X isomerization.

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Section: Materials Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Hua

Zhou

et al. 2018

ChemCatChem

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“…[1][2][3] HZSM-5 zeolite is regarded as the most appropriate catalytic-material for this process, because of its adjustable acidic properties, high hydrothermal stability and regular three-dimensional 10-ring pore matching with the light aromatic molecules. [1][2][3] HZSM-5 zeolite is regarded as the most appropriate catalytic-material for this process, because of its adjustable acidic properties, high hydrothermal stability and regular three-dimensional 10-ring pore matching with the light aromatic molecules.…”

Section: Introductionmentioning

confidence: 99%

Insight into the Formation of CO_X By‐Products in Methanol‐to‐Aromatics Reaction over Zn/HZSM‐5: Significantly Affected by the Chemical State of Surface Zn Species

Gong

Liu

et al. 2019

ChemCatChem

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Several Zn-modified HZSM-5 catalysts prepared by impregnation or ion exchange were characterized, and tested in methanol-to-aromatics (MTA) reaction. The obviously enhanced output of CO X by-products (CO & CO 2 ) was observed over these modified catalysts, although they showed the significantly improved selectivity of aromatics. It was found CO X formation is actually determined by the chemical state of surface Zn species. Concretely, both surface ZnO and surface metal-zinc are the reactive sites for the conversion of methanol to CO X and H 2 . At the initial period of reaction, surface ZnO (no reduction) causes CO X (mainly CO 2 ) formation may almost-exclusively through methanol steam-reforming. With the extending of reactiontime, while it's partially reduced to metal-zinc which more violently catalyzes the conversion of methanol to CO X (both CO and CO 2 ) may through the pathway of first dehydrogenationdecomposition and subsequent Water-Gas-Shift reaction. However, the surface ZnOH + species as Lewis acid hardly results in CO X formation, but significantly promotes aromatization due to its interaction-dehydrogenation effect. As high as possible ratio of the ZnOH + in surface Zn species is conducive to both suppressing the side-reaction which produces CO X and incubating the high aromatic selectivity even in the time-on-stream reaction. Our work may provide a theoretical guidance for developing the elegant catalyst for the MTA process with high carbon atom utilization.[a] Dr.

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“…Zeolite is widely known for its application in particular fields such as sorption [1], catalysis [2,3] and ion-exchange [4]. Recently, its use has been extended to wider applications, including optical [5] and membrane technology [6].…”

Section: Introductionmentioning

confidence: 99%

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

et al. 2016

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Abstract. Zeolite ZSM-5 is one of the major catalysts in the petroleum and finechemical industries. The synthesis of zeolite ZSM-5 is usually carried out at a temperature above 100 °C using an immense amount of organic structuredirecting agents (OSDA). It is interesting to note that fine-tuning the initial gel mixture can be used to enhance the typical slow crystallization rate of ZSM-5. Herein, we report the effect of the surface-to-volume ratio of the reactor vessel on the crystallization of ZSM-5 at low temperature. The surface-to-volume ratio of the reactor vessel influences the heat-transfer during the synthesis, which further governs the crystallization of ZSM-5. It was found that the higher the surface-to-volume of the reactor, the more crystalline the resulting product. The products with the highest crystallinity exhibited a nearly spherical morphology composed of smaller ZSM-5 crystallites. This phenomenon allows the presence of inter-crystallite mesopores, which is an advantage for the catalytic reaction of bulky molecules. Keywords: low OSDA; low temperature; mesopores; surface-to-volume ratio; ZSM-5. IntroductionZeolite is a class of crystalline microporous (< 2 nm) aluminosilicate materials, arranged in a long-range order by TO4 (T = Si or Al) units. Zeolite is widely known for its application in particular fields such as sorption [1], catalysis [2,3] and ion-exchange [4]. Recently, its use has been extended to wider applications, including optical [5] and membrane technology [6]. Catalysis is the most known application of zeolite, for instance ZSM-5, especially for boosting the octane number in fluid catalytic cracking (FCC) units [7]. This is due to its peculiar structure comprising straight and zig-zag channels within sizes of around 5.5 Å and the presence of strong acid sites.

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Direct and selective conversion of methanol to para-xylene over Zn ion doped ZSM-5/silicalite-1 core-shell zeolite catalyst

Cited by 119 publications

References 52 publications

Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Insight into the Formation of CO_X By‐Products in Methanol‐to‐Aromatics Reaction over Zn/HZSM‐5: Significantly Affected by the Chemical State of Surface Zn Species

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

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Direct and selective conversion of methanol to para-xylene over Zn ion doped ZSM-5/silicalite-1 core-shell zeolite catalyst

Cited by 119 publications

References 52 publications

Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Surface‐Passivated Hierarchically Structured ZSM5 Zeolites: High‐Performance Shape‐Selective Catalysts for para‐Xylene Production

Insight into the Formation of COX By‐Products in Methanol‐to‐Aromatics Reaction over Zn/HZSM‐5: Significantly Affected by the Chemical State of Surface Zn Species

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

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Insight into the Formation of CO_X By‐Products in Methanol‐to‐Aromatics Reaction over Zn/HZSM‐5: Significantly Affected by the Chemical State of Surface Zn Species