Comparison of surface passivation modification of two mordenite zeolites and their application on the isomerisation of <i>o</i>-ethyltoluene

Cao, Xiaoyan; Wang, Kaijun; Kong, Lingxin; Gu, Zhenggui; Wang, Fang

doi:10.1039/d2ra05390j

Cited by 4 publications

(5 citation statements)

References 37 publications

(54 reference statements)

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“…This issue has been elucidated in several studies, including that of Cao et al, 19 wherein they showed that passivating a MOR zeolite via chemical vapor deposition of TEOS resulted in pore blockage, leading to accelerated deactivation during the isomerization reaction of o -ethyltoluene. Other studies, such as the one analyzed in the review by Xu et al, 20 have demonstrated the importance of controlling the silylation level and finding a volcano-plot for the amount of SiO 2 to be deposited.…”

Section: Discussion and Future Outlookmentioning

confidence: 99%

“…Cao et al 19 emphasized the effect of CLD of TEOS on the textural properties of MOR, indicating that this method could shrink and block the microporous channels of the zeolite. For comparison, the authors also used 3,5-dimethylphenylmagnesium bromide (DPB) as a bulk precursor to passivate the external surface of the crystals with MgO, claiming that both the passivating molecules, i.e., TEOS and DPB, are not able to access the 12 MR channels of MOR.…”

Section: Chemical Neutralizationmentioning

confidence: 99%

Section: Zeolite Surface Passivation and Catalysismentioning

confidence: 99%

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Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Ferrarelli,

Migliori,

Catizzone

2024

ACS Omega

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Zeolites are crystalline aluminosilicates with well-defined microporous structures that have found several applications in catalysis. In recent years, great effort has been devoted to defining strategies aimed at tuning structural and acidity properties to improve the catalytic performance of zeolites. Depending on the zeolitic structure, the acid sites located inside the crystals catalyze reactions by exploiting the internal channel shape-selectivity. In contrast, strong acid sites located on the external surface do not offer the possibility to control the size of molecules involved in the reactions. This aspect generally leads to a loss of selectivity toward desired products and to the uncontrolled production of coke. Passivating surface acidity is a promising way to overcome deactivation issues and to enhance the catalytic performance of zeolites. This Mini-Review aims to provide, for the first time, a complete overview of the techniques employed in recent years to neutralize strong external acid sites. Both chemical and liquid vapor deposition of silicates have been widely employed to passivate the external surface acidity of zeolites. In recent years, the epitaxial growth of layers of aluminum-free zeolite, e.g., silicalite-1, over the surface of the acidic zeolite has been proposed as a new approach to neutralize strong external acid sites controlling diffusional phenomena. NH 3 -TPD, FT-IR, SEM-EDX, and other techniques have been used to provide information about the level of control of the external strong acidity of passivated zeolites. In this Mini-Review, both passivation treatments and characterization techniques are compared and advantages and disadvantages deeply discussed to elucidate the effect of passivation procedures on physical features and especially the catalytic behavior.

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Section: Discussion and Future Outlookmentioning

confidence: 99%

Section: Chemical Neutralizationmentioning

confidence: 99%

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Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Ferrarelli,

Migliori,

Catizzone

2024

ACS Omega

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“…Mordenite is one of the several zeolites that have been industrially applied, such as in isomerization, , alkylation, − toluene disproportionation, etc. MOR exhibits large 12-membered ring (12-MR) channels along the c -axis, which are intersected by 8-MR channels along the b- axis .…”

Section: Introductionmentioning

confidence: 99%

“…19 It is believed that the existence of seeds facilitates nucleation; thus, more primary particles and smaller zeolite crystals were formed in the seedassisted process. 20,21 Mordenite is one of the several zeolites that have been industrially applied, such as in isomerization, 22,23 alkylation, 24−26 toluene disproportionation, 27 etc. MOR exhibits large 12-membered ring (12-MR) channels along the c-axis, which are intersected by 8-MR channels along the b-axis.…”

Section: Introductionmentioning

confidence: 99%

Wheel-like Mordenite Nanoassemblies with Shortened Channel Lengths for Improved Catalytic Performance in Dimethyl Ether Carbonylation

Liu,

Wang,

et al. 2023

ACS Appl. Nano Mater.

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To achieve a better catalytic performance, it is of great interest to synthesize nanosized zeolites with reduced internal diffusion limitations. Herein, c-axis shortened wheel-like mordenite nanoassemblies were synthesized. The crystal growth along the [001] direction was successfully inhibited with K + cations as structure breaking agents. The wheel-like crystal is 1.5−2 μm in diameter and 200−300 nm in thickness. The growth of such a unique structure underwent a nonclassical crystallization process including the generation of amorphous worm-like particles and formation of wheel-like crystallites followed by a−b plane oriented growth of the crystals. The obtained MOR wheel-like assemblies possessed larger surface area and external surface area, displayed better mass transfer properties, and exhibited much better catalytic performance than MOR spheroid-like assemblies and conventional bulk MOR zeolite in dimethyl ether (DME) carbonylation reaction, with two and a half times higher the conversion of DME than the bulk MOR, although these samples had identical Si/Al ratios and acid properties. This work provides a simple route to control the zeolite morphology by alkali metal cations and brings forward an effective strategy to prepare zeolite materials with improved catalytic performance.

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Optimizing host–guest selectivity through side-chain modification of pillar[6]arenes for o-ethyltoluene/m-ethyltoluene separation

Liu,

Fang,

Shao

et al. 2024

Microporous and Mesoporous Materials

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Comparison of surface passivation modification of two mordenite zeolites and their application on the isomerisation of o-ethyltoluene

Abstract: During the isomerisation of o-ethyltoluene (O-ET) to produce m-ethyltoluene (M-ET) and p-ethyltoluene (P-ET), it is crucial to improve the isomerisation selectivity and reduce side reactions, such as disproportionation, alkyl transfer, and splitting.

Cited by 4 publications

References 37 publications

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Wheel-like Mordenite Nanoassemblies with Shortened Channel Lengths for Improved Catalytic Performance in Dimethyl Ether Carbonylation

Optimizing host–guest selectivity through side-chain modification of pillar[6]arenes for o-ethyltoluene/m-ethyltoluene separation

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