Improvement in the catalytic properties of ZSM-5 zeolite nanoparticles via mechanochemical and chemical modifications

Inagaki, Shigenori; Shinoda, Shoma; Hayashi, Shunsuke; Wakihara, Toru; Yamazaki, Hiroshi; Kondo, Junko N.; Kubota, Yoshihiro

doi:10.1039/c5cy01644d

Cited by 36 publications

(22 citation statements)

References 36 publications

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“…All the above analyses strongly confirm that the internal acid sites are the main active sites for the monomolecular cracking reaction, whereas the external acid sites are the dominant position for undesirable bimolecular reactions such as alkylation, hydrogen transfer, and isomerization because of less space constraint . In the presence of external acid sites, the primary products such as ethylene and propylene can undergo further reactions that lead to the formation of coke precursors (benzene, toluene, and xylenes) and the coke deposits, as proposed in Scheme . This suggests that, even though the mesoporous structure is of great importance to decrease the diffusion resistance to obtain more ethylene and propylene compared with the solely microporous zeolites, the external acid sites impede further generating even more light olefins.…”

Section: Resultsmentioning

confidence: 99%

The Role of External Acidity of Hierarchical ZSM‐5 Zeolites in n‐Heptane Catalytic Cracking

et al. 2018

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The hierarchical ZSM‐5 zeolite, which contains mesopores in addition to intrinsic micropores, is expected to enhance the bulky molecular diffusion and accessibility of acid sites. These sites, distributed in the internal surface (micropore) or external environment (including external surface and mesopore walls), play different roles in chemical reactions. To explore the effect of internal/external acidity on the reaction, in this study, a series of hierarchical ZSM‐5 zeolites with similar pore structures but different external acid properties were synthesized. Tartaric acid was employed to poison the acidic sites in the external environment selectively and extract Al from the framework. The catalytic cracking of n‐heptane (the main compound of naphtha) was chosen as a model reaction. The results show that elimination of external active sites tends to reduce the coke formation. The more external acid sites are selectively eliminated, the better catalytic performance can be achieved because of suppressing the bimolecular reactions of ethylene and propylene.

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Section: Resultsmentioning

confidence: 99%

The Role of External Acidity of Hierarchical ZSM‐5 Zeolites in n‐Heptane Catalytic Cracking

et al. 2018

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“…6). [96][97][98][99][100] This methodology was also employed for SAPO-34, recrystallised from either a freshly prepared aluminosilicate solution or the mother liquor of the original synthesis. 101 A more concise procedure was presented as an in situ milling and recrystallisation method, using highly alkaline solutions during the milling procedure.…”

Section: Mechanochemically Assisted Recrystallisationmentioning

confidence: 99%

New avenues for mechanochemistry in zeolite science

Rainer

Morris

2021

Dalton Trans.

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“…Thus, in this case, seed crystals after the milling worked as the source of units. It is known that zeolites after a mechanochemi‐cal treatment have defects that accelerate recrystallization of zeolites . Therefore, in our synthesis method, units of zeolite could be formed by the ball milling and uniformly dis‐persed in the aluminosilicate composite, which would contrib‐ute to the crystallization of ZSM‐5.…”

Section: Figurementioning

confidence: 99%

Solvent- and OSDA-Free Synthesis of ZSM-5 Assisted by Mechanochemical and Vapor Treatments

et al. 2017

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Various synthesis methods of zeolites have been established. Hydrothermal synthesis method with organic structure directing agent (OSDA) has been widely applied in zeolite synthesis. However, this method has some big problems in terms of industrial and environmental aspects: OSDA is expensive and thermally decomposed OSDA produces air pollution; and the yield of zeolite crystals per reactor volume is low due to the presence of solvent. We hence synthesized ZSM‐5 (MFI‐type zeolite) in the absence of both solvent and OSDA to overcome these problems. Briefly, the starting materials including silica powder, sodium aluminate, sodium hydroxide and a small amount of seed crystals (ZSM‐5) were mixed together and grinded using a ball mill. Then the milled powder was crystallized under a steam atmosphere by varying crystallization time. We found that an MFI phase started to appear after 12 h and the formation of pure ZSM‐5 crystals was completed after 24 h. Our method provides a simpler and efficient process of zeolite synthesis in an environment‐friendly manner than those of any conventional solvent methods, which will promise to promote mass production of a variety of zeolites.

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Improvement in the catalytic properties of ZSM-5 zeolite nanoparticles via mechanochemical and chemical modifications

Abstract: A combination of bead-milling, subsequent recrystallization and acid treatment of micron-sized ZSM-5 zeolite can provide a highly efficient ZSM-5 nanoparticle catalyst.

Cited by 36 publications

References 36 publications

The Role of External Acidity of Hierarchical ZSM‐5 Zeolites in n‐Heptane Catalytic Cracking

The Role of External Acidity of Hierarchical ZSM‐5 Zeolites in n‐Heptane Catalytic Cracking

New avenues for mechanochemistry in zeolite science

Solvent- and OSDA-Free Synthesis of ZSM-5 Assisted by Mechanochemical and Vapor Treatments

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