Effect of the pretreatment temperature on the catalytic activity of ZSM-5 zeolites

Sendoda, Yoko; Ono, Yoshio

doi:10.1016/s0144-2449(88)80073-3

Cited by 58 publications

(22 citation statements)

References 11 publications

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“…With increasing severity of steaming, the apparent rate constant decreases in MFI, indicating that there is an optimum in the activity with steaming. These results are consistent with previous studies on mild steam dealumination of MFI and MOR zeolites [10][11][12][13][14][15][16][17]22,30].…”

Section: Kinetic Parameterssupporting

confidence: 93%

“…In addition to the number of acid sites, it is thought that the strength of the Brønsted acid sites is affected by the acid site density, i.e., the Si/Al ratio [7], the T-O-T bond angle [8,9], the presence of nonframework aluminum [2,3,8,[10][11][12][13][14][15][16][17][18], or charge-balancing cations [18,19]. Theoretical and experimental evidence suggests that the acid strength per aluminum is a maximum when the framework aluminum ions have no second nearest neighbor aluminum [20,21].…”

Section: Introductionmentioning

confidence: 99%

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Observation of a compensation relation for monomolecular alkane cracking by zeolites: the dominant role of reactant sorption

Bokhoven

Williams

et al. 2004

Journal of Catalysis

126

132

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Monomolecular cracking of alkanes was investigated over zeolites of different structure types and after different treatments. Large deviations in apparent rates of reaction and apparent kinetic parameters were detected for zeolites of different structure types; smaller changes were observed within a structure type. The Si/Al ratio and different crystal sizes had no effect on turnover frequency; however, steaming of mordenite and ZSM-5 enhances the rate of reaction by a factor of 2-5 due to the formation of Lewis acid sites with enhanced heat of adsorption, although the number of Brønsted sites decreased. The apparent activation energies and preexponential factors showed a linear compensation relation in a Constable plot. Using the Langmuir-Hinshelwood kinetics formalism, the apparent kinetic parameters include enthalpy and entropy of adsorption and surface reaction terms. If the enthalpy and entropy of adsorption are linearly related, which is experimentally observed for unsteamed and steamed mordenite, then the apparent compensation effect implies that the observed differences in rate are dominated by differences in adsorption of the reactant in the pores of the zeolites, rather than by differences in acid strength. Zeolites with smaller pores show enhanced adsorption, and consequently the rate of reaction increases in the order H-Y < H-MOR < H-ZSM-5.  2004 Elsevier Inc. All rights reserved.

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Section: Kinetic Parameterssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Observation of a compensation relation for monomolecular alkane cracking by zeolites: the dominant role of reactant sorption

Bokhoven

Williams

et al. 2004

Journal of Catalysis

126

132

View full text Add to dashboard Cite

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“…4). [25,26] also reported a similar tendency. In the case of BC 500 , BC 500 B, C 500 and C 500 B, which were all steamed at 500°C, sample BC 500 that has stronger acidity exhibits a higher activity of cracking and aromatization than the other three samples.…”

Section: Product Distribution Of C 4 Lpg Aromatizationsupporting

confidence: 54%

Effect of acidity and diffusibility on coke deactivation over nano-sized HZSM-5 zeolites

Sun

Wang

Li³

et al. 2010

Reac Kinet Mech Cat

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Four series of nano-sized HZSM-5 zeolite catalysts were prepared with different steaming and HNO 3 leaching processes. These samples were studied by XRD, NH 3 -TPD, FT-IR, n-hexane and cyclohexane adsorption, and fixed-bed aromatization of C 4 liquefied petroleum gas (C 4 LPG). Results show that, with the steaming temperature increasing, the acidity of catalyst decreased gradually, which was attributed to the removal of Al species from the framework of the zeolite. When steaming is combined with acid leaching, we found that acid leaching-steam catalysts exhibit stronger acidity than steam-acid leaching catalysts. Besides, acid leaching also played an important role in enhancing the diffusibility of catalysts. Catalysts which underwent acid leaching twice exhibit the best microporous diffusibility. Through correlating the acidity and diffusibility of the catalysts with their aromatization performance, it is found that the product distribution of aromatization is mainly determined by catalyst acidity rather than diffusibility. On the other hand, the average coking speed of the catalysts is not only influenced by the acidity of the catalyst, but also by its microporous diffusibility. The improvement of microporous diffusibility remarkably favors suppressing the coking deactivation of nano-sized ZSM-5 zeolite in C 4 LPG aromatization.Electronic supplementary material The online version of this article (

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“…Besides microporous structure, mesoporous structure from the inorganic oxide matrix, SiO 2 -Al 2 O 3 , which provides physical strength and heat or mass transfer was also observed in nitrogen physical adsorption measurement. Hydrothermal treatment has been widely used in industry [10][11][12]. Steaming at high temperature usually leads to dealumination of zeolite with the formation of dislodged aluminum which remains in the zeolite channel.…”

Section: Morphology Crystalline and Porositymentioning

confidence: 99%

A ZSM-5-based Catalyst for Efficient Production of Light Olefins and Aromatics from Fluidized-bed Naphtha Catalytic Cracking

et al. 2008

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A ZSM-5-based catalyst was prepared by spraydry method for fluidized-bed naphtha catalytic cracking. Multi-techniques, such as X-ray diffraction, scanning electron microscope, 27 Al MAS NMR, and NH 3 -TPD, were employed for the investigation of ZSM-5 framework stability, framework dealumination, and catalyst acidity variation in hydrothermal treatment. Catalytic performances of fluidizedbed naphtha catalytic cracking at 630-680°C indicated that light olefins and other value-added products could be more efficiently produced compared with the commercial process of thermal steam cracking. Long-term catalytic evaluation implied that naphtha catalytic cracking over the catalyst prepared with spray-dry method and hydrothermal treatment can be carried out at a variable reaction condition with a relatively high and stable light olefins yield.

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Effect of the pretreatment temperature on the catalytic activity of ZSM-5 zeolites

Cited by 58 publications

References 11 publications

Observation of a compensation relation for monomolecular alkane cracking by zeolites: the dominant role of reactant sorption

Observation of a compensation relation for monomolecular alkane cracking by zeolites: the dominant role of reactant sorption

Effect of acidity and diffusibility on coke deactivation over nano-sized HZSM-5 zeolites

A ZSM-5-based Catalyst for Efficient Production of Light Olefins and Aromatics from Fluidized-bed Naphtha Catalytic Cracking

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