On the nature of the sites responsible for the enhancement of the cracking activity of HZSM-5 zeolites dealuminated under mild steaming conditions: Part 2

Zholobenko, Vladimir L.; Kustov, L. М.; Kazansky, V.B.; Loeffler, E.; Lohse, U.; Oehlmann, G.

doi:10.1016/0144-2449(91)80406-p

Cited by 51 publications

(20 citation statements)

References 4 publications

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“…The integral intensity of the peak observed at ca. 1455 cm −1 is used for estimating the concentration of Lewis acid site [17,18]. The detected integral intensity of the IR band at ca.…”

Section: Resultsmentioning

confidence: 99%

Acidic sites in beta zeolites in dependence of the preparation methods

Dimitrova

Gündüz

Dimitrov

et al. 2004

Journal of Molecular Catalysis A: Chemical

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Beta zeolites synthesized by different methods are compared in their structure peculiarities and acidic properties by nitrogen physisorption, IR-KBr, pyridine sorption-desorption and thermoprogrammed desorption of ammonia. It is found that mesopores could be obtained in beta zeolites with the change of the activation procedure. Methanol conversion to dimethyl ether and hydrocarbons is used as a test reaction for understanding of the acid center function.

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“…The integral intensity of the peak observed at ca. 1455 cm −1 is used for estimating the concentration of Lewis acid site [17,18]. The detected integral intensity of the IR band at ca.…”

Section: Resultsmentioning

confidence: 99%

Acidic sites in beta zeolites in dependence of the preparation methods

Dimitrova

Gündüz

Dimitrov

et al. 2004

Journal of Molecular Catalysis A: Chemical

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“…[38] Moreover, high O/P molar ratios (1.5-1.7) could be related to hydride abstraction induced by Lewis acid sites. [39][40] Yet, the presence of these "super-acid" sites has been contested by Iglesia and co-workers, [41] who suggested that the apparent increased BAS strength would not result from electronic interactions with EFAL species, but rather from a higher solvation effect of the zeolite voids attributable to the occlusion of the void space by extra-framework Al residues. This reasoning is questionable through comparing the TOF values of n-hexane cracking obtained by MFI (i.e.…”

Section: Chemical Propertiesmentioning

confidence: 99%

Pyridine assisted desilication of mordenite

Issa

Toufaily

Hamieh

et al. 2019

Applied Catalysis A: General

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Pyridine assisted alkaline desilication has been elaborated as new post-synthetic modification strategy of mordenite. The addition of pyridine during the desilication treatment revealed to impact materials properties through a dual action on textural and chemical properties; substantially different in comparison to the classical alkaline treatment or CTAB assisted desilication. As far as texture is concerned the use of pyridine permits to greatly modify the desilication scheme, hence yielding aggregates of smaller zeolite particles with substantially higher amount of external silanols. The presence of pyridine in the as-synthesized mordenites allows to in situ generate extra-framework aluminium (EFAL) species during final calcination step. Both of these features, smaller particle size and the presence of EFAL species improve catalytic properties considerably. Whilst the achievement of smaller particles reduces diffusion path length, the presence of EFAL species allow for exalting acidity and hence catalytic activity in n-hexane cracking and propene transformation.

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“…e addition of Si +4 with P +5 results in the formation of Bronsted acid sites, which makes these molecules more selective as catalyst for specific reaction [55][56][57][58][59][60][61][62][63][64][65][66][67]. Among the various SAPOs, SAPO-34 has a good selectivity to ethylene and propylene.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Effective Parameters Ce and Zr in the Synthesis of H-ZSM-5 and SAPO-34 on the Production of Light Olefins from Naphtha

Aldeen

Mahmoud

Majdi³

et al. 2022

Advances in Materials Science and Engineering

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In this paper, Ce and Zr modified commercial SAPO-34 and H-ZSM-5 catalysts were synthesized via a wet impregnation method and used as catalysts for the production of light olefins from naphtha. The synthesized catalysts were characterized using SEM, TGA, XRD, BET, and NH3-TPD. Thermal catalytic cracking of parent catalysts (SAPO-34 and H-ZSM-5) and modified catalysts with Ce and Zr on the production of light olefins from naphtha has been studied. The effects of different loading of Ce (2–8 wt.%), Zr (2–5 wt.%), and different temperatures on the yield of ethylene and propylene were also investigated. The yield of ethylene and propylene improved by 21.78 wt% and 23.8 wt%, respectively, over 2% Ce and 2% Zr on SAPO-34 catalyst. This is due to the higher acid sites on the surface of modified catalysts. It was found that H-ZSM-5 with 2% Zr loading has the highest yield of light olefins (40.4%) at 650°C in comparison with unmodified parent catalysts, while Ce loading has less effect on the olefin yield compared to Zr loading. Finally, simultaneous loading of Ce and Zr showed no effect on the light olefin yield owing to the significant decline of acid sites.

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On the nature of the sites responsible for the enhancement of the cracking activity of HZSM-5 zeolites dealuminated under mild steaming conditions: Part 2

Cited by 51 publications

References 4 publications

Acidic sites in beta zeolites in dependence of the preparation methods

Acidic sites in beta zeolites in dependence of the preparation methods

Pyridine assisted desilication of mordenite

Investigation of Effective Parameters Ce and Zr in the Synthesis of H-ZSM-5 and SAPO-34 on the Production of Light Olefins from Naphtha

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