Mild-acid-assisted thermal or hydrothermal dealumination of zeolite beta, its regulation to Al distribution and catalytic cracking performance to hydrocarbons

Wang, Wennian; Zhang, Wei; Chen, Yunlei; Wen, Xiaodong; Li, Hao; Yuan, Delin; Guo, Qiaoxia; Ren, Shenyong; Pang, Xinmei; Shen, Baojian

doi:10.1016/j.jcat.2018.03.002

Cited by 64 publications

(30 citation statements)

References 70 publications

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“…The decrease in the intensity of all the peaks of the sample ZO3 also can be explained by extracting the aluminum from the zeolite framework which leads to the decrease in the crystallinity. These results are consistent with those obtained in the literature [47,48]. According to the literature, acid treatment leads essentially to the elimination of most of tetrahedral extra framework aluminum.…”

Section: Characterization Of Adsorbents X-ray Diffractionsupporting

confidence: 93%

Structural, textural and toluene adsorption properties of microporous–mesoporous zeolite omega synthesized by different methods

Mekki

Boukoussa

2019

J Mater Sci

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This work deals with the preparation of the zeolite omega using hydrothermal route. This zeolite was modified by acidic, basic and hydrothermal treatment (at 100°C and 150°C) using a basic/CTA ? solution. The modified zeolites were characterized by X-ray diffraction, adsorption/desorption of argon, Fourier transform infrared spectroscopy, thermogravimetric analysis TGA and scanning electronic microscopy. The obtained materials were tested for the adsorption of toluene at ambient temperature. The results showed that the zeolites modified by basic treatment showed the highest mesoporosity (* 166 Å ) and the low specific surface area and pore volume, while the one treated with an acid (dealuminated) showed a mesoporosity of * 30 Å and a higher specific surface area and porous volume. The hydrophilic character was improved after the different treatments compared to the parent material, in which the dealuminated zeolite showed the highest hydrophilic character. All modified zeolites showed a good affinity via the adsorption of toluene, and the best adsorption capacity was obtained by dealuminated zeolite. Compared to the unmodified zeolite omega (parent sample), an improvement of 68% of adsorption capacity was obtained. Finally, the dealuminated zeolite showed good stability during reuse for five cycles without loss of its adsorption capacity.

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Section: Characterization Of Adsorbents X-ray Diffractionsupporting

confidence: 93%

Structural, textural and toluene adsorption properties of microporous–mesoporous zeolite omega synthesized by different methods

Mekki

Boukoussa

2019

J Mater Sci

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“…The asymmetrical stretching vibration of the T−O−T framework at 1084 cm −1 for the parent catalyst (HSi@BEA) shifted to 1090 cm −1 for the N/HSi@BEA catalyst, suggesting framework dealumination. 37,60 The P/HSi@BEA catalyst showed a slight shift in the v TOT value (1086 cm −1 ) from the parent catalyst, which indicates that some aluminum atoms are hard to remove due to high stability, and only a few Al atoms were removed to give EFAl. 37 Deconvolution of the FTIR spectrum of HSi@BEA, P/ HSi@BEA, and N/HSi@BEA catalysts in the 3800−3400 cm −1 range by Gaussian curve-fitting (Figure 6A) showed that the spectrum consisted of eight bands at 3780, 3740, 3720, 3690, 3665, 3610, 3550, and 3480 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

“…The shift in the corresponding peak specified the dealumination of the catalyst framework. 37−39 Shifting of 2θ = 22.46°for the parent beta to 2θ = 22.50°for hydrochloric acid treatment, followed by steaming of the beta catalyst, was claimed due to dealumination of the catalyst framework, as conveyed by Wang et al 37 The disturbance of the parent framework was most probably due to the acid treatment during the impregnation of phosphate and nitrate groups on the catalyst, which could affect the extra-framework aluminum species (EFAl). 14,17,40 Zhao et al revealed that after modification of HZSM-5 with phosphoric acid, the structure and acidity of the catalyst were affected due to the extraction of tetrahedral aluminum in the catalyst framework to the extraframework.…”

Section: Methodsmentioning

confidence: 99%

“…4,21 However, a new peak appeared at −5.8 ppm for the N/HSi@BEA catalyst, which is attributed to the distorted octahedral Al species. 37 This was probably due to the interaction of the nitrate group with some extra-framework Al. Thus, we can summarize that the amount of EFAl species present in all catalysts is in the following order: HSi@BEA > N/HSi@BEA > P/HSi@BEA.…”

Section: Methodsmentioning

confidence: 99%

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Influence of Nitrate and Phosphate on Silica Fibrous Beta Zeolite Framework for Enhanced Cyclic and Noncyclic Alkane Isomerization

et al. 2020

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Phosphate and nitrate were loaded on silica BEA (P/HSi@BEA and N/HSi@BEA), which is fibrously protonated by the impregnation method for n-hexane and cyclohexane isomerization. The characterization analysis specified the removal of tetrahedral aluminum atoms in the framework, which was triggered by the existence of phosphate and nitrate groups in the catalyst. The exchanged role of Si(OH)Al to P–OH as active acidic sites in the P/HSi@BEA catalyst reduced its acidic strength, which was confirmed by the FTIR results. Lewis acidic sites of P/HSi@BEA performance are a significant part in the generation of high protonic acid sites, as proven by the in situ ESR study. However, FTIR evacuation and 27Al NMR revealed that the reduction in the amount of extraframework Al (EFAl) is due to its interaction with the nitrate group on the outside of the catalyst surface. The N/HSi@BEA catalyst exhibited high acidic strength because of the existence of more Si(OH)Al, which was initiated during the nitrate-incorporation process. Of significance is that the catalytic performance of n-hexane isomerization in the presence of hydrogen reached 50.3% product isomer yield at 250 °C, which might be ascribed to the presence of P–OH active sites that are responsible for accepting electrons, forming active protonic acid sites. NO3–EFAl interaction induced the formation of Brønsted acid sites, and higher mesopore volume favors the production of cyclohexane isomers up to 48.4% at 250 °C. This fundamental study exhibits that significant interactions given by such phosphate and nitrate groups with the unique silica fibrous BEA support could enhance isomerization, which contributes to the high quality of fuel.

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“…FT-IR spectra were recorded on a Thermo Fisher Nicolet IS50 spectrometer to obtain the characteristic peak of samples. Self-supporting wafers with a mass ratio of 1:80 for the sample and KBr mixture were prepared [13]. The spectrum was collected at room temperature in air at 0.482 cm -1 resolution.…”

Section: Characterizationmentioning

confidence: 99%

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Cen¹,

Yang²,

Zhu³

et al. 2021

MSCE

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Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600˚C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.

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Mild-acid-assisted thermal or hydrothermal dealumination of zeolite beta, its regulation to Al distribution and catalytic cracking performance to hydrocarbons

Cited by 64 publications

References 70 publications

Structural, textural and toluene adsorption properties of microporous–mesoporous zeolite omega synthesized by different methods

Structural, textural and toluene adsorption properties of microporous–mesoporous zeolite omega synthesized by different methods

Influence of Nitrate and Phosphate on Silica Fibrous Beta Zeolite Framework for Enhanced Cyclic and Noncyclic Alkane Isomerization

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

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