Desilication of ZSM-5 and ZSM-12 Zeolites with Different Crystal Sizes: Effect on Acidity and Mesoporous Initiation

Silva, Lidiane Sabino da; Araki, Carina Akemi; Marcucci, Sílvio Miguel Parmegiani; Silva, Victor Luis dos Santos Teixeira da; Arroyo, Pedro Augusto

doi:10.1590/1980-5373-mr-2018-0872

Cited by 22 publications

(12 citation statements)

References 36 publications

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“…This shows that the electrostatic repulsion of Mg 2+ by the membrane was much higher than that of Na + , hence why the high rejection of MgCl 2 was observed. It can be concluded that the composite membranes in this study possess negatively charge surfaces due to the AlO 4 tetrahedra interactions with the SiOH of ZSM-22 nanoadditives [ 84 , 86 , 87 ].…”

Section: Resultsmentioning

confidence: 99%

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

2020

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ZSM-22/polyethersulfone membranes were prepared for salt rejection using modelled brackish water. The membranes were fabricated via direct ZSM-22 incorporation into a polymer matrix, thereby inducing the water permeability, hydrophilicity and fouling resistance of the pristine polyethersulfone (PES) membrane. A ZSM-22 zeolite material with a 60 Si/Al ratio, high crystallinity and needle-like morphologies was produced and effectively used as a nanoadditive in the development of ZSM-22/PES membranes with nominal loadings of 0–0.75 wt.%. The characterisation and membrane performance evaluation of the resulting materials with XRD, BET, FTIR, TEM, SEM and contact angle as well as dead-end cell, respectively, showed improved water permeability in comparison with the pristine PES membrane. These ZSM-22/PES membranes were found to be more effective and superior in the processing of modelled brackish water. The salt rejection of the prepared membranes for NaCl and MgCl2 was effective, while they exhibited quite improved water flux and flux recovery ratios in the membrane permeability and anti-fouling test. This indicates that different amounts of ZSM-22 nanoadditives produce widely divergent influences on the performance of the pristine PES membrane. As such, over 55% of salt rejection is observed, which means that the obtained membranes are effective in salt removal from water.

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Section: Resultsmentioning

confidence: 99%

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

2020

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“…During the desilication process, the uncontrolled degradation of the zeolite structure does not occur and other mesoporous parts with a wide pore size distribution formed in the sample. Furthermore, this justifies the occurrence of the characteristic isotherms of microporous materials in both the parent and alkali-treated samples (Ahmadpour and Taghizadeh 2015b;Gorzin et al 2019a;Sabino da Silva et al 2019;Pérez-Ramírez et al 2009).…”

Section: Textural Properties and Morphologymentioning

confidence: 70%

Preparation of hierarchical H-[B]-ZSM-5 zeolites by a desilication method as a highly selective catalyst for conversion of methanol to propylene

Beheshti

Ahmadpour

Behzad

et al. 2020

Braz. J. Chem. Eng.

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A hydrothermal route was exploited to prepare high-silica H-ZSM-5 as well as H-[B]-ZSM-5 zeolites, and the boron-modified type was then desilicated with alkaline treatment. The properties of catalysts were investigated by different techniques, and the catalytic performance was evaluated in the methanol to propylene reaction. The effects of three critical desilication parameters, including the alkali concentration, temperature, and treatment time were evaluated on propylene selectivity and mesopore volume. The results of characterizations evinced that the incorporation of B in the H-ZSM-5 zeolite reduced the total surface area as well as the pore volume of the H-[B]-ZSM-5 sample and increased the external surface area. Furthermore, a significant increase in the weak acid site density for the boron-containing specimen was observed. Also, the external surface area and mesopore volume of the desilicated specimens underwent an increment, while the micropore volume was almost constant. As opposed to the H-[B]-ZSM-5 catalyst, the optimum desilicated catalyst exhibited higher selectivity to propylene (48.8 vs. 40.7%) and total light olefins (76.9 vs. 71.2%), and a higher ratio of propylene to ethylene (5.66 vs. 4.15). The optimum catalyst had a higher lifetime in the MTP reaction (867 h) as opposed to the microporous H-[B]-ZSM-5 catalyst (498 h).

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“…Similarly, in the desilication method, along with 1.0 g of parent material, 30 ml of (0.1 mol/L) sodium hydroxide solution was added in a round bottom flask and refluxed at 323 ℃ for 1 hour [60]. The base treated sample was collected after the treatment and centrifuged to wash with deionised water repeatedly till neutral pH in the filtrate was observed.…”

Section: Base Treatment (Desilication Method)mentioning

confidence: 99%

Liquid-phase Alkylation of Toluene by Benzyl Alcohol over Micro-mesoporous Hierarchical Mordenite Zeolite

Bandopadhyay

Koshti

2023

Preprint

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In this work, post-synthetic effective acid (HNO3) and base (NaOH) etching technique are used to create hierarchical mordenite having different pore structure. The powder X-ray diffraction (P-XRD) technique was used to confirm the crystalline structure of the base modified and acid modified mordenite. Field emission-Scanning electron microscope (FE-SEM) was employed to confirm the structural morphology of the materials. The modified mordenite were further characterized by Inductive coupled plasma-optical emission spectrometry (ICP-OES), N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), acid base titration, to confirm the structural integrity, presence of active acidic sites, and other vital parameters. The structure was well conserved after the change, as evidenced by the characterization. The toluene alkylation with benzyl alcohol using hierarchical Mordenite and H-Mordenite produced mono-benzylated toluene. Comparison between acid treated, base treated and H-Mordenite was done. All samples were catalytically active as proved by the catalytic result in the alkylation reaction. The results show that the base alteration dramatically enhances the mesoporous surface area of H-Mordenite. Furthermore, the acid treated Mordenite had the highest benzyl alcohol conversion (75%), but the base modified Mordenite had benzyl alcohol conversion of 73% with the highest mono-benzylated toluene selectivity (61%). The process was further optimised by varying the reaction temperature, duration, and catalyst quantity. Gas Chromatography (GC) was used to evaluate the reaction products and gas chromatography-mass spectrometry (GC-MS) was used to confirm them. Introduction of mesoporosity in the microporous Mordenite was found to have significant effect on their catalytic activity.

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Desilication of ZSM-5 and ZSM-12 Zeolites with Different Crystal Sizes: Effect on Acidity and Mesoporous Initiation

Cited by 22 publications

References 36 publications

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

Preparation of hierarchical H-[B]-ZSM-5 zeolites by a desilication method as a highly selective catalyst for conversion of methanol to propylene

Liquid-phase Alkylation of Toluene by Benzyl Alcohol over Micro-mesoporous Hierarchical Mordenite Zeolite

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