Direct oxidation of benzene to phenol over hierarchical ZSM-5 zeolites prepared by sequential post synthesis modification

Shahid, Ameen; Lopez‐Orozco, Sofia; Marthala, V. R. Reddy; Hartmann, Martin; Schwieger, Wilhelm

doi:10.1016/j.micromeso.2016.09.012

Cited by 30 publications

(14 citation statements)

References 44 publications

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“…loop indicates that the material has a structure of piece agglomeration. P-MgO after adsorption of Congo red has a H3-type hysteresis loop [30].…”

Section: Nitrogen Adsorption-desorptionmentioning

confidence: 99%

Combustion synthesis of porous MgO and its adsorption properties

2019

Int J Ind Chem

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Porous magnesium oxide was synthesized by a combustion method, with Mg(NO 3) 2 , ethylene glycol and deionized water as reactants, and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and nitrogen sorption/desorption. The results showed that the as-prepared porous magnesium oxide has the multi-scale porous size with a large BET surface area of 203.8 m 2 g −1. Magnesium oxides synthesized with other reactants have rod-shaped and granular morphologies, and their BET surface areas are 17.6 and 3.4 m 2 g −1 , respectively. Compared to the magnesium oxide with the low specific surface area, porous magnesium oxide exhibited higher adsorption efficiency with a maximum adsorption capacity of approximately 1088 mg g −1 in removing Congo red. The as-synthesized porous magnesium oxide could be used as an efficient adsorption material in Congo red removal from the wastewater.

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“…loop indicates that the material has a structure of piece agglomeration. P-MgO after adsorption of Congo red has a H3-type hysteresis loop [30].…”

Section: Nitrogen Adsorption-desorptionmentioning

confidence: 99%

Combustion synthesis of porous MgO and its adsorption properties

2019

Int J Ind Chem

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“…In Figure 2 the wide angle diffractogram could be seen for both parent microporous NaY and hierarchical MY. As can be observed the characteristic peaks at 2ϴ 6.1°, 11.8°, 15.5°, 20.2° and 23.4° related to a NaY zeolite has maintained after modification to hierarchical MY but ( ) q e : the adsorbed amount at equilibrium (mg g -1 ) C e : the adsorbate equilibrium concentration (mgL -1 ) a T : Toth isotherm constant (L/mg) t: Toth isotherm constant K T : Toth isotherm constant (mg/g) because of partially destructions of parent microporous NaY crystals, which are in charge of the zeolite XRD patterns, and formation of mesoporosity, the intensities of hierarchical MY peaks have been diminished [7,19].…”

Section: Characterization Of Adsorbentsmentioning

confidence: 99%

Improved removal of methylene blue on modified hierarchical zeolite Y: Achieved by a “destructive-constructive” method

Ramezani

Azizi

Cravotto

2019

Green Processing and Synthesis

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In this study removal of methylene blue (MB) from an aqueous solution by zeolite (NaY) and related modified hierarchical zeolite (MY) has been investigated. The NaY zeolite with a low ratio of Si/Al was synthesized from silica extracted rice husk ash. It was transformed to hierarchical zeolite (MY) by a “destructive-constructive” modification method using tetramethyl ammonium hydroxide (TMAOH) and a cationic surfactant (Cetyltrime-thylammonium bromide, CTAB) as a templating agent. Various characterization method like FT-IR, XRF, XRD, BET, TGA, SEM and BJH confirmed the construction of parent zeolite and also successfulness of the modification process. EDX showed a negligible change of Si/Al ratio during modification which is favorite in adsorption of cationic MB dye. In order to study the interaction between the surface of adsorbent and adsorbate, six common isotherms were used. By Langmuir isotherm, it is clarified that, the maximum adsorption capacity (qm) had improvement from 15.2 mg g-1 to 133.1 mg g-1 for NaY and MY, respectively. The kinetic studies showed that the adsorption obeys the Pseudo-second order model for both NaY and MY zeolites. Also, the usage frequency of the MY was investigated. Results showed that there was not any noticeable change in performance of adsorption after four circles.

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“…a novel method to nely tune the acidity of H-beta zeolites. It has been found that dealumination of beta zeolites by steaming, 17 leaching with mineral acids such as HCl, 18 and treatments with chemicals such as ammonium hexauorosilicate, 19 and organic acids 20,21 are effective for this purpose. Among these approaches, acid leaching is considered to be the most feasible route from the point of view of environmental protection and industrial application, but the negative effects of dealumination by acid leaching are structural changes in zeolite crystals and uncontrollable loss of framework aluminum atoms that decreases active sites.…”

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confidence: 99%

Carboxylic acids to butyl esters over dealuminated–realuminated beta zeolites for removing organic acids from bio-oils

Liu

et al. 2017

RSC Adv.

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This article describes a novel method to dealuminate and realuminate H-beta zeolites as catalysts for removing organic acids from bio-oils via their esterification reactions with alcohols. Modified H-beta zeolites were prepared by leaching with solutions of oxalic acid, DL-malic acid, and DL-tartaric acid that have different numbers of hydroxyl groups. The results showed that, while all three organic acids can dealuminate the parent H-beta zeolite, with Al(VI) a atoms and Al(IV) c ones being preferentially removed, they show quite different realumination abilities, with tartaric acid with two hydroxyl groups having the highest realumination ability. The concomitance of dealumination and realumination and their dependence on the hydroxyl group numbers of the organic acids provide the possibility of finely tuning the Al and acidity distributions of the resulting zeolites. Among the three acid treated H-beta zeolites, the one obtained from malic acid leaching exhibited the best performance in catalyzing the esterification reaction between acetic acid and sec-butyl alcohol, attributed to its suitable quantity and density of medium and strong Brönsted acid sites and enhanced aluminum gradient. The catalytic results obtained in a fixed-bed microreactor revealed that the malic acid leached H-beta exhibited dramatically enhanced catalytic performance compared to the commercial ion-exchange resin Amberlyst® 15, demonstrating great potential for industrial application.

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Direct oxidation of benzene to phenol over hierarchical ZSM-5 zeolites prepared by sequential post synthesis modification

Cited by 30 publications

References 44 publications

Combustion synthesis of porous MgO and its adsorption properties

Combustion synthesis of porous MgO and its adsorption properties

Improved removal of methylene blue on modified hierarchical zeolite Y: Achieved by a “destructive-constructive” method

Carboxylic acids to butyl esters over dealuminated–realuminated beta zeolites for removing organic acids from bio-oils

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