Observation of Brønsted acid sites of DY zeolite with deuterium NMR

Gluszak, T. J.; Chen, Daniel T.; Sharma, Seema; Dumesic, James A.; Root, Thatcher W.

doi:10.1016/0009-2614(92)86098-3

Cited by 26 publications

(12 citation statements)

References 18 publications

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“…The main conclusion of this work that the presence of copper improves silanol acidity in silica is consistent with the observations of improved Brønsted acidity in zeolites 84 and amorphous aluminosilicates in the presence of heteroatoms. 68 For example, Cre´peau et al found that acidic OH groups in amorphous aluminosilicate samples containing a silica/alumina mixed phase as well as in materials with separate alumina clusters and pure silica regions correspond to the silanol groups located in close proximity to an Al 3+ ion.…”

Section: Comparison With Literature Reportssupporting

confidence: 91%

DFT investigation of NH3 physisorption on CuSO4 impregnated SiO2

Ambati

Saiyed

Rankin

2012

Phys. Chem. Chem. Phys.

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In this quantum chemical investigation, NH(3) physisorption onto a model of copper sulfate impregnated silica is compared with pure silica and copper sulfate adsorbents. The physisorption process is modeled as direct binding of the NH(3) molecule to the adsorption site of the dry adsorbents and as displacement of a H(2)O molecule by NH(3) in the hydrated complexes. The surface of silica is represented by a hydroxyl group attached to a silsesquioxane cage, H(7)Si(8)O(12)(OH) and silica impregnated with CuSO(4) by the most stable configuration of the cluster containing a CuSO(4) ion pair placed adjacent to the silica cage. H(2)O is systematically added to the dehydrated adsorbents to investigate the role of water in NH(3) adsorption. Modeling hydrated environments of each type of adsorbent is focused on H(2)O molecules that directly coordinate with the active sites. The results indicate that the binding energy of adsorbing NH(3) onto the mixed adsorbent is greater than in pure silica. This enhanced binding in the mixed adsorbent is consistent with improved Brønsted acidity of the silanol in the presence of CuSO(4).

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Section: Comparison With Literature Reportssupporting

confidence: 91%

DFT investigation of NH3 physisorption on CuSO4 impregnated SiO2

Ambati

Saiyed

Rankin

2012

Phys. Chem. Chem. Phys.

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“…25 In fact, a distribution of all three types are present in the structure of zeolite with a preponderance of one type depending on localization in the framework. 41 It must be considered that if the zeolite presents a high site density, Lewis and Brønsted sites can be very close to each other, so if a strong Brønsted site is complexed by a large molecule like quinoline, the weaker neighboring acid site is no longer accessible to a second molecule. 32 Dealuminated zeolites can have their acid site density decreased by the presence of amorphous alumina and aluminosilicate debris.…”

Section: Cal-ad Resultsmentioning

confidence: 99%

Acidity measurements of zeolite Y by adsorption of several probes

Dias

Macedo

Dias

2003

Phys. Chem. Chem. Phys.

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“…Solid-state NMR has been used for the characterization of acidity in zeolites and other materials for decades [67][68][69][70]. Different nuclei can be used for the characterization of SiOHAl groups, i.e., 1 H, 17 O, 29 Si, 27 Al, as well as other nuclei connected with probe molecules.…”

Section: Experimental Methods Employed For the Acidity Studies Of Zeomentioning

confidence: 99%

Acid Properties of Hierarchical Zeolites Y

Gackowski

Dátka

2020

Molecules

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The article reviews different strategies towards obtaining mesoporous zeolites Y: desilication; surfactant templating and assembly of zeolite crystals. The impact of those methods on physicochemical properties is covered, with a special focus on the acidity of the samples measured with infrared (IR) spectroscopy. The methods of characterization of acidity are presented. Quaternary ammonium cations used for desilication lead to obtaining crystalline; mesoporous and highly acidic zeolites. Si-OH-Al groups of extremely high acidity can be produced by calcination in a humid atmosphere. When the conditions are optimized, post-synthetic surfactant templating allows crystalline mesoporous zeolite to be obtained with no loss of material. All mesoporous zeolites Y proved to be active catalysts in liquid phase isomerization, catalytic cracking, and other reactions.

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Observation of Brønsted acid sites of DY zeolite with deuterium NMR

Cited by 26 publications

References 18 publications

DFT investigation of NH3 physisorption on CuSO4 impregnated SiO2

DFT investigation of NH3 physisorption on CuSO4 impregnated SiO2

Acidity measurements of zeolite Y by adsorption of several probes

Acid Properties of Hierarchical Zeolites Y

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