A calorimetric and statistical mechanics study of ammonia adsorption in zeolite NaY

Boddenberg, B.; Rakhmatkariev, G. U.; Wozniak, Aneta; Hufnagel, Stefan

doi:10.1039/b312429k

Cited by 10 publications

(7 citation statements)

References 22 publications

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“…The results obtained for the heats of adsorption (ΔH ads ) of water are in good agreement with reported values [25][26][27][28][29][30], which are around ~80 kJ/mol for FAU zeolites (52-96 Al). On the other hand, the model of ammonia leads to a ΔH ads of around ~60 kJ/mol, while reported experimental ΔH ads values for NaY (Al/Si = 2.43) are around ~75 kJ/mol [31,32]. It is clear that the model of ammonia underestimates the experimental data, however, this study aims to analyze the effect of aluminum substitution on the heat of adsorption.…”

Section: Resultsmentioning

confidence: 89%

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Zhakisheva

Gutiérrez‐Sevillano²,

Calero³

2023

Separation and Purification Technology

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Section: Resultsmentioning

confidence: 89%

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Zhakisheva

Gutiérrez‐Sevillano²,

Calero³

2023

Separation and Purification Technology

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“…For instance, for n-pentane adsorbed in NaX zeolite, such contribution is 3.7 kJ/mol, being 1 order of magnitude less than the van der Waals component. 2 A great number of examples show the effectiveness of the adsorption calorimetric method with Tian-Calvet calorimeters for the investigation of the crystallochemistry and adsorption thermodynamics on the pore adsorbents-zeolites [for instance, refs [3][4][5][6][7][8][9][10]. This method proved to be very successful for studying the energetics of the adsorption processes on clay mineral muscovite 11 and also on the nonporous surface of microcrystalline rutile.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Normal Pentane on the Surface of Rutile. Experimental Results and Simulations

2007

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Adsorption isotherms and differential heats of normal pentane adsorption on microcrystalline rutile were measured at 303 K. The heat of adsorption of n-pentane on rutile at zero occupancy is 64 kJ/mol. The differential heats have three descending segments, corresponding to the adsorption of n-pentane on three types of surfaces. At low coverage (first segment), the adsorption is restricted to the rows A of the (110) faces along the 5-fold coordinatively unsaturated (cus) Ti(4+) ions with differential heat showing a linear decrease with increasing occupancy. The second segment is attributed to bonding with atoms of the rows along the remaining faces exposed, (101) and (100). The third segment is related to a multilayer adsorption. The mean molar adsorption entropy of n-pentane is ca. -25 J/mol K less than the entropy of the bulk liquid, thus revealing a hindered state of motion of the n-pentane molecules on the surface of rutile. Simulations of the adsorption of n-pentane on the three most abundant crystallographic faces of rutile were also performed. The adsorption isotherm obtained from the combination of each face's isotherm weighted by the respective abundance was found to be in a good agreement with the experimental data. A structural characterization of n-pentane near the surface was also conducted, and it was found that the substrate, especially for the (110) face, strongly perturbs the distribution of n-pentane conformations, compared to those found for the gas phase. Adsorbed molecules are predominantly oriented with their long axes and their backbone zigzag planes parallel to the surface and are also characterized by fewer gauche conformations than observed in the bulk phase.

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“…Similar considerations are valid not only for supported metals but also for solid acid catalysts, as an enormous amount of calorimetric data exists on heats of adsorption on such microporous materials as zeolites. In particular, the adsorption of ammonia in zeolites has been extensively studied over many years. , Due to its small size and rather strong base character, ammonia is a preferred molecule to probe the number, type, and strength of acid sites in catalysts. In addition, in zeolite science, ammonia adsorption techniques have been widely used to study, inter alia, molecule/cation interactions, cation distributions, and energetic heterogeneity.…”

Section: Calorimetrymentioning

confidence: 99%

“…In addition, in zeolite science, ammonia adsorption techniques have been widely used to study, inter alia, molecule/cation interactions, cation distributions, and energetic heterogeneity. Supporting Information Figure S5 displays differential heats of adsorption of ammonia over the two zeolites NaY and NaY(NaBr), showing clearly that there is a continuous decrease of the heat of adsorption from 80 to ∼40−45 kJ/mol as adsorption progresses.…”

Section: Calorimetrymentioning

confidence: 99%

On Surface Heterogeneity and Catalytic Kinetics

Murzin

2005

Ind. Eng. Chem. Res.

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The effect of surface heterogeneity on catalysis and chemisorption is discussed. Available recent data on calorimetry, as well as on adsorption isotherms and reaction kinetics, are carefully reviewed. Despite the fact that the current catalytic engineering practice is very much limited to Langmuir−Hinshelwood kinetics based on concepts of ideal surfaces, there is a number of cases when such an approach is not sufficient enough for the modeling of the kinetics of heterogeneous catalytic reactions.

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A calorimetric and statistical mechanics study of ammonia adsorption in zeolite NaY

Cited by 10 publications

References 22 publications

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Adsorption of Normal Pentane on the Surface of Rutile. Experimental Results and Simulations

On Surface Heterogeneity and Catalytic Kinetics

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