New Method for the Temperature- Programmed Desorption (TPD) of Ammonia Experiment for Characterization of Zeolite Acidity: A Review

Niwa, Miki; Katada, Naonobu

doi:10.1002/tcr.201300009

Cited by 172 publications

(97 citation statements)

References 157 publications

(142 reference statements)

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“…The acidic property was analyzed by means of ammonia IRMS‐TPD method 42. Figure 3 also shows the amount of the Brønsted and Lewis acid sites as overlapped on the catalytic activity.…”

Section: Resultsmentioning

confidence: 99%

“…The acidic property was analyzed by a method of ammonia IRMS‐TPD in conditions described elsewhere 42. Morphology of the catalyst was analyzed with a TEM (HITACHI H800 B) in accelerating voltage 200 kV.…”

Section: Methodsmentioning

confidence: 99%

“…X‐ray absorption near edge spectroscopy (XANES) and extended X‐ray absorption fine structure (EXAFS) were utilized to characterize the oxidation state and structure of active species in atomic scale. Ammonia infrared mass spectrometry‐temperature programed desorption (IRMS‐TPD), which was recently developed by our group,42 was also applied for the quantitative analysis of Brønsted and Lewis acid sites, showing the quantities of ion exchange sites uncovered and covered by the transition metal species. The analysis of Lewis acidity is also related directly to the activity, because it has been known that Lewis acid strength affects the activity in reactions of methylation reagents 43…”

Section: Introductionmentioning

confidence: 99%

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Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite

et al. 2018

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Cobalt‐loaded MFI zeolite showed distinct activity for direct methylation of benzene with methane into toluene. High activity was found at around 0.6 of Co/Al molar ratio. Incorporation of carbon from methane into the methyl group of toluene was confirmed with isotope tracer experiments and mass spectroscopy. Ammonia infrared‐mass spectroscopy temperature‐programmed desorption, transmission electron microscopy, X‐ray absorption near edge spectroscopy and extended X‐ray absorption fine structure indicated that Lewis acidic divalent (+II of oxidation state) Co species mono‐atomically dispersed on the ion exchange site of MFI zeolite was the active species.

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“…The acidic property was analyzed by means of ammonia IRMS‐TPD method 42. Figure 3 also shows the amount of the Brønsted and Lewis acid sites as overlapped on the catalytic activity.…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite

et al. 2018

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“…The relations found will be a function, among others, of the desorption equilibrium constant, which is itself dependent on the adsorption enthalpy. The TPD has been widely used to characterize solid catalyst and new developments have been made on the methodology [63,64]. This technique in combination with ammonia has been used with HZSM-5 zeolite to discuss on its acidity [31, 65 -68].…”

Section: Temperature-programmed Desorption (Tpd) Of Ammoniamentioning

confidence: 99%

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Corma

Cuquerella

Miguel

2015

Journal of Catalysis

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An extended dual kinetic model allows to fit the n-heptane cracking results working in a wide range of reaction conditions. The duality of the model is provided by the contribution of monomolecular and bimolecular cracking mechanisms. It takes into account the role played by the olefins formed on the global cracking or added within the feed. Furthermore by means of this model and the kinetic parameters obtained when cracking n-heptane on ZSM-5, it has been observed that, while some characterization techniques show a homogeneous zeolite surface from the point of view of the active sites, rigorous kinetic experiments point to the possibility that the reactant sees a heterogeneous surface with, at least, two group of cracking active sites. Those differentiated active sites give different cracking rates and different activation energies for the process and, in the case of ZSM-5, could be assimilated to sites pointing to the 10R channels and sites pointing into the crossing of the 10R channels, mainly due to differences in acid site location and confinement effects.3

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“…NH 3 can adsorb strongly on Brønsted acid sites and weakly on top of each other on these sites via hydrogen bonds or on Lewis sites (RodriguezGonzalez et al, 2008;Giodanino et al, 2014). Both acidic sides can be determined by temperature-programmed desorption (TPD) of NH 3 , but a direct differentiation between Lewis and Brønsted sites is still not possible (Niwa and Katada, 2013). Therefore, the ability to measure dielectric properties under reaction conditions during NH 3 storage, and to correlate them with the catalytic behavior of the materials in situ, offers new opportunities to analyze and identify acidic sites and to optimize the catalyst material in general.…”

Section: Introductionmentioning

confidence: 99%

Ammonia storage studies on H-ZSM-5 zeolites by microwave cavity perturbation: correlation of dielectric properties with ammonia storage

Dietrich

Rauch

Simon

et al. 2015

J. Sens. Sens. Syst.

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Abstract.To meet today's emission standards, the ammonia-based selective catalytic reduction (SCR) has become the major NO x control strategy for light and heavy diesel engines. Before NO x reduction can proceed, adsorption of ammonia on the acidic sites of the catalyst is necessary. For improvements in efficiency and control of the exhaust gas aftertreatment, a better understanding of the ammonia storage on the acidic sites of zeolite-based SCR catalysts is needed. Thereby, the correlation of dielectric properties of the catalyst material itself with the ammonia storage is a promising approach. Recently, a laboratory setup using microwave cavity perturbation to measure the dielectric properties of catalyst material has been described. This study shows the first experimental data on zeolite-based SCR materials in their H-form. The SCR powder samples are monitored by microwave cavity perturbation while storing and depleting ammonia, both with and without admixed NO x at different temperatures. Its complex dielectric permittivity is found to correlate closely with the stored mass of ammonia. The influence of the temperature and the Si / Al ratio of the zeolite to the ammonia storage behavior are also examined. These measurements disclose different temperature dependencies and differing sensitivities to ammonia storage for both real and imaginary parts of the complex permittivity. The apparent constant sensitivity of the real part can be related to the polarity of the adsorbed ammonia molecules, whereas the imaginary part depends on the Si / Al ratio and is related to the conductivity mechanisms of the zeolite material by proton hopping. It provides information about the zeolite structure and the number of (and the distance between) acidic storage sites, in addition to the stored ammonia mass.

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New Method for the Temperature- Programmed Desorption (TPD) of Ammonia Experiment for Characterization of Zeolite Acidity: A Review

Cited by 172 publications

References 157 publications

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Ammonia storage studies on H-ZSM-5 zeolites by microwave cavity perturbation: correlation of dielectric properties with ammonia storage

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