Characterization of acidic properties of microporous and mesoporous zeolite catalysts using TGA and DSC

Chunshan Song, Wei Chuan Lai, Andrew D. Schmitz, Kondam Madhusudan Reddy

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied for characterizing the acidic properties of microporous and mesoporous zeolite catalysts through temperature-programmed desorption (TPD) of n-butylamine (n-BA) as a base probe molecule. A flow system was designed with heating and evacuation capability for preparing the n-BA adsorbed sample. In the TGA, n-BA desorption at different temperatures represents the interaction with surface acidic sites of different strength. The acid sites corresponding to base desorption at 100-240°C, 240-340°C, and 340-500°C, were classified as weak, intermediate, and strong acid sites, respectively. DSC indicates the endothermic nature of the differential thermogravimetric peaks (observed from TGA) in the above temperature regimes, confirming the TPD data. The microporous zeolites examined include three proton-form mordenites, three proton-form and metal-ion exchanged Y-zeolites, and four noble metal catalysts supported on mordenite and Y-zeolite. Four mesoporous zeolites were synthesized and examined by the same TPD method. Both the total acidity (mmol/g) and acid strength distribution depend on the zeolite type, Si/Al ratio, and metal loading. Ni and La ion-exchange decreased the strong acid sites. Pt and Pd loading on an HY decreased the strong acid sites but their loading on an H-mordenite had little effect on its strong acid sites. Mesoporous zeolites showed lower acidity and lower fraction of strong acid sites compared to HY and H-mordenites. However, the acidity of mesoporous zeolites strongly depends on the aluminum source compounds used in the hydrothermal synthesis of the zeolites.

Original languageEnglish (US)
Pages (from-to)71-76
Number of pages6
JournalACS Division of Fuel Chemistry, Preprints
Volume41
Issue number1
StatePublished - Dec 1 1996

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Gravimetric analysis
Zeolites
Differential scanning calorimetry
Catalysts
Acids
Temperature programmed desorption
Acidity
Desorption
Protons
Hydrothermal synthesis
Precious metals
Hot Temperature
Catalyst supports
Metal ions
Ion exchange
Aluminum
Heating
Temperature
Molecules
Metals

All Science Journal Classification (ASJC) codes

  • Energy(all)

Cite this

Song, Chunshan ; Lai, Wei Chuan ; Schmitz, Andrew D. ; Reddy, Kondam Madhusudan. / Characterization of acidic properties of microporous and mesoporous zeolite catalysts using TGA and DSC. In: ACS Division of Fuel Chemistry, Preprints. 1996 ; Vol. 41, No. 1. pp. 71-76.
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abstract = "Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied for characterizing the acidic properties of microporous and mesoporous zeolite catalysts through temperature-programmed desorption (TPD) of n-butylamine (n-BA) as a base probe molecule. A flow system was designed with heating and evacuation capability for preparing the n-BA adsorbed sample. In the TGA, n-BA desorption at different temperatures represents the interaction with surface acidic sites of different strength. The acid sites corresponding to base desorption at 100-240°C, 240-340°C, and 340-500°C, were classified as weak, intermediate, and strong acid sites, respectively. DSC indicates the endothermic nature of the differential thermogravimetric peaks (observed from TGA) in the above temperature regimes, confirming the TPD data. The microporous zeolites examined include three proton-form mordenites, three proton-form and metal-ion exchanged Y-zeolites, and four noble metal catalysts supported on mordenite and Y-zeolite. Four mesoporous zeolites were synthesized and examined by the same TPD method. Both the total acidity (mmol/g) and acid strength distribution depend on the zeolite type, Si/Al ratio, and metal loading. Ni and La ion-exchange decreased the strong acid sites. Pt and Pd loading on an HY decreased the strong acid sites but their loading on an H-mordenite had little effect on its strong acid sites. Mesoporous zeolites showed lower acidity and lower fraction of strong acid sites compared to HY and H-mordenites. However, the acidity of mesoporous zeolites strongly depends on the aluminum source compounds used in the hydrothermal synthesis of the zeolites.",
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Characterization of acidic properties of microporous and mesoporous zeolite catalysts using TGA and DSC. / Song, Chunshan; Lai, Wei Chuan; Schmitz, Andrew D.; Reddy, Kondam Madhusudan.

In: ACS Division of Fuel Chemistry, Preprints, Vol. 41, No. 1, 01.12.1996, p. 71-76.

Research output: Contribution to journalArticle

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