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

Journal Article · Tue Dec 31 04:00:00 EST 1996 · Preprints of Papers, American Chemical Society, Division of Fuel Chemistry

OSTI ID:433094

Song, Chunshan; Lai, Wei-Chuan; Schmitz, A D ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States); and others

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{degrees}C, 240-340{degrees}C, and 340-500{degrees}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, consuming 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 VAX, 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.

• OSTI ID: 433094
• Report Number(s): CONF-960376--
• Journal Information: Preprints of Papers, American Chemical Society, Division of Fuel Chemistry, Journal Name: Preprints of Papers, American Chemical Society, Division of Fuel Chemistry Journal Issue: 1 Vol. 41; ISSN 0569-3772; ISSN ACFPAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALORIMETRY
CATALYSTS
CHEMICAL PROPERTIES
DESORPTION
HYDROTHERMAL SYNTHESIS
MORDENITE
PORE STRUCTURE
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
THERMAL GRAVIMETRIC ANALYSIS
ZEOLITES