Hydrophobicity of Water-Tolerant Solid Acids Characterized by Adsorptions of Water and Benzene

Hydrophobicity of a “water-tolerant” solid acid, Cs2.5H0.5PW12O40, has been investigated by adsorptions of water and benzene. One water molecule was adsorbed irreversibly at 298 K per one proton of Cs2.5H0.5PW12O40 as well as H−ZSM-5 (Si/Al = 40), while H3PW12O40 formed a stable hexahydrate. From th...

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Bibliographic Details
Published in:Langmuir 2000-03, Vol.16 (5), p.2321-2325
Main Authors: Yamada, Takashi, Okuhara, Toshio
Format: Article
Language:English
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Summary:Hydrophobicity of a “water-tolerant” solid acid, Cs2.5H0.5PW12O40, has been investigated by adsorptions of water and benzene. One water molecule was adsorbed irreversibly at 298 K per one proton of Cs2.5H0.5PW12O40 as well as H−ZSM-5 (Si/Al = 40), while H3PW12O40 formed a stable hexahydrate. From the ratio of adsorption area of benzene to that of water, the hydrophobicity of the solid acid surface was estimated to be in the order H−ZSM-5 (Si/Al = 628) > SiO2 > Cs3PW12O40 > H−ZSM-5 (Si/Al = 40) ≃ Cs2.5H0.5PW12O40 > SiO2−Al2O3 > Al2O3, where the adsorption area is defined as the product of the adsorption amount and molecular cross-sectional area. It is thus concluded that the surface of Cs2.5H0.5PW12O40 has a hydrophobic nature close to that of H−ZSM-5 (Si/Al = 40). This hydrophobicity is responsible for the high catalytic activity of Cs2.5H0.5PW12O40 for hydrolysis of ester in excess water.
ISSN:0743-7463
1520-5827
DOI:10.1021/la9906020