Properties of the surface layer and catalytic activity of Ta2O5 with Pt or Pd additives in the oxidation of hydrogen

Activity and selectivity in hydrogen sulfide oxidation by oxygen on a Fe2O3/α-Al2O3 catalyst was studied at 200°C and atmospheric pressure. Reaction products were sulfur and sulfur dioxide. Two factors influencing catalytic activity were studied: support porous structure and the type of Fe2O3 precursor. The porous structure influenced substantially catalytic activity; mesopores were more active than macropores. The catalysts prepared from Fe(NO3)3 and iron(III) acetylacetonate exhibited comparable activity, the lower activity was found for the catalyst prepared from Fe2(SO4)3. The selectivity to sulfur formation was higher on catalysts containing greater amount of macropores and the value of it changed in the interval 0-85% depending on the type of catalyst.

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The effect of the content of sulphonic acid groups of an ion exchanger upon its catalytic activity

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19790502 ◽

1979 ◽

Vol 44 (2) ◽

pp. 502-507 ◽

Cited By ~ 4

Author(s):

Karel Setínek

Keyword(s):

Surface Layer ◽

Catalytic Activity ◽

Liquid Phase ◽

Alkali Metal ◽

Reaction Rates ◽

Sulphonic Acid ◽

Ion Exchanger ◽

Alkali Metal Ions ◽

Initial Reaction ◽

Different Thickness

Measurements of the initial reaction rates of the gas and liquid phase reesterification of ethyl acetate by 1-propanol catalyzed by an acid ion exchanger showed that the gradual neutralization of the acid groups by alkali metal ions in aqueous medium decreases uniformly their concentration within the whole mass of the catalyst, which reflects in the gradual decrease in the catalytic activity. On varying the content of sulphonic acid groups by sulphonation of the starting copolymer to a different degree, the ion exchangers possessing fully sulphonated surface layer of different thickness are formed which exhibit the same catalytic activity. The decrease in the activity has been observed only after the sulphonation degree was less than 50 per cent.

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Surface Composition of Carburized Tungsten Trioxide and its Catalytic Activity

MRS Proceedings ◽

10.1557/proc-48-85 ◽

1985 ◽

Vol 48 ◽

Cited By ~ 4

Author(s):

Masatoshi Nakazawa ◽

H. Okamoto

Keyword(s):

Surface Layer ◽

Catalytic Activity ◽

Tungsten Carbide ◽

Photoelectron Spectroscopy ◽

Tungsten Trioxide ◽

Surface Composition ◽

Electronic Density ◽

X Ray ◽

Electro Oxidation ◽

The Relationship

AbtractThe surface composition and electronic structure of carburized tungsten trioxide are investigated using X-ray photoelectron spectroscopy (XPS). The relationship between the surface composition and the catdlytic activity for methanol electro-oxidation is clarified. The tungsten carbide concentration in the surface layer increases with the carburization time. The formation of tungsten carbide enhances the catalytic activity. On the other hand, the presence of free carbon or tungsten trioxide in the surface layer reduces the activity remarkably. It is also shown that, the higher the electronic density of states near the Fermi level, the higher the catalytic activity.

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