Zoltán Hlavathy

Adsorption of C1–C3 alkanes and C2–C3 alkenes on Pt as studied by work function changes and Auger electron spectroscopy

The pressure and temperature dependence of the adsorption of methane, ethane, propane, ethene and propene on a Pt ribbon have been characterised by work function changes |Δφ| and the carbon to platinum ratio (C/Pt), determined from C/Pt AES peak intensity. C/Pt increases were accompanied by an increase of |Δφ| up to a certain value only. Carbon uptake was not followed by increase of |Δφ|, i.e. of surface coverage above this value, thereby indicating the formation of three-dimensional carbonaceous deposits. The calculated maximum coverages were substantially lower than 1, indicating the presence of constant number of non-covered platinum surface sites despite increasing amount of carbon uptake. The maximum surface coverages were nearly the same for methane, ethane and propane. With regard to the dipole moments of adspecies, formed at adsorption of ethane and propane these were equal and significantly higher than those of adspecies formed upon methane adsorption.

Adsorption of alkanes and alkenes on Pt as studied by work function changes

Adsorption of methane, ethane, propane, neopentane, ethene and propene has been studied on polycrystalline Pt between 323 and 573 K. The adlayer was stable in vacuum up to 473 K. The H2 partially removed the adlayer below 450 K and stabilized it above 500 K.

Interaction of hydrogen with C1 and C2 hydrocarbons adsorbed on Pt surface

Abstract The effect of hydrogen has been studied on hydrocarbons adsorbed on Pt ribbon. Parallel measurements were carried out of work function changes (WFC) and of the C/Pt peak to peak ratio in the Auger electron spectra. Hydrogen-induced desorption was observed and for adsorbed CH4 and C2H6 at low temperatures, addition of hydrogen to surface adspecies.

ADSORPTION OF METHANE AND ETHANE : 1. STUDIES OF WORK FUNCTION CHANGES OF PT FOIL. EFFECT OF PRESSURE

Pt work-function changes have been measured on adsorption of methane and ethane at different temperatures in the 10−5–10−2 mbar pressure range. Correlations were found between pressure of hydrocarbons and Pt work function changes.

Uptake of C6 cyclic hydrocarbons on Pt

Abstract Adsorption of benzene and cyclohexane was studied by Auger electron spectroscopy and work function change measurements on polycrystalline Pt, and the results were compared with earlier studies with C 1 –C 3 hydrocarbons. It was found that the adsorption of the cycles is not hindered, the adlayer hardly interacts with hydrogen, and that benzene and cyclohexane form similar adspecies.

Conversion of ethene and propene adsorbed on Pt foil

The conversion of ethene and propene has been studied in the process of adsorption on Pt foil and in adsorbed state. Mainly C−C bond cleavage and limited C−C bond formation was observed in 323–523 K temperature interval.