Ferenc Berger

Preparation and structural properties of Pd nanoparticles in layered silicate

Abstract Pd nanocrystals in the 5–15 nm ranges were prepared on pillared clay minerals (PILCs) as supports by immobilizing Pd nanoparticles in the interlamellar space of montmorillonite and saponite by pillaring with aluminium hydroxide cations. Pd nanoparticles were generated via reduction by ethanol of Pd acetate present in the adsorption layer at room temperature. The structure of Pd-PILC samples was characterized by XRD and N 2 gas sorption measurements. The Pd/H interaction was characterized by H 2 sorption isotherms, which revealed extensive sorption hysteresis depending on particle size. This effect calls attention to the potential use of Pd-PILC adsorbents for storage of gaseous H 2 . Microcalorimetry was carried out to determine H 2 gas sorption enthalpy isotherms, which also exhibited a sorption hysteresis. By combining the data, H/Pd interactions are also expressed as molar sorption enthalpies. It is concluded that, due to differences in surface accessibility for hydrogen, H/Pd interactions are determined by the joint effect of the external to total atomic ratio of Pd nanoparticles and the microporosity of the support pillared clays.

Adsorption of propene in zeolites possessing sites of different adsorption energies

Abstract Adsorption of propene in NaA, CoNaA and CoMgNaA was found to be non-dissociative and reversible. The strength of interaction of propene with the exchange cations decreased in the order: Co2+ > Mg2+ > Na+. The Henrys constants and the isosteric heat of adsorption at low coverages were determined. The Fowler equation was found applicable for the description of adsorption.

Variable thickness of the liquid sorption layers on solid surfaces

Abstract Calculations of the adsorption capacity and the thickness of the adsorption layer are of primary importance for studies of the adsorption of binary mixtures. Earlier methods were applicable to the determination of real adsorption capacity only in the case of monolayers and/or layers of constant thickness, independent even of mixture composition. In the case of the adsorption isotherms of binary mixtures of non-electrolytes these conditions are often not fulfilled, and neither the Schay–Nagy extrapolation method nor reciprocal isotherm representations can be used for the determination of adsorption capacity on the basis of adsorption isotherms. Here we present a method of calculation suitable for the computation of surface composition and adsorption layer thickness in the whole composition range. Thus, instead of a single value of adsorption capacity, the system is characterized by the layer thickness isotherm given as a function of the composition of the bulk phase.

Binary solvent mixture adsorption as a characterisation tool to determine the hydrophilic/hydrophobic properties of multiwall carbon nanotubes

A simple method is offered to quantitatively characterise the hydrophobic/hydrophilic properties of carbon nanotubes by measuring binary solvent mixture adsorption.