Determination of the Tolman length in the improved Derjaguin-Broekhoff-de Boer theory for capillary condensation of ethanol in mesoporous thin films by ellipsometric porosimetry

Ethanol adsorption–desorption isotherms on well-organized mesoporous silica and titania films with hexagonal pores structure were studied by ellipsometric porosimetry. The mesopore volume was calculated from the change of the effective refractive index at the end points of the isotherm. An improved Derjaguin–Broekhoff–de Boer (IDBdB) model for cylindrical pores is proposed for the determination of the pore size. In this model, the disjoining pressure isotherms were obtained by measuring the thickness of the ethanol film on a non-porous film with the same chemical composition. This approach eliminates uncertainties related to the application of the statistical film thickness determined via t-plots in previous versions of the DBdB model. The deviation in the surface tension of ethanol in the mesopores from that of a flat interface was described by the Tolman parameter in the Gibbs–Tolman–Koening–Buff equation. A positive value of the Tolman parameter of 0.2 nm was found from the fitting of the desorption branch of the isotherms to the experimental data obtained by Low Angle X-ray Diffraction (LA-XRD) and Transmission Electron Microscopy (TEM) measurements in the range of pore diameters between 2.1 and 8.3 nm

Liquid-phase hydrogenation of citral on Au/TiO2 and Pt-Sn/TiO2 thin films in capillary microreactors

Abstract only

Highly dispersed supported Pt-Sn/TiO2 catalysts derived from mixed metal cluster precursors for selective hydrogenation of [alpha],[beta]-unsaturated aldehydes

Abstract onl

Development of highly selective Pt-Sn catalysts on mesoporous titania for hydrogenation of citral to unsaturated alcohols

Novel bimetallic catalysts on mesoporous titania containing Pt-Sn nanoparticles derived from a carbonyl complex for selective hydrogenation of citral were developed. The influence of nature of Pt Sn precursor, its concentration, solvent used, Pt Sn solution/TiO2 ratio, adsorption duration, type of catalyst activation treatment on the content, structural and electronic properties of supported metals were studied. Under optimal synthesis conditions high dispersion of Pt3 Sn particles (mean size 1.5 nm) and narrow size distribution (1-3 nm) were achieved. The correlation between synthesis conditions and physicochemical properties of Pt-Sn catalysts has been established. In citral hydrogenation, the bimetallic catalysts showed a TOF of 0.2-3.3 mm-’ and a high selectivity to unsaturated aldehydes (80-90%) even at high conversions