The Influence of Acid Treatment on the Sorption Properties of Latvian Clays

n-Hexane and carbon tetrachloride vapour sorption isotherms at 20°C are reported for two series (A and U) of Latvian clays. Samples of the A series were prepared from triassic montmorillonite clays by sulphuric or hydrochloric acid treatment at 100°C. Samples of the U series were prepared from quaternary hydromica clays in the same way. It was found that the vapour sorption isotherms exhibit a reproducible closed hysteresis loop at P/P0 = 0.3–0.99. For samples of series A, both the shape and the location of the hysteresis loop change as the acid concentrations increase. The BET specific surface area of both series samples increases at first and then decreases as the concentration of acid increases. Kelvin pore radii distribution curves have been calculated. It was found that the pore radius increases when the concentration of acid increases. The total pore volume of the samples was estimated as the amount of adsorbed vapour at P/P0=0.99. The pore volume at first increases and then decreases when the concentration of acid increases.

Determination of structure parameters of platinum hydrogenation catalysts and their supports

Six catalysts containing 5 and 6.1 wt. % Pt were prepared by impregnation of activated carbon (Atlas AET 300) with H2PtCl6 from aqueous solutions and subsequent calcination and reduction with hydrogen at 100, 200, and 300 °C. The specific surface area was determined for the catalysts, saturated supports and the untreated support. The adsorption isotherms of n-pentane at 0 °C were measured for the support, saturated support and catalyst (100 °C), and the experimental data were correlated by the BET, Langmuir, and Dubinin equations; the pore radii distribution was also calculated for them. The activities of the catalysts were evaluated by measuring the initial reaction rates of hydrogenation of 1-octene and nitrobenzene.