The sorption of hydrogen on palladium in a flow system

Abstract

0.3–3% Pd/Al 2O 3 catalysts were prepared using the incipient wetness method. The dispersion of these catalysts was measured by various chemisorption techniques and agreement between the techniques was reasonable. The dispersion of freshly prepared catalysts decreased with the palladium content and the measured dispersions were used to calibrate the peaks of hydrogen sorption on palladium using a temperature controlled flow system. Hydrogen was found to be reversibly sorbed (includinn adsorption and absorption) and desorbed from palladium under 76 Torr hydrogen pressure between room temperature and 400°C. The peak ratio of the hydrogen absorbed into the bulk to the hydrogen adsorbed on the surface depends on the dispersion of palladium particles. This ratio may be used to estimate the dispersion of freshly prepared palladium catalysts with dispersions in the range of 10% to 80%.