Effect of Pd–TiO2 interaction on the enthalpy of hydrogen absorption

Abstract

The uptake of hydrogen (chemisorption and absorption) by palladium supported on titania has been measured volumetrically at various temperatures. On increasing the hydrogen pressure, a-phase palladium hydride absorbed hydrogen and transformed into p-phase. The transition pressure increased with the measuring temperature. The enthalpy of the transition was decreased by increasing the temperature for reduction pretreatment. These variations are attributed to electronic interactions between the metallic palladium and the reduced support (TiO,).

Thermodynamics of hydride formation and decomposition in supported sub-10nm Pd nanoparticles of different sizes

“…Specifically, each isotherm was approximated by three lines within the miscibility region, and the midpoint of the two intercepts was chosen as the plateau pressure for a given isotherm. Similar procedures have been employed by others previously [15,16,17].…”

The activity and stability of Pd/C catalysts in benzene hydrogenation

“…The exothermic enthalpy from exposing Pd/C to reaction gas at 298 K includes: H 2 chemisorption (15-24 kcal/mol [16,28,29]), H 2 absorption (ca. 10 kcal/mol [16,[28][29][30][31]), benzene adsorption (12-18 kcal/mol [5,32]) and reaction enthalpy (49 kcal/mol Bz). If the hydrogen is repeatedly stopped and flown during a benzene reaction test (i.e., using the bracketing procedure), the thermal fluctuation at the surface may be is significant.…”