Pt nanoparticles with different mean sizes supported on XC-72R were prepared by an improved impreganation-reduction method, using HCHO as a reducing reagent and ethylene glycol as a dispersing solvent of H₂PtCl₆ instead of isopropyl alcohol. The Pt/C catalysts were characterized by XRD, TEM and XPS. Highly-dispersed Pt/C catalysts could be prepared by the improved impreganation-reduction method easily, and the size of Pt particles could be controlled by changing the solution pH. TEM examinations show that the mean Pt particle size decreased from 3.3 to 1.8 nm with the increase of pH values from 1.6 to 11.3. The contents of Pt(0), Pt(II) and Pt(IV) of Pt/C catalysts, fabricated at pH 11.3, are 43.3%, 30.8% and 25.9%, respectively. Then polytetrafluoroethylene (PTFE) and Pt/C catalysts with different mean sizes of Pt particles were supported on foamed nickel (FN) to obtain hydrophobic Pt/C/FN catalysts. The catalytic activities of the hydrophobic catalysts were investigated for hydrogen-water liquid phase exchange reaction. The catalytic activity increased with the decrease of the mean size of Pt particles of Pt/C/FN catalysts.

Key words: hydrophobic catalyst, hydrogen-water liquid phase catalytic exchange reaction, hydrogen isotope separation, highly-dispersed Pt/C catalyst