Preparation of Pt-Re/Al2O3 catalysts by surface redox reactions .1. Influence of operating variables on Re deposit in the presence of hydrochloric acid

The preparation of bimetallic Pt-Re/Al2O3 catalysts was investigated by surface redox reaction between hydrogen adsorbed on a 'parent' platinum/alumina catalyst and rhenium ions. Rhenium can be deposited under an inert atmosphere ('recharge' method), but the rhenium deposit is limited by the amount of hydrogen irreversibly adsorbed on surface platinum. When the reaction is carried out under hydrogen atmosphere ('catalytic reduction'), this technique allows to deposit large amounts of rhenium. The partial pressure of hydrogen, the temperature of the reaction, the concentration and the nature of the rhenium salt and the dispersion of the 'parent' monometallic platinum catalyst strongly influence the kinetic and the extent of rhenium deposition by catalytic reduction.