Platinum catalysts supported on graphitized carbon black—I: Characterization of the platinum by titrations and differential calorimetry

Abstract A graphitized carbon black and samples resulting from its oxidation in air at 798 K over different periods of time have been used as supports for platinum catalysts. Platinum dispersion and mean diameter of platinum particles have been determined by O 2 -H 2 , H 2 -O 2 and O 2 -CO titrations and by differential calorimetry of the O 2 -H 2 reaction. Comparison of titration results does not permit an unambiguous choice of Pt O or Pt CO ratios to be used in the titration stoichiometries. However, results from the calorimetric study suggest that the Pt O ratio should be taken as one. Dispersion increases with increasing burn-off of the support, the surface area of the support being the principal factor conditioning the platinum dispersion, although there is also a smaller contribution due to the increase in surface heterogeneity.