The role of Pt-loading, thermal treatment and exposure to air on the acid-base behavior of a Pt/Carbon black catalyst

The acid-base properties of a series of Pt/carbon black catalysts varying in Pt loadings and in nitrogen activation temperature (110°C-900°C) were investigated using a potentiometric titration technique. The amounts of acidic and basic surface functional groups were found to differ significantly, denoting a paramount influence on them of the catalyst precursor (H2PtCl6) and of the activation temperature levels. The exposure to air also causes variations in surface properties, mainly through the effect of the relative humidity.