Determination of Platinum in Pt/SiO₂-Al₂O₃ Catalyst

Spectrophotometry was applied to the determination of platinum in Pt/SiO2-Al2O3 catalyst. The sample was dissolved in hydrofluoric acid,hydrochloric acid,phosphoric acid and hydrogen peroxide. In an acidic solution of 1.2 mol·L-1 HCl,anionic chloroplatinic ion (PtCl2-6) was reduced by SnCl2 solution to form the yellow colored chloroplatious acid (H2PtCl4),the absorption maxima of which was found at the wavelength of 403 nm,with its molar absorptivity of 4.59×104L·mol-1·cm-1. Beer′s law was obeyed in the range of 0-10 mg per 100 mL of solution. The proposed method was used in analyzing 4 samples of the catalyst with 9 determinations for each sample,values of RSD′s found were less than 4%,and of recovery were in the range 101% to 106%. Two of the samples were checked by analyzing with XRFS,consistent results were obtained.