Shape selective oxidation by a microporous platinum-polyoxometalate

Shape selective catalytic behaviour of a platinum-promoted polyoxometalate, 0.5 wt% PtCs2.1H0.9PW12O40, has been studied for complete oxidation of met hane and benzene. The pore size of this catalyst determined by adsorptions of n-butane and isobutane was close to the molecular size of n-butane (0.43 nm). Ar and N-2 porosimetries demonstrated that 0.5 wt% Pt-Cs2.1H0.9PW12O4 0 possesses unimodal distribution of pores in ultramicropore region. Extern al surface area was estimated to be less than 3% that of the total surface area (61 m(2) g(-1)) of the catalyst. Owing to the restricted pores, this e xhibited efficient shape selectivity; methane (molecular size; 0.38 nm) was readily oxidized, while the: oxidations of the larger molecule such as ben zene (0.59 nm) were greatly suppressed. These results indicate that 0.5 wt% Pt-Cs2.1H0.9PW12O40 is a promising microporous catalyst.