Shape selective oxidation by a microporous platinum-polyoxometalate
Shape selective catalytic behaviour of a platinum-promoted polyoxometalate, 0.5 wt% Pt−Cs2.1H0 9PW12O40, has been studied for complete oxidation of methane 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 N2 porosimetries demonstrated that 0.5 wt% Pt−Cs2 1H0 9PW12O40 possesses unimodal distribution of pores in ultramicropore region. External surface area was estimated to be less than 3% that of the total surface area (61 m2 g−1) of the catalyst. Owing to the restricted pores, this exhibited efficient shape selectivity; methane (molecular size; 0.38 nm) was readily oxidized, while the oxidations of the larger molecule such as benzene (0.59 nm) were greatly suppressed. These results indicate that 0.5 wt% Pt−Cs2 1H0 9PW12O40 is a promising microporous catalyst.
KeywordsZeolite Selective Oxidation Isobutane Pore Size Distribution Curve Effective Pore Diameter
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