State of portholes responsible for spillover of hydrogen in Pt/MoO3

Pt which has been prepared in a dispersed form upon molybdena and subject to low temperature reduction is surprisingly active in alkane hydrogenolysis and in part this may be enhanced by the hydrogen-rich support (which having accepted spiltover hydrogen from Pt portholes (P.Meriaudeau and C.Naccache J. Catal. 157 (1995) 283) forms HxMoOy) in a non-transient or sacrificial manner. However, as the pre-reduction temperature was increased from 373 to 773K a substantial diminution in its hydrogenolysis activity towards propane was seen as x and y decreased and became irreversible, even after re-oxidation and mild reduction. These low temperature and high temperature interactions which produce such effects upon the Pt spillover 'portholes' may also be relevant to other MoO3-promoted metal catalysts.