Stopped-flow desorption analysis of the nature of strongly adsorbed species during n-butane oxidation in a flow reactor

The presence and the evolution as a function of time of strongly adsorbed species during butane oxidn. in a flow reactor was studied by stopped-flow desorption expts. and by thermogravimetric and Fourier-transform IR analyses on a (VO)2P2O7 catalyst highly active-selective in the conversion of butane to maleic anhydride. In particular, the presence of an adsorbed species was found which desorbs as crotonaldehyde only at temps. around 100 K higher than the reaction temp. (573 K). The parallel increase in the amt. of this species formed with the change in catalytic behavior (a decrease in the rate of butane depletion with a parallel increase in the rate of maleic anhydride formation) suggests that due to the reduced turnover no., the formation of strongly adsorbed species causes catalyst deactivation by site blocking, but at the same time allows controlled reactivity of the surface which prevents the consecutive oxidn. of maleic anhydride to carbon oxides. [on SciFinder(R)]