The effects of surface doping of vanadyl pyrophosphate with K and co-feeding NH3 or SO2 on the selective oxidn. of butane are reported. The active sites of consecutive maleic anhydride oxidn. to COx can be specifically poisoned by the addn. of SO2. The presence of ammonia or doping with very limited amts. of K inhibit the active sites of butane activation and oxygen insertion, but have less effect on the transformation of 1-butene to butadiene and furan. The lowering of the selectivity to maleic anhydride parallels the redn. in the surface Broensted acidity. It is sugggested that Broensted sites are responsible for the formation or stabilization of strongly held surface adsorbates and that this interaction is the key step in the mechanism of maleic anhydride synthesis. V5+ sites are principally responsible for the consecutive oxidn. of maleic anhydride. Their interaction with SO2 forms a probably stable V4+ sulfate with inhibition of the rate of combustion of maleic anhydride. [on SciFinder(R)]

Nature of the active sites of vanadyl pyrophosphate in the selective oxidation of butane: evidence from doping experiments

CENTI, Gabriele;
1989-01-01

Abstract

The effects of surface doping of vanadyl pyrophosphate with K and co-feeding NH3 or SO2 on the selective oxidn. of butane are reported. The active sites of consecutive maleic anhydride oxidn. to COx can be specifically poisoned by the addn. of SO2. The presence of ammonia or doping with very limited amts. of K inhibit the active sites of butane activation and oxygen insertion, but have less effect on the transformation of 1-butene to butadiene and furan. The lowering of the selectivity to maleic anhydride parallels the redn. in the surface Broensted acidity. It is sugggested that Broensted sites are responsible for the formation or stabilization of strongly held surface adsorbates and that this interaction is the key step in the mechanism of maleic anhydride synthesis. V5+ sites are principally responsible for the consecutive oxidn. of maleic anhydride. Their interaction with SO2 forms a probably stable V4+ sulfate with inhibition of the rate of combustion of maleic anhydride. [on SciFinder(R)]
1989
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/1907344
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