Significant catalytic activity recovery of deactivated industrial Du-Pont VPO catalysts by surface deposition of small amounts of oxide phosphorius-vanadium phase

Important efforts have been made to protect VPO catalysts against deactivation using metal promoters and optimizing the regeneration conditions. Deactivation mechanisms may include crystallization of amorphous phase, accumulation of carbonaceous species on the surface or transformation of V4+ into V3+ sites. We present results obtained using a deactivated DuPont’s VPO catalysts which has been significantly reactivated by a new and original method, namely by deposition of a small amount of a particular VPO phase on its surface. Results show that deactivation of Du Pont’s VPO catalysts is probably due to the generation during the reaction of a very high amount of V+5 from V+4 species. Reactivated catalysts allow to: i) reestablish the adequate V+5 / V+4 ratio ii) recover about 50% of the loss in AM production, iii) improve selectivity and conversion.