Stable and Surface-active Co Nanoparticles Formed from Cation (x) Promoted Au/x-Co₃O₄ (x=Cs) as Selective Catalyst for [2+2+1] Cyclization Reactions

Surface-active and highly stable cobalt nanoparticles generated from alkali ion-promoted gold catalyst for catalyzed carbonylative [2+2+1] cyclization reaction, is described. The gold nanoparticle‘s (AuNPs) role was assumed to dissociate the CO and H₂ into atomic species on the catalyst surface by spillover, which in-situ reduces the robust mesoporous cobalt oxide to metallic cobalt (Co³⁺→Co²⁺→Co), as the active catalytic species that catalyzed the reaction; thereby providing up to 93 % yield of cyclopentenone adducts. Prior to this, catalyst pre-treatment with H₂ gas (130 °C, 3 h, 20 atm) was performed to reduce the catalyst. It appeared that the low reducibility temperature and increased surface basicity ascribed to the presence of alkali ion-promoters in the catalyst revealed a strong correlation with the catalyst activity, for the intra- and intermolecular reactions under milder reaction conditions. Thus, a sustainable, highly reusable, and environmentally friendly green catalyst for the carbonylation reaction, such as Pauson-Khand, was developed.