Conglomerated system of Ag nanoparticles decorated Al2O3 supported cobalt and copper complexes with enhanced catalytic activity for oxidation reactions

Abstract In this study, our aim is to increase the effectiveness of heterogeneous catalysts by reducing its drawback. For this purpose we have developed a new method to synthesize heterogeneous catalyst by dispersion of Silver nanoparticles onto Alumina supported cobalt and copper Schiff base complexes ( AgNPs-Al 2 O 3 @ML ).Initially Schiff base and its corresponding Co (III) complex, ( CoL ) and Cu (II) complex, (CuL)(L = Schiff base) were synthesized. Both the complexes were immobilized on Al 2 O 3 to generate Al 2 O 3 @CoL ( HT1 ) and Al 2 O 3 @CuL ( HT2 ). Finally, Silver was dispersed onto both the heterogeneous complexes to generate our desired heterogeneous catalyst Ag NPs-Al 2 O 3 @CoL ( AgHT1 ) and Ag NPs-Al 2 O 3 @CuL ( AgHT2 ).A hike in BET surface area from HT1 to AgHT1 highlighted the fruitfulness of decoration of Ag NPs onto HT1 . FESEM studies of AgHT1 and AgHT2 reveal the formation of pyramidal type silver nanoparticle onto HT1 and HT2 . The catalytic ability of CoL , CuL (homogeneous catalyst), HT1 , HT2 and AgHT1 , AgHT2 (heterogeneous catalyst) were investigated by enrolling it on oxidation of alcohols, alkanes and epoxidation of alkenes using H 2 O 2 as oxidant. Among the four heterogeneous catalysts AgHT1 showed highest activity. Finally a plausible mechanism has been put forward to elucidate the role of each substituent of the catalytic system. The heterogeneous catalysts HT1 , HT2 , AgHT1 and AgHT2 can be reused up to six times without any significant loss in its catalytic activity.