Valorization of Different Wastes and Their Use for the Design of Multifunctional Eco-catalysts

Abstract

The desire to protect the environment for future generations has led to the reutilization of all recoverable and recyclable wastes. Consequently, different residues from various sources were collected to make mixed compounds to be used as catalyst supports. Such wastes included sand and cement from the building industry, nonreturnable glass bottles, and used tires. The synthesized supports were impregnated with molybdophosphoric acid, a heteropolyacid with Keggin structure, and characterized by potentiometric titration, optical microscopy, SEM–EDS, and textural property analyses. The bifunctional properties of the new catalysts were evaluated in two relevant transformations in green conditions: (i) the selective oxidation of sulfides to sulfoxides using a green oxidant such as tertbutyl hydroperoxide, and (ii) the multicomponent synthesis of 3,4-dihydropyrimidinones (Biginelli reaction, catalyzed in acid media).