Selective hydrogenation of detrimental 4-nitrophenol to desired 4-aminophenol over potent PtCo intermetallic nanoparticles entrapped within the pores of Cr-BDC MOFs

Engineering of economical and stabilized precious metal based catalysts are crucial in recent ages to achieve the desirable catalytic performance as they tend to destabilize easily. Herein, Cr-BDC MOF was prepared that provides high surface area and pore volumes to evenly distribute, host, and stabilize the Pt and Co intermetallic nanoparticles (IMNs). Among these, the PtCo/Cr-BDC catalyst showed superior selective hydrogenation activity for 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) as an exemplary reaction. A number of characterization techniques were carried out to study the influence of the Cr-BDC support and Co metal on the surface and bulk structural properties of active Pt metal species. The Cr-BDC support imparts uniform distributions while the Co metal species influenced the catalytic activity. The maximum conversion (99.3 %) of 4-NP to 4-AP was observed with PtCo/Cr-BDC in 2 min at a reaction rate constant (k) of 1.27 min⁻¹ at room temperature, which is superior than Pt/Cr-BDC (0.64 min⁻¹) and Co/Cr-BDC (0.14 min⁻¹). The superior hydrogenation activity was credited to the addition of electropositive Co species to Pt/Cr-BDC catalyst that synergistically interacts with active Pt species within the pores of Cr-BDC MOFs and making PtCo IMNs system. As a result of this synergistic interaction, new additional interfacial electrophilic and nucleophilic metallic sites are generated within the pores of MOFs, which enormously encourage the selective hydrogenation of lethal 4-NP to valued 4-AP. Besides, the PtCo/Cr-BDC catalysts revealed remarkable durability up to several repeated rounds, validating its real-world applicability.