Influences of M–Sn intermetallics (M = Ni, Cu) prepared by mechanical alloying on phenol hydroxylation

Abstract

This work discusses the effect of the crystal structure of Ni–Sn and Cu–Sn intermetallic catalysts on phenol hydroxylation. All catalysts were prepared via the mechanical alloying (MA) technique which is a green process for catalyst preparation. The results showed that the prepared catalysts consisted of monoclinic (Ni₃Sn₄ and Cu₆Sn₅) and hexagonal (Ni₃Sn and Cu₆Sn₅(HT)) crystal structures. The catalytic activity of all synthesized catalysts for phenol hydroxylation demonstrated that both Ni₃Sn₄ and Ni₃Sn exhibited better catalytic activity than Cu₆Sn₅ and Cu₆Sn₅(HT), and Ni₃Sn, having a hexagonal crystal structure, showed the best catalytic activity (>97% conversion) at 363 K, 3 h, 1 : 4 phenol : H₂O₂, and 50 mg of catalyst content, giving CAT (60.28% yield) and HQ (36.82% yield) with no over-oxidation of CAT and HQ as time elapsed.