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