Cetyl alcohol mediated fabrication of forest of Ag/Mn3O4 nanowhiskers catalyst for the selective oxidation of styrene with molecular oxygen

Abstract

Cetyl alcohol-mediated water-based preparation of nanocrystalline Ag/Mn₃O₄ catalyst has been reported in a one-pot preparation method. This catalyst has been characterized by XRD, XPS, SEM, TEM, STEM-mapping, FTIR, Raman and ICP-AES. Electron microscopy displayed the formation of whisker-like one-dimensional structure. TEM-images revealed the formation of ultrasmall Ag (with average size 5 nm), anchored on hausmannite-type tetragonal Mn₃O₄ spinel (with diameter 30–40 nm). It was found that the catalyst can effectively oxidize styrene with molecular O₂ as oxidant. The effect of different reaction parameters like reaction temperature, pressure of oxygen gas, reaction time etc. have been investigated in detail. A styrene conversion of 67% with a styrene-oxide selectivity of 100% accomplished over this catalyst. Nano-whiskers like unique morphology of the catalyst and the thorough dispersion of Ag nanoparticles on Mn₃O₄ spinel support are the detrimental factors of the reactivity of the catalyst. The catalyst did not show any leaching up to five reuses, showing its true heterogeneity nature.