Liquid phase oxidation of n-octane to C8 oxygenates over modified Fe-MOF-5 catalysts

• Metal Organic Framework materials containing Fe and Fe/Zn were prepared.
• n-Octane was selectively oxidized with H2O2 to C8 oxygenates only.
• Up to 20% selectivity to primary (C-1) functionalized oxygenates was obtained.
• The catalysts are stable, can be recycled and no leaching of metals was observed.

The Metal Organic Framework materials Fe4-MOF-5, Fe2–Zn2-MOF-5 and Fe0.9–Zn3.1-MOF-5 were prepared. The XRD results showed the expected pattern of MOF-5 with a very sharp peak at a 2θ value below 10° which indicate that the material is highly crystalline. The SEM and TEM images showed that the catalysts are cubic in shape. The synthesised Fe4-MOF-5, Fe2–Zn2-MOF-5 and Fe0.9–Zn3.1-MOF-5 were tested in the oxidation of n-octane using H2O2 as an oxidant in acetonitrile as solvent. Conversions of 10.5, 4.2 and 3.6% were obtained for Fe4-MOF-5, Fe2–Zn2-MOF-5 and Fe0.9–Zn3.1-MOF-5 respectively. It was observed that primary carbon activation increased with decreasing Fe content, as C-1 selectivities of 9.5, 12.9 and 19.8% were achieved for Fe4-MOF-5, Fe2–Zn2-MOF-5 and Fe0.9–Zn3.1-MOF-5 respectively. Only C8 oxygenate products were observed, which include 1-octanol, 2-octanol, 3-octanol, 4-octanol, octanal, 2-octanone, 3-octanone, 4-octanone and octanoic acid. Furthermore, these catalysts were tested in the oxidation of cyclohexane using H2O2 in acetonitrile. Selectivities of 48.3% for cyclohexanol, 47.1% for cyclohexanone and 4.6% for hydroperoxycyclohexane were recorded at a conversion of 40% using Fe4-MOF-5 as a catalyst.

Activation of n-octane and cyclohexane over modified Fe-MOF-5 using hydrogen peroxide as an oxidant.Figure optionsDownload as PowerPoint slide