The synthesis of Na-Fe-Silicalite-1(80), Na-Fe-Silicalite-1(128), Na-Fe-ZSM-5(78) and Na-Fe-ZSM-5(126) was conducted using the isomorphic substitution method. These catalysts were further modified by the process of silanisation to yield Na-Fe-Silicalite-1(80:Sil), Na-Fe-Silicalite-1(128:Sil), Na-Fe-ZSM-5(78:Sil), and Na-Fe-ZSM-5(126:Sil) (The numbers in brackets represent the Si/Fe molar ratio and Sil represents silanization). The XRD analyses show that only the ZSM-5 phase was present in all the catalysts. These catalysts were tested in the oxidation of n-octane in MeCN using H2O2 as an oxidant. It was found that the selectivity to terminal products increased with increasing the volume of MeCN. Thus, e.g. terminal C8 selectivities could be improved from 17 to 28% using the Na-Fe-Silicalite-1(80) catalyst by increasing the volume of solvent. Furthermore, the Na-Fe-Silicalite-1(80), Na-Fe-Silicalite-1(80:Sil), Na-Fe-Silicalite-1(128) and Na-Fe-Silicalite-1(128:Sil) show terminal selectivities of 28.1, 14.3, 17.6 and 12.3% respectively. In contrast Na-Fe-ZSM-5(78), Na-Fe-ZSM-5(126), Na-Fe-ZSM-5(78:Sil), and Na-Fe-ZSM-5(126:Sil) show terminal selectivities of 24.5, 25.7, 21.3 and 27.3% respectively. Results also showed that the Na-Fe-ZSM-5 catalyst has better selectivity to terminal products than Na-Fe-Silicalite-1.
N-Octane Oxidation Iron Zeolite Silanisation Octanol Octanone Octanal
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We thank c*change (Grant No. PAR06.2), the NRF, THRIP (Grant No. TP1208035643), Clariant and the University of KwaZulu-Natal for support.