Partial oxidations of CH4 and C2H6 at low pressure over H- and Na-ZSM-5 catalysts Original Research Article

The partial oxidation of CH4 was carried out over the H-, Na-, and Na excess-ZSM-5(SiO2/Al2O3 = 283) (MFI) catalysts. The selectivity to CH3OH was high for Na-ZSM-5 while that to HCHO was high for H-ZSM-5. Little or no selectivity to CH3OH and HCHO was observed over Na excess-ZSM-5. H2 formation occurred over H- and Na-ZSM-5 catalysts during the oxidation of CH4, its rate depending on the O2 concentration and the acidic sites. With the oxidation of C2H6 over H-ZSM-5, the oxidative dehydrogenation of C2H6 to C2H4 as well as the cracking reaction to CH4 and H2 took place. The lattice oxygen of H-ZSM-5(283) exhibited higher 18O exchange activity with 18O2 than over the Na-ZSM-5 catalyst. Commercial silicas exhibited very low 18O exchange activities. The high selectivities to CH3OH and HCHO and a scheme of the oxidation of CH4 are presented.