Low temperature catalytic partial oxidation of ethane to oxygenates by Fe– and Cu–ZSM-5 in a continuous flow reactor

[Display omitted] •Ethane is oxidised to oxygenated products under continuous flow conditions.•Modified ZSM-5 catalysts are stable under reaction conditions.•Acetic acid yields of up to 16% are observed at the low temperature of 50°C.•Removal of non-reactive surface Fe species gives enhanced TOFs. The selective oxidation of lower alkanes, such as ethane, remains a major research challenge in catalysis. In this study Fe and Cu containing zeolites are investigated as catalysts for the production of C2 oxygenated products from ethane using H2O2 as an oxidant. We utilise a trickle bed reactor to effectively control the contact time between reactants and catalyst to minimise C–C scission and over oxidation to COx. Reaction conditions such as temperature, pressure and reactant concentration in combination with Fe and Cu content of the catalysts are investigated to optimise conversion and selectivity to C2 oxygenated products. A marked effect is observed upon increasing pressure between 1 and 30bar, as the oxygenate selectivity increases from 46% to 98%. Single pass conversion of ethane (22%) to acetic acid (73%, 16% yield) has been observed using a Fe/ZSM-5 catalyst under the optimum conditions. Catalysts are investigated for stability, and are observed to undergo no apparent deactivation under test conditions, despite low levels of Fe leaching. Through characterisation and assessment of leached Fe/ZSM-5 catalysts, we show that catalytic activity might be attributed to Fe species within the zeolite’s channels and that surface FexOy are spectator species. Finally, relatively high selectivity to ethene (38%, 1% yield) has been observed with Cu containing materials under these mild reaction conditions.