Probing Low-Temperature OCM Performance over a Dual-Domain Catalyst Bed

The Mn-Na₂WO₄/SiO₂ catalyst is regarded as the most promising catalyst for the oxidative coupling of methane (OCM). Despite its remarkable performance, the Mn-Na₂WO₄/SiO₂ catalyst requires a high reaction temperature (>750 °C) to show significant activity, a temperature regime that simultaneously causes quick deactivation. In the current work, we show that the benefits of this catalyst can be leveraged even at lower reaction temperatures by a using a stacked catalyst bed, which includes also a small amount of 5% La₂O₃/MgO on-top- of the Mn-Na₂WO₄/SiO₂ catalyst. The simple stacking of the two catalysts provides >7-fold higher activity and ~1.4-fold higher C₂ yield at 705 °C compared to Mn-Na₂WO₄/SiO₂ and La₂O₃/MgO, respectively. We specifically show that the enhanced OCM performance is associated with synergistic interactions between the two catalyst domains and study their origin.