Oxidative Coupling of Methane over Hybrid Membrane/Catalyst Active Centers: Chemical Requirements for Prolonged Lifetime

Solid oxide membrane/catalyst hybrid systems have been proposed as a promising platform for selective oxidative coupling of methane to form higher value C2+ products. In these hybrid systems, the membrane controls the local chemical potential of reacting oxygen atoms while the catalyst allows for selective reaction of these oxygen atoms with methane to form the desired C2 products. One critical challenge with these systems is that due to relatively low local O2/CH4 ratios, they can promote carbon-induced catalyst deactivation. Herein, we demonstrate that a BaCe0.8Gd0.2O3-δ based membrane/catalyst system can achieve excellent carbon resistance at low O2/CH4 ratios, and high and stable selectivity (over 80%) to C2+ products (ethane, ethylene, propane, and propylene). Our analysis of the system suggests that its high carbon resistance is due to its relatively high oxygen storage/release capacity which suppresses carbon deposition in the system.