Pulse reactions of methane, ethane and ethylene over Li-, La- and Sm-promoted MgO catalysts in the presence and absence of free oxygen

Pulse reaction of methane in the presence and absence of free (or gaseous) oxygen and that of ethane and ethylene in the absence of free oxygen over Li−MgO, La−MgO and Sm−MgO (Li or La or Sm/Mg ratio=0.1) have been investigated for elucidating the role of lattice and free oxygen in oxidative coupling of methane (OCM) over these catalysts. No significant role is played by the lattice oxygen from these catalysts in the OCM process. The presence of free oxygen is essential for all these catalysts to be active and selective in OCM process. However, lattice oxygen plays some role in ethane conversion but a very significant role in ethylene conversion over these catalysts.