Abstract:
A multilayer supported oxidative coupling of methane (OCM) catalyst composition (support, first single oxide layer, one or more mixed oxide layers, optional second single oxide layer) characterized by formula AZEDO/support; A is alkaline earth metal; Z is first rare earth element; E is second rare earth element; D is redox agent/third rare earth element; the first, second, third rare earth element are not the same; a=1.0; b=0.1-10.0; c=0.1-10.0; d=0-10.0; x balances oxidation states; first single oxide layer (ZO, b1=0.1-10.0; x1 balances oxidation states) contacts support and one or more mixed oxide layers; one or more mixed oxide layers (AZEDO, a2=1.0; b2=0.1-10.0; c2=0.1-10.0; d2=0-10.0; x2 balances oxidation states; AZEDOand AZEDOare different) contacts first single oxide layer and optionally second single oxide layer, and second single oxide layer (AO), when present, contacts one or more mixed oxide layers and optionally first single oxide layer.