Electropox: BP’s Novel Oxidation Technology

Abstract

Solid oxide electrochemical cells and oxygen transporting membranes have been used to conduct oxygen separation and partial oxidations simultaneously in a single reactor. As the substrate hydrocarbon never comes into contact with free oxygen, enhanced selectivity and unusual reactivity are to be expected. Important mechanistic insights and the development of Electropox, a new process for converting methane to syngas, have resulted from this work.

Studies of methane oxidation using solid oxide fuel cells show that high selectivities to C₂+ can be obtained by appropriate choice of electrocatalyst. In all cases selectivity decreases with increasing conversion, just as it does in the heterogeneously catalyzed reaction. A consecutive reaction scheme is proposed to account for the limit of the methane coupling yield, and co-feed experiments using CH₄/C₂H₄ mixtures support the mechanism. Operation of the cells at higher temperature results in a process integrating oxygen separation and syngas production into a single step, which we call Electropox.

Improvements in cell design and engineering have paralleled the Electropox process development. Advanced cell concepts have evolved that incorporate both electronic and ionic conducting functionalities into a single membrane. Oxygen transport rates have been demonstrated with these materials that may permit their use as oxygen separating membranes in chemical reactors.