ANALYSIS OF OXIDATIVE COUPLING OF METHANE IN DENSE OXIDE MEMBRANE REACTORS

Oxidative coupling of methane (OCM) in dense oxide membrane reactors is analyzed using a model based on equations that describe OCM kinetics on membrane surface, oxygen permeation through the membrane, and mass transfer and reactions in membrane CSTR or PFR. The membrane consists of an oxygen ionic conducting oxide layer with one surface serving as catalyst for OCM. The kinetic equations considering the involvement of lattice oxygen in the catalytic reactions are derived and extended, with the same parameters, to describe OCM kinetics on the oxide layer operated in the membrane mode. Calculation results show a possibility of achieving much higher C-2 yields (> 70%) for OCM in the dense oxide membrane reactors than in conventional packed-bed reactors. Using an impervious but highly oxygen permeable ceramic membrane with an OCM catalytically active surface is essential to achieving the high C-2 yields for OCM in a membrane reactor. The yield is also very sensitive to characteristics of membrane, reaction conditions and reactor size. A high C-2 yield can be achieved only under the conditions that the oxygen permeation flux, methane flow rate and intrinsic reaction rate match each other. Parametric analysis is presented to examine the effects of several important parameters on the performance of OCM in membrane CSTR and PFR.