Oxidative coupling of methane in a ceramic membrane reactor: Uniform oxygen permeation pattern

This paper models the oxidative coupling of methane in a porous ceramic membrane reactor. The catalyst is packed in the tube side of a membrane reactor where the reaction takes place. Methane and oxygen are fed to the tube side and shell side of the membrane, respectively. The membrane controls the distribution of oxygen from the shell side to the tube side and, hence, improves the yield to C-2 hydrocarbon products. The side products such as carbon dioxide and water are suppressed because a low concentration of oxygen in the tube side is maintained. The performance of the membrane reactor is compared with a plug flow reactor where both reactants are fed together to the catalyst bed. It is found that the membrane reactor provides much higher selectivity to C-2 hydrocarbons than the plug flow reactor. Moreover, the membrane reactor is superior to the plug flow reactor in yield when the CH4/O-2 ratio and the oxygen feed side pressure are high. There is a minimum membrane thickness in which complete permeation oc curs for each operating condition. In addition, there is an optimum membrane thickness in which the yield is maximized.