Integrated autothermal oxidative coupling and steam reforming of methane. Part 2: Development of a packed bed membrane reactor with a dual function catalyst

Abstract

A numerical feasibility study was performed on the integral performance of dual function catalyst particles in a packed bed reactor equipped with a porous membrane for distributive feeding of oxygen. The exothermic oxidative coupling and the endothermic steam reforming of methane (for simultaneous production of ethylene and synthesis gas) are integrated at the level of a porous catalyst particle with distributed activity, where the presence of the intraparticle heat-sink strongly reduces the total reaction heat and the temperature gradients in the reactor, eliminating the need for expensive conventional cooling of the reactor.Numerical simulations, with reaction kinetics taken from the literature, revealed that with distributive oxygen feeding via membranes indeed the local oxygen concentration in the packed bed membrane reactor can be kept low, which combined with a high Thiele modulus for oxidative coupling makes dual function catalysis possible. Using a reforming core diameter of approximately 15–40μm, the steam reforming and oxidative coupling reaction rates could be effectively tuned to achieve autothermal operation, while the methane conversion was enhanced from 34 to 48% at optimum C2 production rates. In addition, it was shown that the temperature profiles in the reactor can be strongly reduced by employing the dual function catalyst and that the use of axial oxygen membrane flux profiles enables the use of a single particle configuration to approach autothermal operation in the entire reactor.