Expanded Reactor Engineering Calculations for the Oxidative Coupling of Methane

Abstract

The catalytic activation of CH4 by limited amounts of O2 produces a mixture of synthesis gas (CO, H2) and light hydrocarbons (C2Hx), the relative amounts of each depending on catalyst type and process conditions. Using an elementary reaction mechanism for the oxidative coupling of methane (OCM) on a La2O3/CeO2 catalyst derived from the literature, this study replaces the activating O2 with moist H2O2 vapor to reduce synthesis gas production while improving C2Hx yields and selectivities. As the H2O2 content of the activating oxidant rises, more of the CH4 conversion occurs in the gas phase instead of with the catalytic surface. In a packed bed reactor (PBR), the use of H2O2 allows the PBR “light-off” to occur using a lower feed temperature. In exchange for a small decline in CH4 conversion, C2Hx selectivity increases while synthesis gas production drops. In a continuous stirred tank reactor (CSTR), H2O2 improves C2Hx over synthesis gas across a wider range of feed temperatures than is possible with the PBR. This suggests the CSTR will likely reduce OCM preheating requirements.