Bifurcation analysis of oxidative coupling of methane in monolith, gauze or wire-mesh reactors

Abstract

We use a multi-scale multi-mode reduced order model for coupled homogeneous-catalytic reaction systems to present a comprehensive bifurcation (ignition-extinction) analysis of the oxidative coupling of methane (OCM) in monolith, gauze or wire-mesh type reactors. We determine the impact of methane to oxygen ratio in the feed, space time, channel hydraulic radius (or gas phase to catalyst volume ratio), washcoat diffusional limitations, operating pressure and substrate thermal conductivity on the ignition and extinction behavior of the system as a function of the feed temperature. The computations show that for typical operating conditions, the methane conversion and C2 product selectivity are non-monotonic on the ignited branch and there exists an optimum point of operation away from the extinction point. The predicted methane, oxygen conversions and C2 selectivity are compared to reported experimental results in the literature. We also present the various species and temperature profiles along the length of the reactor and examine how these profiles are impacted by the substrate conductivity, space time and heat loss. The results obtained for monolith, gauze or wire-mesh reactors are compared to those in packed-bed reactors and suggestions are provided for scale-up and optimization of these reactors for carrying out OCM as well as other catalytic partial oxidations.