Numerical simulation of particle/monolithic two-stage catalyst bed reactor for oxidative coupling of methane

•3D models were set up for OCM reactors using computational fluid dynamics method.•The effects of catalyst bed heights on reactor performance were investigated.•The simulated reactor performance matched well with the experimental.•The monolithic catalyst bed had a higher C2 selectivity than the particle bed did.•Effects of residence time and the CO2 blocking decided the reactor performance. Three-dimensional models were set up for the oxidative coupling of methane (OCM) two-stage packed bed reactors loaded with Na2WO4–Mn/SiO2 particle catalyst and Na3PO4–Mn/SiO2/cordierite monolithic catalyst using the computational fluid dynamics simulation. Firstly, the reactor with particle and monolithic catalyst bed heights of 10mm and 50mm was simulated. Secondly, the effects of particle and monolithic catalyst bed heights on reactor performance were investigated. The results showed that the simulation values matched well with the experimental values on the conversion of CH4 and the selectivity of products (C2H6, C2H4, CO, CO2) in the reactor outlet with an error range of ±10%. The monolithic catalyst bed had a higher C2 (C2H4 and C2H6) selectivity and less O2 consumed than the particle catalyst bed did. When the heights of particle and monolithic catalyst bed were 10mm and 50mm, respectively, the best values of C2 yield were 21.8% obtained due to the effects of residence time and the CO2 blocking in the oxidation reaction.