Theoretical Investigation on Syngas Production by Catalytic Partial Oxidation of Methane in a Reverse-Flow Microchannel Monolithic Reactor

Abstract

In this work, the use of a reverse-flow microchannel monolithic reactor is theoretically studied for improving the performance of syngas production by catalytic partial oxidation of methane over an Rh/Al2O3 catalyst. This helps to make a better judgment about the possibility of syngas production using this type of small-scale reactor. Imposing reverse-flow operation on catalytic microchannels creates eminent features that enable overcoming some drawbacks of technologies based on partial oxidation and increasing the reaction performance. A one-dimensional heterogeneous unsteady-state model is employed to model the reactor behavior. The full GRI 3.0 mechanism is employed to model the gas-phase reactions, and a detailed Langmuir-Hinshelwood surface mechanism is considered for catalytic reactions. The effects of feed preheat temperature, feed CH4/O2 ratio, reaction pressure, and flow switching time on methane conversion and syngas quality and yield are studied. The performance of the reverse-flow operation was also compared with the unidirectional one. The simulation results agree with the literature-reported experimental data, and the model can predict the reactor behavior well. The results show that the reverse-flow operation can significantly improve the syngas production yield and reduce the minimum preheat temperature required to light off the reactor. The maximum syngas production yield of ∼75% and H2/CO ratio of ∼2.7 are achieved at a feed CH4/O2 ratio of ∼1.6 after the cyclic steady state is established. The reverse-flow operation increases the methane conversion and syngas yield by at least 8% and 76%, respectively, compared with the unidirectional one. © 2023 American Chemical Society