Multi-scale modeling and simulation of low-pressure methane bi-reforming using structured catalytic reactors

Abstract

Methane bi-reforming has gained interest recently for its potential of converting CH4 and CO2 into chemicals while avoiding catalyst deactivation by coke formation. Recycling CO2 produced can be considered, but introduces constraints on the allowable pressure drop over the reactor. The latter is particularly the case in low-pressure processes, such as those encountered in the steel industry. The paper reports on a multi-scale modeling approach for a structured catalytic reactor that offers lower pressure drop than classical pellets while improving heat transfer. The use of a thin catalytic coating furthermore improves the catalyst effectiveness. The coupled CFD-reaction model accounts for the details of the reaction mechanism and kinetics, intra-catalyst transport and the details of the flow pattern. Radiative heat transfer and thermal conduction in the reactor tube walls and in the reactor internals coated with catalyst are also taken into account. Several scale-bridging strategies have to be introduced and combined to allow a computationally tractable solution. This requires a variety of detailed experimental data, an aspect that is also discussed. The coupled CFD-reaction model was first validated using data from a bi-reforming pilot plant and then used to evaluate the performance of a structured reactor under typical commercial process conditions and to study optimization of the reactor design and potential increase in capacity.