Study on the laws of methanol reforming coupled with flow, heat and mass transfer processes with variable catalyst distribution in microchannels

Reactions in microchannel reforming reactors are related to flow and heat/mass transfer, which have an important impact on hydrogen production efficiency. In this paper, a strategy to improve methanol conversion and reduce catalyst cost is obtained by using forced unsteady-state operation, i.e., adopting a catalyst variable-activity arrangement, and by means of experiments and numerical simulations to analyze the mechanism of the enhanced reaction in this way from the perspective of coupled flow and heat-mass transfer. The results demonstrate that the two-section arrangement schemes can increase the Le number and enhance the thermal diffusion. And the "low-high" scheme can make the wall temperature more uniform. In the three-stage arrangement scheme, the methanol conversion rate of "low-high-low" can reach 89.6%. From the second stage onward, the effect of heat mass transfer on the chemical reaction is more significant. Secondly, the interrupted catalyst arrangement effectively improves the heat and mass transfer in the reactor. The methanol conversion was significantly improved by dividing the reactor into four sections, and the best arrangement was "low-none-high-low", which could achieve 91.2% conversion. The catalyst arrangement of "low-none-low-none" is the most effective solution in terms of hydrogen production performance and catalyst cost.