Numerical investigation on the discharge formation in micrometer pores in structured catalyst irradiated by a helium atmospheric pressure plasma jet

Abstract

Non-thermal plasma catalysis is a promising way to achieve high efficiency in applications such as energy conversion and chemical engineering. Although synergistic effect between plasma and catalysts has been preliminarily considered as an underlying mechanism of this type of catalysis, the formation of discharges in small-size catalyst pores, which is possible a crucial factor in plasma-activated catalysis, is still not well understood. In this paper, investigations on the interactions between a helium atmospheric pressure plasma jet (APPJ) and catalysts with micrometer-size pores of different shapes and sizes are conducted with a 2D fluid model. Simulation results show that the existence of pores makes subtle difference to the APPJ by changing equivalent capacitance, indicating the potential to achieve moderate and stable APPJ-catalysts interactions. Trace of air impurity in helium can promote the discharges in catalyst pores, and thus allow discharges forming in smaller pores. In the case when a catalyst channel is too small for direct APPJ penetration, we propose a method by producing a prior discharge in a relatively large cavity to supply seed electron to ignite discharges inside the channel. The effects of channel and cavity sizes are discussed from perspectives of discharge behavior and plasma-surface interactions. This work will contribute to the preparation of structured catalysts to potentially achieve higher efficient plasma catalysis, and better understanding the physical processes in plasma-surface interactions inside micrometer pores.