Plasma streamer propagation in structured catalysts

Plasma catalysis is gaining increasing interest for various environmental applications. Catalytic material can be inserted in different shapes in the plasma, e.g., as pellets, (coated) beads, but also as honeycomb monolith and 3DFD structures, also called 'structured catalysts', which have high mass and heat transfer properties. In this work, we examine the streamer discharge propagation and the interaction between plasma and catalysts, inside the channels of such structured catalysts, by means of a two-dimensional particle-in-cell/Monte Carlo collision model. Our results reveal that plasma streamers behave differently in various structured catalysts. In case of a honeycomb structure, the streamers are limited to only one channel, with low or high plasma density when the channels are parallel or perpendicular to the electrodes, respectively. In contrast, in case of a 3DFD structure, the streamers can distribute to different channels, causing discharge enhancement due to surface charging on the dielectric walls of the structured catalyst, and especially giving rise to a broader plasma distribution. The latter should be beneficial for plasma catalysis applications, as it allows a larger catalyst surface area to be exposed to the plasma.