Asymmetric support-side deposition strategy for high-permeance tubular CePO4/SiC catalytic membranes enabling synergistic PM and NOx removal

Abstract

Catalytic membranes are promising multifunctional materials for integrated pollutant control. However, conventional impregnation-based catalyst loading strategies often allow catalytic particles to infiltrate the separation layer, resulting in severe pore blockage and reduced permeance. Herein, we develop a rapid and low-cost asymmetric support-side deposition approach to fabricate tubular CePO₄/SiC–S catalytic membranes, which effectively prevents catalyst penetration into the separation layer, minimizes pore blockage, and thereby enhances the permeance. The results indicate that CePO₄ catalysts are mainly anchored within the pores of the SiC support, rather than in the separation-layer pores, thereby preserving efficient gas transport pathways and avoiding direct contact between particulate matter (PM) and catalytic sites. Compared with conventional vacuum impregnation, the proposed method achieves comparable ammonia selective catalytic reduction (NH₃-SCR) activity while reducing permeance loss from 35.44% to only 20.09%. The membrane demonstrated exceptional stability during a 240 h continuous operation at 350 °C, maintaining a dust rejection rate of >99.99% and NO conversion >90%. Notably, dust cake formation was found to further enhance catalytic efficiency, particularly under low filtration velocities (0.5 m min⁻¹). Computational fluid dynamics (CFD) simulations revealed that moderate cake deposition promotes uniform flow distribution and extends residence time, thereby improving catalyst utilization. This work provides a scalable fabrication strategy for high-permeance catalytic membranes, offering a practical pathway for synergistic control of multiple pollutants at high temperatures.