PNNL

Abstract

NOx abatement from H2 internal combustion engines (H2-ICEs) is challenging due to high H2O content and unburnt H2 in the exhuast. This study examines Cu-SSZ-13 SCR catalysts, focusing on the effects of high H2O and H2 levels on its activity and stability. High H2O content typical of H2-ICE exhaust hinders low-temperature SCR activity by impeding Cu migration and oxidation half cycle efficacy. H2 slip decreases high-temperature SCR activity by reducing active Cu sites to the inactive CuI state. Combined, high H2O and H2 slip reduce SCR performance across all temperatures, making it less effective than in diesel applications. Additionally, aging under high H2O and H2 contents induce a severe deterioration of Cu-SSZ-13 via CuOx formation and dealumination, further degrading catalyst performance. This suggests Cu-SSZ-13 may not be suitable for H2-ICE aftertreatment, especially given the ongoing development of H2-ICE itself. Parallel efforts in H2-ICE and catalyst development are essential to accelerate H2-ICE deployment.