The effect of support and promoters on the performance of Pt-based H2-SCR catalysts for NOx removal

H₂-combustion engines represent a promising alternative for achieving carbon neutrality. However, to efficiently remove the resulting NO x emissions, the current H₂-SCR technologies require a more in-depth understanding that will enable further catalyst improvements. In this context, this manuscript reports a systematic study on the effect of support and promoters on the H 2 -SCR performance of Pt-based catalysts. Parameters such as catalyst pre-treatment, noble metal loading, space velocity, and gas composition were varied to elucidate their effects on the measured activity and selectivity profiles and to gain insights into the underlying reaction mechanism. A moderate interaction with the support and the formation of small Pt nanoparticles were identified as essential for NO x conversion at low temperatures. Accordingly, TiO₂-supported catalysts were found to be superior in terms of NO x conversion and N 2 yield compared to the CeO₂-supported samples. Highly dispersed Pt species as present on strongly interacting supports are also highly sensitive to H 2 O and O 2 inhibition. Acidic promoters broaden the activity window, while basic dopants shift and narrow the NO x conversion window toward higher temperatures. Nevertheless, the presence of basic sites on the catalyst surface improves the N 2 selectivity over the entire operating temperature window and contribute to NH 3 formation as a secondary byproduct. • Pt nanoparticles on TiO 2 needed, more relevant for activity than dispersed species on CeO 2 . • A mild reductive treatment improves activity of CeO 2 -supported catalysts. • Acidic promoters extend the activity window for NO x removal. • Basic promoters shift activity to higher temperatures, broaden N 2 selectivity window. • NH₃ emissions in presence of basic promoter, N 2 O formation independent of promoter.