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 H₂-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 insight 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 N₂ yield compared to the CeO₂-supported samples. ... mehrHighly dispersed Pt species as present on strongly interacting supports are also highly sensitive to H₂O and O₂ inhibition. Acidic promoters increase the activity window, while basic dopants shift and narrow the NO_x conversion window toward higher temperatures, the addition of acidic dopants results in the opposite effect. Nevertheless, the presence of basic sites on the catalyst surface improves the N₂ selectivity over the operating temperature window and contribute to NH₃ formation as secondary byproduct.