Influence of catalyst supports on H2-SCR catalysts: A combined experimental and modeling approach including mass transfer

Journal article, 2026

NO selective reduction by H2 (H2-SCR) has been developed as a promising technology for the emission control for H2 combustion engines. This work focused on experimentally evaluating the effect of catalyst supports by performing material characterization, followed by the development of a kinetic model that incorporated mass transfer effects. 1 wt% Pd catalysts supported on Al2O3, TiO2, BEA zeolite, and SSZ-13 zeolite were prepared and H2-SCR performance tests were performed across the temperature range of 100–300 °C, under varying H2/NO ratios and both dry and wet conditions. The Pd/TiO2 sample was found to exhibit the highest performance for NO conversion and N2 yield. Material characterization confirmed its larger Pd particle size and lower dispersion helped suppress the competing H2 oxidation reaction; the presence of reduced-state Pd promoted catalytic conversion; and the Pd/TiO2 chemical properties facilitated hydrogen spillover. In the kinetic model, reactions involving NO reduction to N2, N2O, and NH3, as well as H2 oxidation, were simulated, accurately reproducing the experimental trend and values for all the samples. NH3 formation was observed only on the Pd/TiO2-supported catalyst and was found to be independent of NO concentration. The kinetic parameters for the different samples were consistent with both the catalytic performance and material characterization results. Moreover, the study showed that external mass transfer played a crucial role by suppressing the fast hydrogen oxidation reaction, thus enhancing hydrogen availability for NO reduction.