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

NO selective reduction by H 2 (H 2 -SCR) has been developed as a promising technology for the emission control for H 2 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 Al 2 O 3 , TiO 2 , BEA zeolite, and SSZ-13 zeolite were prepared and H 2 -SCR performance tests were performed across the temperature range of 100–300 °C, under varying H 2 /NO ratios and both dry and wet conditions. The Pd/TiO 2 sample was found to exhibit the highest performance for NO conversion and N 2 yield. Material characterization confirmed its larger Pd particle size and lower dispersion helped suppress the competing H 2 oxidation reaction; the presence of reduced-state Pd promoted catalytic conversion; and the Pd/TiO 2 chemical properties facilitated hydrogen spillover. In the kinetic model, reactions involving NO reduction to N 2 , N 2 O, and NH 3 , as well as H 2 oxidation, were simulated, accurately reproducing the experimental trend and values for all the samples. NH 3 formation was observed only on the Pd/TiO 2 -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.