Abstract
Pt-based catalysts exhibit excellent low-temperature activity in the selective catalytic reduction of NO (x) with H(2) (H(2)-SCR), but their tendency to form N(2)O poses a significant challenge for practical use. This issue is further complicated by unclear formation mechanisms, hindering the development of more efficient catalysts. This study explored the N(2)O generation mechanisms on Pt catalysts supported by MgO, Al(2)O(3), SiO(2), and TiO(2), aiming to achieve a deep understanding that could advance the Pt catalysts with high NO (x) conversion and minimized N(2)O emissions. Through systematic kinetics and characterization analyses, the direct influence of the support acidity and reactant dynamics (O(2) and NO) on N(2)O formation was clearly revealed. Notably, the Pt catalysts with strong NO adsorption capacity showed reduced N(2)O generation, highlighting the critical role of NO adsorption sites in the H(2)-SCR process. By incorporation of NO adsorption sites (i.e., MgO, BaO, CeO(2)) onto Pt/SiO(2), both the H(2)-SCR efficiency and N(2) selectivity (reduced N(2)O selectivity) were significantly enhanced, effectively reducing the N(2)O emissions through optimized surface NO adsorption. These findings provide a design framework for more selective Pt-based catalysts, advancing H(2)-SCR systems for effective NO (x) abatement from hydrogen-internal combustion engines, which is a promising carbon-free transportation technology.