Pt-based catalysts for NOx reduction from H2 combustion engines

Journal article, 2024

Platinum supported on SSZ-13 zeolite has been found to be a potential catalyst for the selective catalytic reduction of NO by H-2. This work has studied the effects of the H-2/NO molar feed ratios (0/4.4/8.8/13.2) and the impact of water on the performance of the H-2-SCR of NO on the Pt/SSZ-13 catalyst. A higher H-2/NO ratio promoted the start of the reaction at lower temperatures and favoured the production of N-2. The effect of Pt loadings was also studied with three loadings of 0.5/1.0/2.0 wt%. It was found that the 0.5 wt% Pt sample displayed the highest N-2 selectivity of 75%. In addition, an inhibiting effect of water for H-2-SCR at low temperatures was proved. Pt/SSZ-13 has shown good hydrothermal durability after 6 h in total ageing pretreatment at 800 degrees C and interestingly the nitrogen formation even increased. The support effect of SSZ-13, BETA and Al2O3 on H-2-SCR was evaluated in terms of catalytic performance and their catalytic durabilities by hydrothermal ageing experiments, showing that zeolites are significantly better for H-2 SCR. In situ DRIFT measurements helped to explore the mechanism of H-2-SCR on the Pt catalyst. A careful design of the measurements was used to distinguish the overlapping peaks of the water on the DRIFT spectrum. NH4+ ions are formed and it was shown that they play a role as intermediates during the reaction to assist the NO reduction.