Novel Electrification Strategy for Low-Temperature NOx Removal

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NO_x storage–reduction (NSR) is a promising approach for controlling NO_x emission from diesel vehicles, thus to address the growing global energy crisis and climate change.

However, due to the improvement of engine technologies and frequent idling in traffic, the exhaust temperatures usually below 250 ℃, which is too low for catalytic NO_x conversion to occur.

To address this issue, researches at NIMTE develop a novel electrified NSR strategy. Pt and K co-supported antimony-doped tin oxides (Pt-K/ATO) serve as conductive catalysts. With C₃H₆ as a reductant, a low input power (0.5−4 W) is applied to the catalyst to trigger NSR reactions.

By virtue of this strategy, the ignition temperature for 10% NO_x conversion decreased to 165 °C, which is nearly 100 °C lower than that of the traditional thermal counterpart.

To optimize the power configuration, the power in the fuel-lean period was reduced, leading to a 23% increase in the maximum energy efficiency.

In addition, electrically driven release of lattice oxygen from catalysts is revealed to play crucial roles in NSR reactions, including promoting NO oxidation for NO_x adsorption, O₂ evolution for NO_x desorption, as well as C₃H₆ activation for NO_x reduction, thus greatly improving NSR performance.

As reported in the previous work of the research group, this effect has also been applied to the catalytic soot combustion, showing its certain universality.

This electrification strategy may shed light on hybrid vehicle design, especially on electronic control unit development, as the electric power input can be adjusted in real time to reduce exhaust pollutants.