Electric field-assisted NSR process for lean NOx reduction at low temperatures

Abstract

Lean-burn engines are gaining attention for their lower CO₂ emissions, higher thermal efficiency, and improved fuel economy compared to traditional combustion engines. However, they present some difficulty for reducing nitrogen oxides (NO_x) because of residual oxygen. To address this difficulty, NO_x storage reduction (NSR) system, which combines noble metals and NO_x adsorbents, is developed as a viable approach. But it requires cyclic operation, which adversely affects fuel efficiency. A novel approach proposed in this work is electric field-assisted lean NO_x reduction, which applies an electric field to the NSR catalyst during lean conditions. This innovation uses surplus vehicle electricity for exhaust purification, enhances hydrogen transfer, and improves NO_x reduction, even at low temperatures. Tests with a 3 wt% Pt–16 wt% BaO/CeO₂ catalyst demonstrate markedly higher NO_x conversion to N₂ (13.1% vs. 2.9% without an electric field). This process is effective with extended electric field exposure, doubling the conversion rate. Electric field-assisted lean NO_x reduction, by improving NSR technology, can enhance NO_x conversion efficiency, reduce emissions, and optimize fuel efficiency in lean-burn engines.