On-board hydrogen production from urea via electrolysis to promote low-temperature catalytic reduction of NOx emissions

Abstract

Nitrogen oxides emissions pose a significant environmental challenge, particularly in heavily industrialized, high-traffic regions. Global NO_x levels continue to rise, despite various aftertreatment techniques being deployed to mitigate emission levels of combustion engine vehicles. Novel approaches to enhance NO_x conversion efficiency at low exhaust temperatures (< 200 C) include integrating hydrogen and ammonia injection before selective catalytic reduction modules. Urea electrolysis presents a promising avenue for simultaneous hydrogen and ammonia production. An anion exchange membrane electrolyser emerges as a viable and low-cost solution for on-board hydrogen production, offering compact size and compatibility with existing vehicle systems. Overcoming challenges such as catalyst and component selection, electrolyte viability, and system integration remains critical for realising the full potential of electrolysis-based NO_x mitigation strategies in passenger vehicles.