Ammonia Creation and Conversion Technology uses freed ammonia to break down NOx leaving nitrogen and water with tests showing a 98% efficiency before application specific fine tuning.
https://www.autocar.co.uk/car-news/industry/diesel-saving-technology-could-make-it-market-two-years
https://www.autocar.co.uk/car-news/industry/diesel-saving-technology-could-make-it-market-two-years