Automotive Exhaust Emissions
Is blue technology green enough yet? DeNOx technologies currently used for on-road diesel vehicles are not where they should be. This has become clear not only because of recent scandals but is evident when looking at long term trends of on-road emission data which proved that gasoline vehicles followed the NOx emission limits which were lowered by 95% from 1990 to 2009. The opposite was found for diesel passenger cars and light duty vehicles. On road measurements indicate that NOx emissions, especially those of toxic and highly reactive NO2 have increased from 1990 until 2005 and are only slowly decreasing and one order of magnitude higher than those of comparable gasoline vehicles.
These findings indicate that deNOx technologies in real world operation are not efficient enough and have to be improved considerably. It is evident that current deNOx technologies emit toxic and environmentally relevant reactive nitrogen compounds like NO2, NH3, HNCO and N2O. These compounds contribute to the overall exhaust toxicity but are not limited by current vehicle legislation which lacks behind here.
Like for particle filters, Advanced Analytical Technologies and partners have established specific analytical procedures to assess the efficiency of deNOx technologies and to monitor secondary emissions like NO2, NH3, HNCO and N2O. Research is also expanding towards alternative exhaust treatment technologies for secondary emissions, such as Oxicat, DPF, GPF, SCR, etc.
In 2020 more than 50 million gasoline direct injection (GDI) vehicles may circulateon European roads. The majority of these vehicles will not be equipped with particle filters and will release trillions of inhalable, persistent and toxic nanoparticles smaller than 100 nm. In the GASOMEP project we study several GDI vehicles under transient and steady driving conditions with varying converter technologies and fuels. With industrial partners, we study prototype gasoline particle filters (GPFs).
Our focus is on emissions of toxic and environmentally relevant pollutants. Particle characterization included size, number distribution and metal content. Emissions of carcinogenic compounds, especially the polycyclic aromatic hydrocarbons (PAHs) and their nitrated forms are studied to assess the genotoxic potential of these exhausts and the effectiveness of filters on particles and carcinogenic compounds. In addition, the secondary organic aerosol formation of GDI exhausts is investigated in smog chamber and flow reactor experiments to assess the impact on secondary ambient particle formation.