An integrated solution for NO x ‐reduction and ‐control under lean‐burn conditions

Upcoming emission regulations order highly effective NO x ‐reduction systems in lean‐burn engines requiring new catalytic materials and integrated control of the reduction process. Thus, new approaches for NO x ‐reduction and its monitoring over an On‐Board‐Diagnostic (OBD) system are suggested throughout the globe. A promising attempt is the development of a catalytic system having an integrated NO x ‐sensor, based on selective catalytic reduction process and impedance sensors. The study displays the results achieved both with a perovskite type of self‐regenerative catalyst functioning by H 2 ‐reductant and with impedance NO x ‐sensors. The catalysts were tested at the temperature range of 150 °C to 360 °C yielding NO x conversion rates of 92 % with high selectivity to N 2 . Impedance sensors having NiCr 2 O 4 ‐ and NiO‐SE and PYSZ‐ and FYSZ‐electrolytes are developed and tested at 600 °C under lean atmosphere (5 vol. % O 2 ). Better sensing behaviour towards NO and lower cross‐selectivity towards O 2 , CO, CO 2 and CH 4 have been observed with sensors having NiO‐SE.