Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

Sensors

关键词: on-board diagnosis (OBD);    lambda probe;    three-way catalyst (TWC);    microwave;    ammonia SCR;    lean NO_x trap (LNT);   

DOI  :  10.3390/s100706773

来源: mdpi

【 摘 要 】

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NO_x traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NO_x-loading of lean NO_x traps, and the soot loading of Diesel particulate filters.

【 授权许可】

CC BY   
© 2010 by the authors licensee MDPI, Basel, Switzerland.