A mixed potential based sensor that measures directly catalyst conversion-A novel approach for catalyst on-board diagnostics

Almost all diesel engines are equipped with a diesel oxidation catalyst (DOC). It is one task of the DOC to oxidize hydrocarbons. Its conversion efficiency has to be monitored during operation (on-board diagnostics, OBD). In contrast to approaches that use one hydrocarbon sensor downstream of the DOC, we suggest a novel concept to determine in operando and directly the conversion rate of such a catalyst. This conversion rate sensor (CRS) bases on the mixed potential principle, and compares the gas atmospheres up- and downstream of the catalyst directly within one single device. To prove this concept, an initial laboratory setup was set up. It is shown that the sensor responds to the conversion rate as expected with a CRS characteristic that follows theoretical expectations.