System and method for creating catalyst obd limit parts for exhaust aftertreatment applications

Abstract

Catalyst diagnostic limit parts and methods for making catalyst diagnostic limit parts are disclosed. An exemplary catalyst diagnostic limit part includes a substrate and a washcoat coating the substrate. The washcoat includes an active catalyst and an inactive catalyst at a predetermined ratio of active catalyst to inactive catalyst so as to control the performance of the catalyst diagnostic limit part.

What is claimed is: 
     
         1 . A catalyst diagnostic limit part, comprising:
 a substrate; and   a washcoat coating the substrate, the washcoat including an active catalyst and an inactive catalyst at a predetermined ratio of active catalyst to inactive catalyst so as to control the performance of the catalyst diagnostic limit part.   
     
     
         2 . The catalyst diagnostic limit part of  claim 1 , wherein the predetermined ratio is no higher than 30%:70%. 
     
     
         3 . The catalyst diagnostic limit part of  claim 1 , wherein the predetermined ratio is no higher than 25%:75%. 
     
     
         4 . The catalyst diagnostic limit part of  claim 1 , wherein the inactive catalyst is prepared by thermal aging an active catalyst. 
     
     
         5 . The catalyst diagnostic limit part of  claim 1 , wherein the inactive catalyst includes a chemically-inert material. 
     
     
         6 . The catalyst diagnostic limit part of  claim 5 , wherein the chemically-inert material includes un-exchanged zeolites. 
     
     
         7 . The catalyst diagnostic limit part of  claim 1 , wherein the substrate has a length to diameter ratio of at least 0.33. 
     
     
         8 . The catalyst diagnostic limit part of  claim 1 , wherein the substrate is fully-coated by the washcoat. 
     
     
         9 . The catalyst diagnostic limit part of  claim 1 , wherein the catalyst diagnostic limit part is a diesel oxidation catalyst. 
     
     
         10 . The catalyst diagnostic limit part of  claim 9 , wherein the washcoat includes a predetermined amount of platinum group metal loading less than a conventionally-full amount, the predetermined amount defining the predetermined ratio. 
     
     
         11 . The catalyst diagnostic limit part of  claim 1 , wherein the catalyst diagnostic limit part is one of a selective catalytic reduction catalyst, a selective catalytic reduction catalyst on filter, and an ammonia oxidation catalyst. 
     
     
         12 . The catalyst diagnostic limit part of  claim 11 , wherein the washcoat includes a predetermined amount of active catalyst loading less than a conventionally-full amount, the predetermined amount defining the predetermined ratio. 
     
     
         13 . The catalyst diagnostic limit part of  claim 1 , wherein the catalyst diagnostic limit part includes each of a diesel oxidation catalyst and a diesel particulate filter. 
     
     
         14 . The catalyst diagnostic limit part of  claim 1 , wherein the substrate is a flow-through substrate. 
     
     
         15 . The catalyst diagnostic limit part of  claim 1 , wherein the substrate is a wall-flow substrate. 
     
     
         16 . An on-board diagnostic (OBD) limit test system, comprising:
 an exhaust gas source;   a catalyst diagnostic limit part fluidly coupled to the exhaust gas source and configured to receive exhaust gas from the exhaust gas source, the catalyst diagnostic limit part including a substrate and a washcoat coating the substrate, the washcoat including an active catalyst and an inactive catalyst at a predetermined ratio of active catalyst to inactive catalyst so as to control the performance of the catalyst diagnostic limit part;   a plurality of exhaust gas sensors configured to measure operational parameters of the exhaust gas; and   an OBD system operably coupled to the exhaust gas sensors, the OBD system configured to detect a malfunction of the catalyst diagnostic limit part.   
     
     
         17 . The OBD limit test system of  claim 16  wherein the predetermined ratio is no higher than 30%:70%. 
     
     
         18 . The OBD limit test system of  claim 16 , wherein the predetermined ratio is no higher than 25%:75%. 
     
     
         19 . The OBD limit test system of  claim 16 , wherein the substrate has a length to diameter ratio of at least 0.33. 
     
     
         20 . The OBD limit test system of  claim 16 , wherein the substrate is fully coated by the washcoat.