New Particulate Matter (PM) and Particulate Number (PN) regulations throughout the world have created a need for aftertreatment solutions that include particulate control as an option to comply with the legislation. However, limitations in other criteria emissions cannot be sacrificed to accomplish the reduction of PM/PN.
For this work, three-way washcoat catalyzed wall-flow Gasoline Particulate Filters (GPF) and similarly catalyzed flow-through catalysts of common defined volume were tested. Their catalytic performance was determined by measuring NOx, CO and HC conversion efficiencies and CO2 levels over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) cycles. Analysis of the impact on CO2 emissions was also evaluated in relation to backpressure from 1-D modeling analysis. All exhaust systems used the same loading and ratio of Platinum Group Metals (PGM), but employed different cell structures in their substrates.
It was observed that replacing the flow-through catalyst with a catalyzed GPF, negatively impacted the system conversion efficiency yielding less effective catalyst volume with varying Geometric Surface Area. This reduction in efficiency necessitates higher volume composition to reach the same conversion efficiency over the regulated drive cycles. As expected, CO2 emissions were found to increase with increasing backpressure for the flow-through and GPF components tested. A method was devised and developed to optimize the integration of a coated GPF into an aftertreatment system for criteria emissions performance while limiting CO2 impacts.