NOx Adsorber Aging on a Heavy-Duty On-Highway Diesel Engine - Part One

A 5.9-liter medium-heavy-duty diesel engine, equipped with a diesel exhaust emission control system consisting of catalyzed diesel particulate filters and NO_x adsorber catalysts arranged in a dual flow path configuration was evaluated with the goal of studying the thermal aging characteristics of a number of NO_x adsorber formulations. These adsorbers were tested with near zero sulfur fuel and low sulfur engine oil to minimize the impact of sulfur poisoning on the test results. Testing was performed at a high temperature engine operating mode to provide accelerated but not abusive aging. The test duration ranged from 100 to 250 hours depending on the severity of the aging at the 100 hour mark. The initial “zero” sulfur testing screened the NO_x adsorber formulations for future testing and established a thermal aging baseline.