Influence of supporting materials on the deactivation of diesel exhaust catalysts

Abstract

Two kinds of vehicle-aged diesel oxidation catalysts were analyzed. The phase transition of alumina as a support and Pt sintering after a long-time operation caused serious deactivation of the catalysts.

Spatially-Resolved Temperature and Gas Species Changes in a Lean-Burn Engine Emissions Control Catalyst

“…2 ; the Al 2 O 3 loading was 1.63 g/in. 3 ; and the Pt loading was 49.9 g/ft 3 . A FLIR Merlin Mid InSb MWIR (midwave infrared) camera fitted with a FLIR 50 mm lens was mounted vertically above the reactor and imaged the flat surface of the catalyst through the sapphire window.…”

“…DOCs are commonly composed of Pt supported on Al 2 O 3 , with zeolite and Pd components sometimes added. [2][3][4] There have been several studies that characterized temperature and reaction gradients to spatially resolve reactivity details with catalysts similar in composition to DOCs. Observations by Sun et al included temperature hysteresis during CO oxidation ignition and extinction studies on Pt, in which feed concentration perturbations caused shifts in the position of the reaction zone within the monolith, and the size of the concentration steps affected the width of the zone and velocity of the temperature and light-off wave to the catalyst front.…”

“…Diesel oxidation catalysts (DOCs) are commonly placed in diesel engine exhaust gas aftertreatment systems, with targeted reactions including CO, hydrocarbon, and NO oxidation. DOCs are commonly composed of Pt supported on Al 2 O 3 , with zeolite and Pd components sometimes added. − …”