Hysteresis effect study on diesel oxidation catalyst for a better efficiency of SCR systems

Time-dependent hysteresis in the NO oxidation to NO2 on Pt-based catalysts

“…2-5 provides confidence that the observed time-dependent hysteresis behavior is not an experimental artifact, however it sheds little light on its nature. The slow and substantial changes in the catalyst activity suggest that they are triggered by some reversible rearrangements in the catalyst surface, likely driven by the changes in the oxidation state of precious metal sites, in agreement with earlier literature studies [4][5][6][7][8].…”

“…A number of earlier studies have pointed to the complexity observed in the behavior of various DOCs in the reaction of NO oxidation [4][5][6][7][8]. In particular, Olsson et al has reported the NO oxidation performance decreased during NO oxidation reaction over time for as long as 36 h of operation over Pt/alumina catalyst [4].…”

“…It had been widely accepted that the precious metal oxidation state plays significant role in these observations. Other factors, such as size of Pt or Pd particles [5,7] and role of interaction with the support [9][10][11][12][13] have been considered as well.…”

Green shipping: Marine engine pollution abatement using a combined catalyst/seawater scrubber system. 1. Effect of catalyst

“…The type of hysteresis observed in the present case, in which the activity is higher with decreasing temperature than with increasing temperature is considered as a ''normal or regular'' hysteresis [49]. Hysteresis phenomena have been attributed to several factors, for example thermal inertia of the catalyst multiple steady states due either to reaction exotherm or surface or inhibition due to adsorption/desorption phenomena [49], change of the state of the catalyst (oxidised/reduced) [50,51]. Evidence, however, has grown that for strongly exothermic reactions, mass and heat transfer limitations may play a dominant role [52,53].…”

Experimentelle und simulative Untersuchung von Dieseloxidationskatalysatoren bei reversibler Edelmetalloxid-Bildung

“…Zyklisch durchgeführte Light-Off/Light-Out-Versuche mit wechselnden NO/O 2 /N 2 -Zulaufkonzentrationen zeigen eine Hysterese, welche vom Ausmaß her den NOUmsatzhysteresen ähnelt, die auf Pt-DOCs beobachtet werden können [73]. Allerdings verläuft diese auf dem legierten Katalysator regulär und nicht invers.…”