Catalyst ‘light-off’ experiments on a diesel oxidation catalyst connected to a diesel engine—Methodology and techniques

Manipulating modern diesel engine particulate emission characteristics through butanol fuel blending and fuel injection strategies for efficient diesel oxidation catalysts

“…Modern engine after-treatment systems consist of different components such as the diesel oxidation catalysts (DOC) and diesel particulate filters (DPF) [20]. DOCs have a honeycomb monolith shape with high cell density (large surface area) and suitable loadings of a catalytic material such as platinum and/or palladium that is able to almost eliminate CO, HC and much of the particulate organic fraction [16,20,21]. DOC also oxidise NO to produce NO 2 that can then be utilised in the DPF to passively oxidise soot at low temperatures [16,22,23].…”

Critical Review of Low-Temperature CO Oxidation and Hysteresis Phenomenon on Heterogeneous Catalysts

“…Recent CO oxidation studies during heating followed by cooling cycles have shown hysteresis behavior, with higher conversions during extinction [5,49,52,56,[66][67][68][69][70][71][72][73]. Yap et al described that the ignition-extinction hysteresis occur following the steps listed herein: (1) adsorption of CO at low temperatures; (2) ignition when CO starts to desorb from a catalyst surface; (3) CO and O adsorption on the active sites and surface reactions take place between adsorbed CO and O; (4) trigger an increase in the reaction rate; (5) stability during high reactive state and a balance between heat generation and the heat losses; (6) interaction of the CO more strongly with the surplus oxygen allowed by the oxygen covered surface at high temperatures which enhances reactivity by lowering activation energy; (7) high and stable reaction rate due to the enhanced reactivity between adsorbed CO and the high oxygen coverage as the catalyst temperature drops which gives rise to a hysteresis phenomenon or having two values of reaction rates at the same temperature [74].…”

“…Increasing CO concentration in inlet gas causes a higher light-off temperature or ignition point, the hysteresis loop increases upon increasing the CO concentrations [52,56,74,77,87,126,142] Inlet Temperature Ignition and extinction shifted to higher temperatures with rapid increase in CO conversion [77,[128][129][130][131][132][133][134] Surface Contamination and Aging Increase in the hysteresis width due to the removal of contamination that blocks active sites [75,94,141] [55, 94,140] Rate of temperature ramp-up Increase in the temperature ramp-up result in shifting the ignition curve to higher temperatures [72,92] Inhibition parameters Different inhibiting species accumulation on catalyst surface can change the shape of hysteresis curves and increase the width of the hysteresis. [141,142].…”

Model-based passive and active diagnostics strategies for diesel oxidation catalysts

“…Effective monitoring time is then ruled by enabler conditions which depend on engine operating points, system dynamics and catalyst temperature. These enabler conditions in the proposed strategy are: -The DOC is sufficiently hot, since the light-off temperature sets the minimum temperature from which the DOC is able to oxidise [24,25]. -There is sufficient exhaust mass flow.…”