Diesel soot abatement

Diesel soot emissions can be reduced by two different end-of-pipe technologies  

As an example of the performance of such a diesel particulate trap, a spontaneous filter regeneration is shown in Fig. 15.3. 

The pressure drop over the filter increases continuously with time until the moment, when a critical soot load has accumulated on the filter surface. Self-ignition of the soot then occurs, which in addition depends on the exhaust gas temperature, the filter temperature, the oxygen concentration, the type and amount of the volatiles adsorbed onto the carbonaceous soot matrix, and the packing density of the soot on the filter surface. The soot-laden filter bums free, the pressure drop decreases and the loading/regeneration cycle repeats itself again, as shown in Fig. 15.4. 

in 2004, the reactive diesel soot filter finally seems to have become a state-of-the-art technology (Tabs. 15.1 and 15.2). 

The question remains - why did it take so long from the laboratory to the market The answer comprises three reasons  

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Table 15.1. Diesel cars available on the German market with diesel soot abatement. Data taken from the web, ADAC Germany, spring 2004.

Table 15.2. Different methods of diesel soot abatement the state of the art. ...

CERIUM AND PLATINUM BASED DIESEL FUEL ADDITIVES IN THE DIESEL SOOT ABATEMENT TECHNOLOGY... 

The use of CeOs-based materials in catalysis has attracted considerable attention in recent years, particularly in applications like environmental catalysis, where ceria has shown great potential. This book critically reviews the most recent advances in the field, with the focus on both fundamental and applied issues. The first few chapters cover structural and chemical properties of ceria and related materials, i.e. phase stability, reduction behaviour, synthesis, interaction with probe molecules (CO. O2, NO), and metal-support interaction — all presented from the viewpoint of catalytic applications. The use of computational techniques and ceria surfaces and films for model catalytic studies are also reviewed. The second part of the book provides a critical evaluation of the role of ceria in the most important catalytic processes three-way catalysis, catalytic wet oxidation and fluid catalytic cracking. Other topics include oxidation-combustion catalysts, electrocatalysis and the use of cerium catalysts/additives in diesel soot abatement technology. 

Biamino, S., Fino, P., Fino, D., Russo, N, and Badini, C. (2005) Catalyzed traps for diesel soot abatement in situ processing and deposition of perovskite catalyst Appl Catal. B Environ., 61 (3-4), 297 305. 

The term catalytic combustion generally means a complete oxidation of hydrocarbons to C02 and H20 over solid catalysts. Catalyst technology for air-pollution control such as exhaust gas treatment, abatement of the emission of VOCs, combustion of diesel soot particles, and high temperature combustion have boosted research in catalytic combustion. 

Soot particles are emitted by diesel engines together with NO, CO, and unburned hydrocarbons (HCs) in gas streams with high O2, CO2, and H2O concentrations and temperatures typically below 500-550 °C Under these conditions, CO and HC oxidation can be easily accomplished with a diesel oxidation catalyst (DOC), but both NO and soot require complex abatement strategies. 

Milt, V. G. Pissarello, M. L. Miro, E. E. et al. Abatement of diesel-exhaust pollutants NOx storage and soot combustion on K/La203 catalysts. Appl. Catal. B Environ. 2003, 41,397-414. 

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