Combustion of diesel soot

Catalytic combustion of diesel soot particulates over LaMnOs perovskite-type oxides prepared by malic acid method has been studied. In the LaMn03 catalyst, the partial substitution of alkali metal ions into A site enhanced the catalytic activity in the combustion of diesel soot particulates and the activity was shown in following order Cs>K>Na. In the LarxCs MnOj catalyst, the catalytic activity increased with an increase of X value and showed constant activity at the substitution of x>0.3... 

In the following sections, the different types of reactive filters, together with their typical applications, will be presented. The separation and catalytic combustion of diesel soot is the most important and furthest investigated application. Consequently, this type of reactive filtration, with its practical and theoretical aspects, will form the main focus of this chapter. 

Fig. 15.5. Typical pressure drop and concentration-time curves of a diesel particulate trap in a closed gas-loop experiment with constant heating rate for the characterization of catalyst or filter performance for the combustion of diesel soot. Sintered SiC ceramic filter, without catalyst coating or fuel additive (from Ref. [46]).

Wang et al. reported sol-gel preparation of Lai K cMn03 NPs, and examined their catalytic activity for the combustion of diesel soot particles (Wang et al., 2005a). It was foimd that as the K content increases, the combustion temperature decreases, and the samples with x = 0.20 and 0.25 are good candidate catalysts for the soot particle removal reaction under loose contact conditions. 

Investigation of copper-cerium oxide catalysts in the combustion of diesel soot... 

The combustion of diesel soot has been studied in presence of copper-cerium oxide catalysts. These catalysts were prepared by impregnation of copper nitrate on ceria and calcination under air up to 1073 K. The solids were widely characterised by electron paramagnetic resonance (EPR) technique. For an atomic ratio Cu/Ce=l and a calcination temperature of 673 K, the catalyst seems to be t e most active in the combustion of diesel soot, when compared to other catalysts. The Cu monomers are more concerned than the dimers in this combustion. 

The purpose of this work is to study the catalytic properties of different copper-cerium oxides in the combustion of diesel soot and to correlate their activities with the nature of copper species present in the catalyst. 

The catalytic combustion of Diesel soot was studied performing reactivity tests of soot-catalyst mixtures in a tubular flow reactor. The dependence of the reaction rate on the temperature was found. With respect to the uncatalysed combustion the reactivity of the soot in the presence of catalyst increased of some orders of magnitude while the apparent activation energy was found to be less than half. 

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. 

CATALYTIC COMBUSTION OF DIESEL SOOT ON PEROVSKITE TYPE OXIDES... 

Comparison between oxides of copper, manganese, chromium and vanadium shows that V2O5 is one of the most active catalysts for the combustion of diesel soot [10]. Catalyst made up of V2O5 and CuO with a molar fi"action 0.9 in vanadium leads to an enliancement of the activity [11]. Another screening study on oxides of potassium, vanadium, copper, manganese and cobalt shows that the systems (K-V-O) and (K-Cu-0) can reduce the ignition temperature of carbon black of about 260°C [12]. It is to be noticed that no study about the stability of these compounds is reported. 

Stability of K- LaiOs catalysts during the combustion of Diesel soot. High Frequency CO2 Pulses and soot - catalyst contacting studies... 

The catalysts to be used in the combustion of diesel soot, must be stable to high temperatures and the presence of other combustion products. The activity should be high enough at temperatures as low as 200°C for low charge diesel engines, unless an external heating power is supply to the catalytic filter. In any case, the catalyst stability is a key factor in determining its applicability in a commercial scale. 

Some examples of lanthana as catalysts included the dehydration/dehydrogenation of ethanol [21], the NOx decomposition [4], the NO reduction by methane [22], the oxidative coupling of methane [23, 24] and the combustion of diesel soot [25], As perovskites, the lanthanum compounds showed catalytic activity in fuel combustion [26], carbon monoxide hydrogenation [27], dry reforming of methane [28-30], and partial reforming of methane [31],... 

Pisarello, M. L., Saux, C., Miro, E. E. Querini, C. A. (2001). Stability of K-La203 catalysts during the combustion of Diesel soot. High frequency CO2 pulses and soot-catalyst contacting studies. Stud. Surf. Set. Catal, 139,141-148. 

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