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Diesel Oxidation Catalyst for Purifing Exhaust Gas

Diesel Oxidation Catalyst (DOC) is used to remove CO and hydrocarbons using oxygen (5-15% of the gas) in the exhaust gas. It will also oxidize NO to NO2, which, if not controlled, will cause the NO2 level at the outlet of the exhaust pipe to rise.

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Description:

Diesel Oxidation Catalyst (DOC) is used to remove CO and hydrocarbons using oxygen (5-15% of the gas) in the exhaust gas. It will also oxidize NO to NO2, which, if not controlled, will cause the NO2 level at the outlet of the exhaust pipe to rise. In fact, this is controlled by defining the appropriate catalyst formulation, size, and PGM loading. Diesel oxidation catalysts can form N2O as a hydrocarbon-lean NOx reaction product, although some hydrocarbon-lean NOx systems, such as silver-based systems, do not form large amounts of N2O.

Working Principle of Diesel Oxidation Catalyst:

Nitrogen oxides (NOx) emitted by automobiles and stationary sources can cause serious environmental problems. Automotive exhaust gas after-treatment systems are usually based on precious metal catalysts (three-way or diesel oxidation catalysts). One of the undesirable effects of using these catalysts to reduce NOx is the formation of N2O, which is now also regarded as an environmental pollutant [1,2]. In this report, the formation of N2 and N2O during the decomposition or reduction of NOx on Pt/alumina is studied.

For a long time, it has been established that platinum is active in the decomposition and reduction of NO [3-6], and this reaction will be inhibited by oxygen [7-10]. According to reports, in the presence of NO and O2, N2 is formed on platinum according to the following elemental reaction steps [3,4,7]:

(1)NO+∗⇄NO∗

(2)NO∗+∗⇄N∗+O∗

(3)2N∗→N2+2∗

In these reaction equations, free surface sites are indicated by an asterisk.

Diesel Oxidation Catalytic Converter

Until now, the formation of N2O has not been well studied [7], but it is reported that N2O is only weakly adsorbed on platinum [11] and platinum is not an active N2O decomposition catalyst [1,16]. Generally, different mechanisms and pathways for the formation of N2O on platinum in the presence of NO and O2 are considered:

(4)2N∗+O∗⇄N2O∗+2∗

(5)N∗+NO⇄N2O∗

(6)NO∗+NO∗⇄N2O∗+O∗

(7)N∗+NO∗⇄N2O∗+∗

The results show that some of the above reaction pathways can be excluded from the results of this research report.

Common Size:

ITEM Size Hole density
DOC 01 Dia 80*100 mm 200-400 cpsi
DOC  02 Dia 110*100 mm 200-400 cpsi
DOC 03 Dia 130*100 mm 200-400 cpsi
DOC 04 Dia 160*100 mm 200-400 cpsi
DOC 05 Dia 180*100 mm 200-400 cpsi
DOC 06 Dia 250*100 mm 200-400 cpsi
DOC 07 Dia 300*100 mm 200-400 cpsi
DOC 08 Dia 190.5*254 mm 200-400 cpsi
DOC 09 Dia 190.5*305 mm 200-400 cpsi
DOC 10 Dia 240*152.4 mm 200-400 cpsi
DOC 11 Dia 240*254 mm 200-400 cpsi
DOC 12 Dia 240*305 mm 200-400 cpsi