Diesel Oxidation Catalyst

By | July 31, 2017

According to research, United States has been using diesel oxidation catalysts with commercial vehicles since 1991. The name comes from its ability to oxidize several gas components in the exhaust using oxygen. The main function of this catalyst is to change harmful and dangerous diesel pollutants into harmless products. Any country that is fully grown considers this catalyst very important in reducing environmental pollution.

Basically, what you can capture fast about DOC is:

  • It converts carbon monoxide and hydrocarbons to water and carbon dioxide
  • It oxidizes very harmful particulates into harmless byproducts.
  • It eliminates most of the muffler requirement.

But how does diesel oxidation catalyst (DOC) really work?

How Diesel Oxidation Catalyst Works

DOC simply enhances chemical oxidation of diesel pollutants which include: Carbon Monoxide (CO), hydrocarbons that are gas phased (HC) and Sulfate Organic Formations (SOF). These are the 3 main byproducts released by diesel engines.

It is worth noting that there is also Sulfur Dioxide (SO2) in diesel that is as a result of combustion of fuels that contain sulfur. SO2 is oxidized to Sulfur trioxide (SO3) and when SO3 is hydrated it gives forth Sulfuric acid, which may be considered as an undesirable product.

Another undesirable emission is the oxidation of NO to NO2 which is more toxic and it reduces the quality of the air. The control systems of the current diesel emission have designed oxidation catalyst to produce high levels of Nitrogen dioxide (NO2).

Hydrocarbons form Carbon dioxide and water in form of vapor when it passes through the catalyst. Carbon Monoxide is oxidized to produce carbon dioxide. Generally, water and carbon dioxide is the main byproducts after oxidation. They are considered as harmless to the environment.

  • Catalytic Reactions

The above can be captured in the following chemical reactions:

For Sulfur Dioxide:

2SO2 + O2 = 2SO3

SO3 + H2O = H2SO4

For Nitrogen Trioxide:

NO + 1/2O2 = NO2


For Hydrocarbons:

(Hydrocarbons) + O2 = CO2 + H2O

For Carbon monoxide:

CO + 1/2O2 =CO2

In summary catalytic reactions involves three main stages:

  1. Incorporation of Oxygen to the catalytic sites
  2. The reaction of various reactants like carbon monoxide, sulfurs, and hydrocarbon take place. This reaction is called oxidation. These reactants mix with oxygen to emit various byproducts like water, carbon dioxide, and various sulfurs.
  3. Reaction changes anything harmful in nature into harmless products which diffuse through the exhaust gas.

  • Benefits of Diesel Oxidation Catalyst

As you may have noticed DOC comes along with lots of benefits that both beneficial to the environmental conservancy and human health. It is, therefore, necessary you make sure your diesel engine is fitted with the oxidation catalyst whether you are using it on or off the road.

Some of the benefits of DOC include:

  1. It oxidizes diesel pollutants into harmless products like water and carbon dioxide. This reduces air pollution consequently reducing respiratory diseases like asthma and cancer that are as a result of carbon monoxides and sulfur oxides.
  2. It oxidizes various non-regulated emissions like aldehydes. This helps in reduction of odor that comes along with gases from diesel exhaust.

In conclusion, therefore, any person who minds the well-being of other people should fit their diesel engines with Diesel Oxidation Catalyst. You will save a life of your friend by doing that. It is worth it.