Diesel oxidation catalyst: A comprehensive history

The diesel oxidation catalyst (DOC) can reduce emissions by up to 90%, making it an important part of any process that uses diesel fuel for power or propulsion, such as marine engines and generators. This article will take a look at the DOC and some of its history.

DOCs, or diesel oxidation catalyst, play an important role in reducing emissions from large marine engines and generators. The DOC is a porous ceramic that acts as a catalyst by speeding up burning off unburned fuel particles through combustion to produce carbon dioxide and water vapor.

History of DOC:

Robert Huber first developed dOCs at BASF in the early 1970s. The production process involved taking a ceramic carrier, loading it with rhodium and vanadium salts (the catalysts), firing it at high temperatures to form the catalyst, then using pressurized ammonia to wash away excess salt.

The DOC was much more effective than previous methods for removing pollutants like nitrous oxides from diesel engines. As a result, it was widely implemented in the ’80s and ’90s by many heavy equipment manufacturers, such as Caterpillar, Volvo Penta, Scania AB, MAN B&W Diesel A/S, and Wärtsilä, among others.

In recent years, several studies have been conducted to test whether or not DOCs are effective at reducing emissions. These studies have come to conflicting conclusions about their effectiveness. Still, it is generally agreed that they do not perform as well in the real world as anticipated based on laboratory testing.

Criticism concerning emissions testing:

This is not surprising. A common criticism of emissions testing, in general, is that it doesn’t accurately represent real-world conditions since most tests are performed on new vehicles with fresh engines running for a short period at steady speeds under ideal conditions. The EPA has attempted to address this problem by moving towards more realistic test cycles and equipment, but there is still a long way to go.

For these reasons, it’s not easy to say whether or not DOCs are more effective than other emissions control systems. However, anecdotal evidence says they work under real-world conditions, given enough time for the catalyst to act on unburned fuel particles in the exhaust stream after combustion. Still, science has yet to prove this.


In short, diesel oxidation catalysts are a pretty good way to reduce emissions from large marine engines and generators. In some cases, they are more effective than other emission control methods used for stationary sources of pollution such as power plants. Still, they don’t seem quite as reliable when you consider the variability in engine performance over time.

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