What Are Diesel Oxidation Catalysts?

Everyone is interested in the distinctions between the various types of catalytic converters. This is because catalytic converters are incredibly valuable scrap components, which generates extra revenue for the automotive industry. All original equipment manufacturer (OEM) catalytic converters from gasoline-powered vehicles can be sold for a good price, but many people are unsure whether diesel converters can be sold with the same success. The diesel oxidation catalyst and diesel particulate filters will be discussed in detail in this article’s discussion of diesel emission control systems.

There are several abbreviations to be aware of when dealing with diesel related automotive components. DOC stands for Diesel Oxidation Catalytic Converter. DPF is an abbreviation for Diesel Particulate Filter. DPR stands for Diesel Particulate Reduction System. SCR is an abbreviation for Selective Catalytic Reduction.

Diesel fuel contains more energy per gallon than gasoline, making it more cost effective overall. Diesel catalytic converters are either two-way catalytic converters with a diesel oxidization catalyst or three-way converters with SCR reduction. Before being released into the atmosphere, diesel engine gases go through the following four processes:

  • Exhaust Gas Recirculation
  • Diesel Particulate Filtration
  • Diesel Oxidization Catalyst
  • Selective Catalytic Reduction

Diesel Oxidation Catalyst
Every modern diesel vehicle contains diesel oxidation catalysts. They are usually the first part to encounter the toxic gases released by the engine. The diesel oxidation catalyst’s function is to convert carbon monoxide into carbon dioxide and decompose unspent fuel. Although it is the smallest unit in the catalytic converter, it is the most valuable because it contains palladium and platinum, which gives it a high recycling value.

Diesel Particulate Filters
These unites, also known as DPFs, deal with the second polluting byproduct of diesel engines that gas engines do not produce: soot, or diesel particulates. DPFs, like diesel oxidation catalysts, contain trace amounts of palladium and platinum to aid to catalysis. Diesel particulate filters are also worth considering recycling due to their palladium and platinum content.

Overall, diesel catalytic converters have a lower precious metal load than gasoline-powered OEM catalytic converters, making them less valuable. One significant difference is the DOCs lack the precious metal rhodium, which is the most valuable precious metal found in catalytic converters found in gasoline-powered engines.

Edmund Schwenk
(619) 427-8540

Ed has been practicing extractive metallurgy in the precious metals urban mining sector for over 40 years. On October 19, 2019 he was awarded a U.S. Patent for the recycling of PGM’s bound to metallic substrates. This technology is now used in noble6  operations for recovering precious metals that would otherwise have been discarded. Early in the history of the company he created a successful business model that enables small recycling companies to ship their loose autocatalyst direct to North America’s largest smelter allowing them to make the lion’s share of the profits. Recently and after three years of development, he was also responsible for guiding the company to successfully design, build and operate a robotic process line for the recovery of precious metals PT/IR from automotive spark plugs. This line commenced production in December 2020. Ed continues to play an active role in the precious metals industry by providing information and transparency through his company noble6 and their podcast PGM Talks.