The Automotive Exhaust Treatment

Today, all modern passenger cars and trucks are equipped with exhaust gas treatment systems. Different exhaust gas regulations exist in different regions, e.g. EURO in Europe, EPA and CARB in the USA. They all regulate the maximum emissions of carbon monoxide, hydrocarbons and nitrogen oxides (NOx) in vehicle exhausts. Regulations for diesel engines also limit the emission of carbon-particulate matter. Dependent on the engine and vehicle type, the modern treatment of exhaust gas involves a system comprising several different components in a finely tuned system.

The chemical reactions in the exhaust gas treatment are extremely temperature-dependent. However, the exhaust temperatures in running cars or trucks vary. Platinum alloys are used in various components to achieve the reduction of exhaust gases and carbon-particulate matter at the lowest possible temperatures.

Only a combination of reduced untreated engine emissions and the efficient exhaust gas treatment will allow the compliance with future strict emission limits.

The Namos biotemplating technology saves precious metals and as a matter of principle, can be applied to all components containing precious metals.

forward >>

Exhaust Treatment in Diesel Cars

In diesel emissions, carbon-particulate matter must be reduced in addition to carbon monoxide, hydrocarbons and nitrogen oxides. Typical exhaust treatment systems for diesel engines comprise several components (see the second illustration above):

Diesel Oxidation Converter (DOC)

The diesel oxidation converter predominantly catalyses the oxidation of carbon monoxide and hydrocarbons. Although relatively small, the catalytic unit contains quite a bit of precious metal (platinum and in part also palladium).

Catalyzed Soot Filter (CSF)

In CSF filters, soot particles are adsorbed on a porous substrate and oxidized. The oxidation process is either continuous or it is triggered at the set critical load. As always, the presence of platinum reduces the required temperature for the soot oxidation.

NOx Storage Converter (NSC)

This converter mostly catalyzes the reduction of nitrogen oxides to nitrogen. Today’s lean (with high air-fuel ratios) running engines lack sufficient carbon monoxide and hydrocarbons for this reaction. Aside from platinum as catalyst, the NSC converter also contains storage components with high affinity to NOx, such as barium compounds. Intermittent short phases when the engine runs on a rich air-fuel mixture temporarily provide the necessary carbon monoxide and hydrocarbons for the reduction of the now released nitrogen oxides.

Selective Catalytic Reduction (SCR)

An already established method for the reduction of nitrogen oxides is the injection of urea (carbamide). This method is predominantly used for truck engines. This reaction follows the injection of urea in the SCR converter, which does not contain precious metals. The system is more complex than the NOx storage converter. It is therefore doubtful whether SCR will be used for passenger cars.

At this time, the implementation of the Namos biotemplating technology focuses strongly on catalytic converters for diesel engines. The amounts of precious metals are particularly high for these converters and the cost-benefit ratio is therefore tremendous.

forward >>

Precious Metal-Coated Substrates (e.g. Diesel Oxidation Converters)

In diesel oxidation converters (DOCs) as in most other converters, the exhaust gases flow through the narrow channels of a ceramic or metal substrate. The inner channel walls are coated with a layer of porous ceramic (wash coat). The catalytically active precious metal is embedded in this wash coat.

One-Step Coating Procedure

Currently, one-step coating is the most commonly used method. The precious metal is already added when the ceramic coating mixture is prepared. The precious metal and the ceramic coat are applied together in a single step and then tempered (calcinated).

Two-Step Coating Procedure

In special cases, a ceramic coating is first applied to the substrate and calcinated in the absence of precious metal. Only then is the precious metal coating added in a second step by dipping the substrate in a precious metal containing bath.

The Namos biotemplating technology is introduced to the process simply by adding templates when the precious metal is applied. The template addition is possible both in the one-step and the two-step procedure.

forward >>

The Shortcomings of Conventional Coatings – The Namos Biotemplate Solution

With today’s coating methods, only a small fraction of the precious metal in a converter actually functions as a catalyst. This is based on the following facts:

• The working temperatures for catalytic converters in cars are high, high enough to cause the originally small precious metal particles to melt together or sinter.
• Not all locations where precious metal precipitates are created equal. Some precious metal particles are more accessible than others.

It would be advantageous to exclusively deposit precious metal particles where they are the most active as catalysts and most protected from sintering. However, prior technology offers only limited methods to achieve these optimal conditions.

So far, innovations have centered on new and improved procedures, which are unfortunately also increasingly complex and expensive.

Namos Biotemplating

Namos designed a technology without introducing complex processes. Instead, at the heart of the Ramos innovation is the creation of a material with a structural memory. The use of complex biological molecules enables Namos to much better control the placement of catalytic precious metals in converters. So far, we have tested the innovative technology on drill cores under operating conditions identical to those in diesel engines. In this application, we were already able to reduce the platinum use by up to 50 %. Other positive features of the biotemplating solution are:

• The procedure is compatible with existing technologies to deposit precious metals on substrates.
• The innovation works with all substrates used so far.
• Implementing the innovation only requires minimal modifications to the established manufacturing processes for catalytic converters.
• The needed raw materials exist in limitless supply.
• No part of the biological template remains part of the finished catalytic converter. (There will be no negative long-term impact.)

Product Launch >>