Catalyst

The most strict regulation in "Euro 6" is for NOx emission standard of diesel cars

In April 2014, Department for Environment, Food and Rural Affairs gave warning against high level air pollution when London was covered with a "White blanket of smog" and "Air pollution warning" was issued by the government in Paris. One of the causes was that diesel engine cars were very popular for its good fuel efficiency in 2000's. Diesel engine cars account for more than 50% of the new vehicle registration and more than 60% in France.
But emission control of the diesel engine cars had been behind compared to it for gasoline engine cars in Europe. Though the regulations had been tightened in order since it was started in 1970's, air pollution had not improved as expected. In September 2014, the tightened regulation "Euro 6" was issued for further control measures.

SCR-Filter system to purify nitrogen oxide (ＮＯｘ)

Technology development of SCR catalyst（※） for diesel engine cars is required to deal with nitrogen oxide(ＮＯｘ) emission control that is getting to be stricter worldwide centering on Europe.
We have established technology to washcoat without increasing airflow resistance of "Diesel Particulate Filter(DPF)" and developed the emission gas purification system, "SCR-Filter system" that integrated SCR catalyst for ＮＯｘ purification and DPF. This SCR-Filter system made it possible to install the emission gas aftertreatment process equipment closer to the engine and to flow higher temperature emission gas. In addition, this system can reduce heat capacity by minimization.
It also realizes catalytic activation at early stage in the low temperature driving area that the emission gas temperature is low right after the engine starting.

SCR catalyst converts nitrogen oxide(ＮＯｘ) into nitrogen molecule(N2) and water(H2O). Decomposition product Ammonia(NH2) is generated by adding urea to exhaust gas and it adsorbs on the catalyst.

Mechanism of purification by SCR-Filter system

Both particulate matters(PM) and nitrogen oxide (NOx) can be purified at the same time by the effect of wash-coated Diesel Particulate Filter(DPF).
The emission gas pass through the DPS wall and the DPF structure gets the soot trapped.
NOx is also purified at the moment the emission gas gets contact with the layer of wash coat on the surface of DPF's walls,

Image of removing "Hydrocarbon", "Carbon Monoxide(CO)", "Particulate Matter(PM) " and "Nitrogen Oxide(ＮＯｘ）"

Catalysts for cars in Europe where compact diesel cars are popular

Since roads in Europe were basically designed for a horse wagon, old towns still have narrow roads so small cars are more convenient. In addition, the amount of CO2 emission per person is regulated in each country and taxed based on emission amount so small cars are more popular.
As we mentioned before, diesel engine cars account for more than 50% of the vehicle registration so the compact diesel car is desired from users.
Diesel Particulate Filter(DPF) is equipped with the diesel engine cars as an essential system to purify soot.
Requirement of compacting space for catalytic converter system by integrating "DPF" and "SCR catalyst" functions is growing in order to use limited car interior effectively.