Not on this engine and here I'm using the 1.5 as an example:
The absorber (1) can store NOx particles at low engine temperature, and then release the NOx particles at high engine temperature.
The deNOx catalytic converter (2) converts the NOx particles in the exhaust gas into nitrogen (N2) and water by means of a urea solution injection.
The deNOx catalytic converter/particle filter assembly (3) traps carbon particles and removes NOx particles as the exhaust gases pass through.
So as you can see a compact design.
Here's a little more detail on the internals for you:
This is the DeNOx absorber
"a" Exhaust gas inlet.
"b" Exhaust gas outlet.
"c" honeycomb ceramic block.
"d" Precious metals.
The carbon monoxide (CO) and the unburnt hydrocarbons (HC) are converted into water and carbon dioxide (CO2) by a chemical reaction.
When the temperature falls below 200°C, the deNOx absorber stores the NOx particles. Once this temperature is exceeded, the NOx particles are released to be processed by the deNOx catalytic converter.
This is the DeNOx catalyser
"a" Exhaust gas inlet.
"b" Exhaust gas outlet.
"e" NOx inlet channels.
"f" Outlet channels for the NOx converted to water and nitrogen (N2).
To convert the NOx to harmless water and nitrogen (N2), a urea solution is injected upstream of the deNOx catalytic converter . On contact with the heat of the exhaust gas, the urea solution is converted to ammonia (NH3) which reacts with the nitrogen oxides and the oxygen contained in excess in the exhaust gas of diesel engines.
This is the DeNOx catalytic converter/particle filter assembly
"a" Exhaust gas inlet.
"b" Exhaust gas outlet.
"g" Inlet channels.
"h" Outlet channels.
The particle emission filter is made up of entry channels closed at their end, which forces the exhaust gas to go through the walls of the channels. These work as a filter and retain the particles.
Essentially consisting of carbon and hydrocarbons, these particles on the particle filter burn in the presence of oxygen at a temperature of 550°C (natural regeneration or with the assistance of post injection).
A fuel injector, installed upstream of the particle emission filter, makes it possible to reach the combustion temperature of the soot by injecting preheated fuel into the exhaust system.
The walls of the particle filter also have a deNOx catalytic converter coating to increase NOx particle removal when the exhaust gas flow and temperature are higher.