What is GPF and the differences between GPF and TWC

It becomes clear that the new requirements could lead to new, high-performance after-treatment concepts. The latest trends in catalyst development are discussed. Particular attention is paid to solutions for improved cold-start performance. New GPF coatings with high filtration efficiency and catalyst coatings specially developed for gasoline applications for the conversion of NH3 are presented. 

What is DPF and the differences between GPF and TWC ?

The differences between GPF (Gasoline Particulate Filter) and TWC (Three-Way Catalyst) are as follows:

1. Function: GPF is primarily designed to capture and filter particulate matter (PM) emissions from gasoline engines, specifically targeting fine particles in the exhaust gases. On the other hand, TWC is a catalyst used to reduce harmful emissions of three major pollutants: nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (HC).

2. Emission Control: GPF focuses on reducing particulate matter emissions, including soot and other solid particles. It operates by trapping and removing these particles from the exhaust gases. TWC, on the other hand, targets gaseous pollutants, such as NOx, CO, and HC, and facilitates their conversion into less harmful substances through catalytic reactions.

3. Design: GPF is a physical filter typically made of ceramic or metallic materials with a porous structure. It captures and retains particulate matter within its filter medium. TWC consists of a catalyst coating, usually made of precious metals like platinum, palladium, and rhodium, supported on a ceramic or metallic substrate. The catalyst coating facilitates chemical reactions to convert pollutants into less harmful compounds.

4. Application: GPF is specific to gasoline-powered vehicles and is designed to address the particulate emissions associated with gasoline engines, particularly those equipped with gasoline direct injection (GDI) technology. TWC, on the other hand, is used in both gasoline and some hybrid vehicles to control emissions from the combustion of gasoline or gasoline-like fuels.

5. Pollutant Targets: GPF primarily targets particulate matter emissions, including fine particles that contribute to air pollution and adverse health effects. TWC focuses on reducing the levels of NOx, CO, and HC, which are regulated pollutants known for their contribution to smog and harmful effects on air quality.

6. Catalyst Configuration: GPFs typically do not have a catalyst coating, as their main function is particulate filtration. However, some GPFs may incorporate a catalyst coating to enhance the conversion of specific pollutants, such as NH3. TWCs, on the other hand, are specifically designed with catalyst coatings to facilitate the simultaneous reduction of multiple pollutants.

7. Regeneration Process: GPFs require periodic regeneration to burn off the accumulated soot and particulate matter, which is typically achieved through passive or active regeneration methods. TWCs do not require regeneration processes like GPFs since their operation is focused on chemical reactions rather than particulate matter filtration.

8. Emission Standards: Both GPFs and TWCs contribute to meeting emission standards set by regulatory authorities. GPFs help vehicles comply with particulate matter emission limits, while TWCs aid in achieving the required reductions in NOx, CO, and HC emissions.

It's important to note that GPFs and TWCs serve different purposes in controlling emissions from gasoline engines. GPFs target particulate matter, while TWCs focus on the conversion of gaseous pollutants. Their designs, mechanisms, and applications are tailored to address specific emission challenges associated with gasoline engines.

Here are the chemical reaction below

Three-way catalyst (TWC)

In lambda controlled three-way catalysts the following three basic reactions are catalyzed in parallel:

2 NO + 2 CO → N2 + 2 CO2

2 CO + O2 → 2 CO2

2 C2H6 + 7 O2 → 4 CO2 + 6 H2O

Catalyzed Gasoline Particulate Filter (cGPF)

Particulate matter is removed from the exhaust by physical filtration using a honeycomb structure similar to an emission catalyst substrate but with the channels blocked at alternate ends resulting in enhanced filtration efficiency. Also, the catalytic coating provides TWC activity and simultaneously converts CO, HC, and NOx.

2 NO + 2 CO → N2 + 2 CO2

2 CO + O2 → 2 CO2

2 C2H6 + 7 O2 → 4 CO2 + 6 H2O