A new diesel soot combustion catalysts has been developed at the University of Alicante, which consists of high surface area ceria-praseodymia mixed oxide nanoparticles.
A catalyst active phase has been developed with the following composition
particles size smaller than 9 nm and specific surface areas higher than 90 m2/g. The method used allows obtaining 7 nm particles with 125 m2/g surface area.
Important scientific and technical efforts in order to develop a device for soot removal in diesel engine exhausts, because these carbon nanoparticles are responsible of severe health and environmental negative effects. These devices usually consist of a filter located at in the exhaust pipe, where soot particles are collected, and a catalysts is usually used to lower the soot combustion temperature.
One of the main handicaps of these devices is the poor contact between soot and catalysts particles, which hiders significantly the catalyst performance. Platinum catalysts are the most active ones for this application among those with high enough stability under the demanding conditions of temperature and gas composition that are faced in an exhaust pipe. Alternative catalyst active phases are being investigated in order to lower the prize and improve the activity, and ceria-based oxides are promising candidates.
The synthesis is carried out using a reverse microemulsion and following the several steps:
1. The cerium and praseodymium precursors are dissolved in water.
2. An emulsion is prepared with the previous water solution.
3. Another alkali emulsion is prepared.
4. Both emulsions are mixed.
5. The solid obtained is separated by centrifugation.
6. The solid is calcined at T > 400ºC.
(See fact and figures related to catalyst performance in document attached).
- Better/equal activity than Pt catalysts
- Cheaper prize
Doped ceria nanoparticles loaded into a Diesel Particulate Filter (DPF) have been successfully tested, but the utilization of such nanoparticles as fuel additive has not been explored. Laboratory results lead to think that the doped ceria nanoparticles should also work as fuel additive, but proof-of-concept tests would be required.
This technology is suitable for gas purification in Diesel engine exhausts, like vehicles, stationary power generation engines, etc.