Capping diesel exhaust with ceramic catalysts
Researchers at Peugeot Citroen, sought to devise both a catalyst and its system that would contribute towards reducing diesel exhaust emissions. To this end, they turned to ceramics with the intention of developing their research in several fundamental areas. They had to develop new forms of filters and new types of catalysts and then design and test them. The catalyst had to be suitable to ignite diesel particulate combustion at 180-600 degrees Celsius. The filter had to allow for excellent particulate filtration, with optimised pore size that allows for favourable particulate-catalyst contact, without which the system would not work. As a result of this research, a stable, open pore ceramic foam trap was successfully devised and tested. The ceramic-based foam allowed for over 80% particulate filtration as well as an acceptable pressure drop within the system. The prototype catalyst system developed was a radial based system that increased the filtration area significantly as compared to the traditional axial types. By increasing the filtration area in this manner, the designers were able to ensure that pressure drop remained at minimal levels. The manufacturing technique used is based on the coating of open cell polyurethane foams by soaking them in a ceramic slurry. Further research will optimise the "polymeric-sponge" process, reducing associated costs, resources and processing times. Currently the developers have a prototype for demonstration but further tests will be conducted to determine the reliability and durability of these ceramic foam diesel filters.
