Abstract
The main goal of this project is the development of a catalytic trap, based on a ceramic foam structure carrying a suitable oxidation catalyst for the removal of particulate from Diesel exhausts of passengers cars and light-duty vehicles, so as to fulfil the 2005 European emission standards, whose application is envisaged in 2005. A foam-based catalytic trap should be capable of filtering the particulate and simultaneously promote its catalytic combustion, with acceptable pressure drop and without generation of secondary effects to human health, engine durability and after-treatment system reliability.
This goal will be pursued through 5 major tasks: 1) Filter development; 2) Catalyst development; 3)
Laboratory testing of catalytic traps; 4) Prototype design and preparation; 5) Prototype bench testing. The major objectives of each single task are: 1) development of an open-pore ceramic foam filter of optimised pore size so as to enable good filtration efficiency, good particulate penetration (which favours the catalyst-to-particulate contact) and compatible pressure drop; 2) development of stable catalysts, suitable for igniting Diesel particulate combustion at exhaust temperatures (180-600 °C), lower than the natural self-ignition temperature; deposition of the most promising catalysts on the open-pore ceramic foam substrates for lab testing purposes; 3) lab-scale tests of catalytic foams under stationary conditions, employing as realistic as possible gas feed conditions, so as to select the most promising catalyst-to-foam combination for prototype design purposes; 4) design and production of a prototype for bench testing addressing the critical issues of filter shape and size selection, definition of filter position in the exhaust line, safe and reliable filter canning, etc.; 5) bench tests of the prepared prototypes will be performed on either engines or vehicles according to the European prescriptions in force, so as to verify the fulfilment of the 2005 European emission levels.
The present communication will concern the major achievements attained so far in the just-expired first year of project. Most of the research tasks efforts spent so far were focused on either trap or catalyst development in the attempt to get on the one hand as robust and efficient traps as possible, and, on the other hand, to develop catalysts capable of promoting soot combustion at low temperature (<350°C). Simultaneously, a model for particulate filtration in the above trap has been assembled and validated. On the basis of the critical mass achieved so far, the design and prototyping of the first catalytic traps is expected for the near future.