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Catalystic traps for diesel particulate control

Objective



- Task1: An oriented engineering model for the prediction of diesel foam filter operation was developed. Back pressure, filtration, particulate accumulation, heat transfer and thermal regeneration models were developed in this study. To validate the models for filter development, experiments were adapted and optimised to validate filtration efficiency and pressure drop models. The second part of the Filter Development study concerns the foam trap structural optimisation. A definition of the composition, an optimisation of the slurry, mechanical tests, an optimisation of the open-pore structure were the different steps to the new recipe definition. Alumina and Mullite toughened by zirconia ceramic foams, with fine porosity, were the best compromise between mechanical and thermal properties;
- Task 2: Catalysts investigated were pure metavanadates, binary eutectic mixtures, pure pyrovanadates, and ternary eutectic mixtures. Oxidation and ageing tests, and chemical stability of the catalyst deposit on ceramic foam allowed the partners to select one oxide mixture catalyst as the best compromise for its catalytic activity and its eutectic melting temperature. The deposition procedure was optimised to prepare a number of different shape ceramic foam impregnated with the defined catalyst;
- Task 3: Investigation of catalytic foam samples at a lab scale by employing synthetic gas and particulate mixtures as feed gases was carried out. Some engine preliminary tests were performed too. The activity of the studied catalysts, their stabilities, the catalytic foam thermal and mechanical behaviour and its filtration efficiency were assessed. Different configuration of prototypes were considered;
- Task 4: After investigation on radial flow design filters, catalysed and un-catalysed, on steady state operating points, during soot accumulation and balanced tests, a New filter prototype was designed, prepared and qualify;
- Task 5: The New prototype was tested on engine bench during soot loading and soot regeneration. Hot shake tests were also carried out to check the ability of the New prototype to resist to vibration, temperature and acceleration. The performance of the developed CATATRAP prototype on a up-to-date common rail Diesel engine showed promising results (low pressure drop, acceptable filtration efficiency, high particulate storage capacity, relatively low regeneration temperature). Vehicle tests were done to characterize the best prototype selected during the project, to test its efficiency in soot filtration and regeneration. Some experiments were defined to validate or to measure the efficiency of particulate filter according to the European certification for sequential system as DPF to assess a filter efficiency and a catalytic activity of the system. The calculation of the Standard Particulate Emission of the system leaded to 0.027g/km. The filtration efficiency of the CATATRAP system is between 25% and 40%. It can be foreseen that the filtration efficiency can improved by an accurate optimisation of the filter (volume, length, porosity). The back pressure is acceptable in the exhaust line and the prototype is robust as it was demonstrated on road and on engine bench. The performance of regeneration can be optimised by tuning the soot load according to the foam volume.
Objectives and content
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
as opposed to other potential solutions (e.g. use of fuel
additives and a non-catalytic trap).
This goal will be pursued through 6 major tasks:
Filter development;
Catalyst development;
Laboratory testing of catalytic traps;
Prototype design and preparation;
Prototype bench testing;
Project co-ordination and management.
The major objectives of each single task are:
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;
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;
Lab-scale tests of catalytic foams under stationary
conditions, employing as realistic as possible gas feed
conditions, so as to select the most promising catalystto-foam combination for prototype design purposes;
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
tailpipe, safe and reliable filter canning, etc.;
Bench tests of the prepared prototypes will be
performed on either engines or vehicles according to the
European prescriptions in force, so as to check whether
the 2005 European emission levels can actually be
accomplished.
A European industrial partner according to its
expertise will lead each task, particularly:
A ceramic filter manufacturer;
A catalyst manufacturer (exploiter of the technology);
A car manufacturer (end-user);
An exhaust system manufacturer;
Another car manufacturer (end-user), acting also as
project co-ordinator. Three universities are involved in
catalyst development and deposition as well as in
catalytic trap modelling and design.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

GIE PSA Peugeot Citroën
Address
Route De Gisy
78140 Vélizy-villacoublay
France

Participants (7)

ARISTOTLE UNIVERSITY OF THESSALONIKI
Greece
Address
University Campus, Egntia Str.
54006 Thessaloniki
CENTRO RICERCHE FIAT S.C.P.A.
Italy
Address
Strada Torino 50
10043 Orbassano
CERAPLAST SA
France
Address
64-66,Rue Paul Claudel 64-66
87000 Limoges
Equipements et Composants pour l'Industrie Automobile
France
Address
Bois Sur Prés
25550 Bavans
JOHNSON MATTHEY PLC (TRADING AS SYNETIX)
United Kingdom
Address
Orchard Road
SG8 5HE Royston,herts
POLITECNICO DI TORINO
Italy
Address
Corso Duca Degli Abruzzi 24
10129 Torino (Turin)
Technische Universiteit Delft
Netherlands
Address
136,Julianalaan
2628 BL Delft