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Novel exhaust catalyst converter for mobile non-road machinery

Final Report Summary - EXOCAT (Novel exhaust catalyst converter for mobile non-road machinery)

The aim of the EXOCAT project was to develop a novel catalyst converter for diesel non-road mobile machinery, based on non-precious metals and by applying air spray coating technology.

Technical objectives included:
- reduction of NOx, and oxidize CO and HC;
- optimisation of the mixture of oxides;
- improvement of converter performance to Euro III/IV level;
- reduction of the light-off temperature to 100 degrees Celsius.

The work included:
- selection and testing of prospective cobalt oxides;
- design of catalyst precursors with alloyed hydroxides, which need to include a mix of metals (Co, Ni, Cu...);
- selection and optimisation of thermal spraying and its parameters;
- characterisation of the substrate material and coatings by ageing tests on small lab-scale samples;
- prototypes of the catalytic block, with a scaled geometry, Furthermore, vehicle roller bench validation of a full-scale converter with new catalytic block prototype will be executed on a forklift truck.

Results achieved were:
- developed prototype of industrial scale installation for powder precursor production;
- developed method of catalytic coating manufacturing;
- developed industrial scale machine prototype for corrugation of thermally sprayed metal strip;
- developed catalytic elements.

The project was structured into eight Work packages (WPs), as follows:
Work package 1 - Requirements and specification for non-road applications
Work package 2 - Catalyst properties
Work package 3 - Catalyst precursor
Work package 4 - Thermal spraying
Work package 5 - Sprayed catalytic coating characterization and activity
Work package 6 - Catalytic block design
Work package 7 - Catalytic block bench tests
Work package 8 - Dissemination and future exploitation.

The following was done under each work package:

WP1: (Requirements and specifications for non road applications) was completed successfully.
- Detailed scope of the project was developed.
- The functional requirements and specification for catalytic elements for non-road diesel engine exhaust gases refining were defined.

WP2: (Catalyst properties) was completed successfully.
- Evaluation of catalytic activity, selectivity and resistance was done.

WP3 (Catalyst precursor) was completed successfully.
- A model of composite powder precursor (three variants) was developed.
- Three variants of technology (lab-scale) to produce these precursors were developed.
- Prototype of industrial scale installation for powder precursor production was developed and produced.
- Precursor properties after isothermal decomposition were investigated in comparison with hydrotalcite data.
- Tests showed that catalytic properties of precursors, developed by NORTA, are at least 30 % higher, than catalytic properties of hydrotalcite itself.

WP4 (Thermal spraying) was completed successfully.
- Detailed analysis of existing thermal spraying tools and methods was done.
- WP4 was supposed to use HVOF process for effective transportation (without damage in gas stream) of particles of precursor, developed in WP3. The plasma spraying process (NORTA) was supposed to use only for comparison, because this process is well known and can be characterized by considerable damage of precursor particles during their transportation.
- First tests on precursor (model hydrotalcite composition) HVOF spraying gave positive results and showed that the mass of particles should be increased.
- Next tests on second variant of precursor (developed by NORTA in WP3) HVOF spraying showed that the increase of mass for precursor particles is not enough for effective penetration into intermediate layer.
- Taking into account received data, NORTA has developed third variant of precursor with aluminum core (to increase the mass of particle), but according to insufficient technical quality of results of the first two variants it was proposed to use spraying technology available to NORTA. Metallisation has stopped their work in WP4 and their tasks on thermal spraying tools development were overtaken by NORTA.
- NORTA has developed a new technology - soft plasma spraying - which was an attempt to replace HVOF spraying in the project. Soft spraying technology includes two steps:
- soft plasma spraying process;
- restoration of coating surface, damaged during the spraying.

WP5 (Sprayed catalytic coating characterisation) was completed successfully.
- The samples, produced in WP4 according soft spraying technology, were characterised by BET, SEM, X-ray and adhesion tests.
- Spraying (WP4) and testing the samples (WP5) fulfilled by multi-stage iteration, realised in catalytic coating with needed chemical composition (cobalt hydrotalcite), and well formed macro- and microstructure and good adhesion to substrate.

WP6 (Catalytic block design) was completed successfully.
- Design of catalytic block was developed.
- Technology of corrugation and rolling for sprayed (WP4) strip was developed.
- Prototypes of industrial scale installations for corrugation sprayed strip, its rolling and fastening of catalytic block were developed and produced.

WP7 (Catalytic block bench tests) was not totally completed.
About 20 variants of catalytic blocks were produced by NORTA by soft plasma spraying method. These blocks were preliminary tested in KTU on their test bench (to determine the best samples for further testing in CRF).

After preliminary tests (KTU) with low velocity (2,7 l/min) exhaust gases the most prospective variants of catalytic blocks were selected:
- cobalt hydrotalcite (P5-NCT-OG and P5-NCT-BG);
- cobalt hydrotalcite with vanadium (B-75-V-55);
- block including two different catalytic strips; one with catalyst for CO oxidation, other with catalyst for NOx reduction (P6-PFT-OG);
- sirconium based catalyst (P7-1291/1-Cu).

Testing in CRF showed the following:
- maximal NOx conversion is on the level of 6-8 %;
- temperature of 'lighting' in CO oxidation reaction is about 300 degrees Celsius.

According to results received from CRF on catalytic blocks testing it was decided by the consortium to not perform engine steady state tests because of low NOx conversion rates measured during laboratory testing.

WP8 (Dissemination and future exploitation) was completed successfully.
- All foreseen deliverables were successfully delivered to the European Commission.

WP9 (Project and consortium management) was completed successfully.
Based on the work done and the results obtained, the conclusions were:
- tests in CRF showed, that catalytic elements, developed in the project, cannot be applied for automotive applications because of low (6-8 %) NOx reduction capacity;
- from other side, these catalytic elements possibly can be applied for other non-road application, such as diesel locomotive and trains, where the requirements to volume of catalytic elements are not so rigid. It can be proved by KTU test results, where NOx conversion reached 90 %.
- Very important result is that during the project the complex of industrial scale technologies were developed, including production of precursor, soft plasma spraying, technology of mechanical treatment (corrugation, rolling and fastening of catalytic element) and technology of thermal activation.
- The prototypes of industrial scale installation (installation for precursor production, installation for corrugation and for rolling and fastening) are developed.