S.J Jelles

Diesel Particulate Control. Application of an Activated Particulate Trap in Combination with Fuel Additives at an Ultra Low Dose Rate

In laboratory engine tests, a combination of platinum and cerium fuel additives with a platinum activated wall flow monolithic filter has been shown to be especially effective in the control of diesel particulate. Continuous regeneration of a filter can be achieved at temperatures of 600 K using 5 ppm of cerium and 0.5 ppm of platinum in EN590 fuel containing 500 ppm (wt) of sulfur.

Ultra Low Dosage of Platinum and Cerium Fuel Additives in Diesel Particulate Control

The effect of a platinum metal additive on the performance of three commonly used base-metal fuel additives for the catalytic oxidation of diesel particulate was studied. Engine experiments using Corning EX80 filters and oxidation experiments in flow-reactor equipment showed that especially a combination of platinum and cerium additives is very active in the catalytic oxidation of diesel particulates. The additive dose rate can be very low, i.e., about 5 ppm cerium and 0.25 ppm platinum, without loss of effectiveness. NO2 plays a key role in this process. Platinum accumulated on the filter catalyses the oxidation of NO to NO2, whereas cerium catalyses the oxidation of particulate with NO2. Copper and iron do not catalyse the latter reaction. An additional effect of this oxidation mechanism is a substantial NO2 reduction.

Supported liquid phase catalysts: A new approach for catalytic oxidation in diesel exhaust particulate emission control

An exploratory study was carried out with respect to the performance of molten salts as diesel soot oxidation catalyst. The activity of two binary eutectic salts, with a low melting point, was measured and compared with the activity of two very active solid single oxides. Also the influence of NO on the oxidation rate was investigated. It was observed that the molten salt catalysts are highly active compared to the solid single oxide catalysts, probably as a result of the increased contact area due to wetting of the soot by the mobile catalyst. The oxidation rate is strongly increased by the presence of NO in the gas phase.

Influence of Nox on soot combustion with supported molten salt catalysts

Diesel soot is combusted simultaneously by two reactions: combustion with NO2 and combustion with O2 with the aid of a molten salt catalyst. Both reaction pathways should always be considered to avoid misinterpretation of experimental data.

Improved soot oxidation by fuel additives and molten salt catalysts

The removal of soot from dicsel exhaust gas is preferably done catalytically. Fuel additives and supported molten salts are promising catalyst for this application. NO x in the exhaust gas can be used to increase the soot oxidation rate.

Copper catalysis for particulate removal from diesel exhaust gas. Copper fuel additives in combination with copper coatings.

An exploratory study was carried out with respect to the performance of a copper fuel additive in combination with monolithic wall flow filters for the removal of soot from diesel exhaust gas. Cordierite filters, copper coated cordierite filters, and silicon carbide filters were studied. Model experiments have been performed to investigate the influence of contact between soot and catalyst on the oxidation rate. The observation that the effect of a copper coating on the filter performance is marginal compared to the influence of the copper additive is supported by the model experiments. The contact between soot and catalyst is a crucial parameter for the performance of a catalyst. The contact between a copper coating applied to a filter and soot collected on this filter is not sufficient to achieve continuous, complete soot oxidation under realistic diesel engine exhaust conditions.