Search Results

Further developments of those aftertreatment systems, concerning substrates, coatings and reduction agent control, open further potentials of improvements.

Most commonly, ash is mixed with fibers deriving from the gasket on the DPF inlet surface, fibers from the intumescing mat around the DPF and the diesel oxidation catalyst (DOC) upstream the DPF, as well as with newly formed V-O long-prismatic nanocrystals originating from the catalytic coating layer. SEM images reveal the presence of a 130-170 μm thick soot cake on the filter walls of RME20- and RME0-DPF. ...EDX analyses of the layer deposited on the channel walls underneath the soot reveal the following elements: Ca, P, Zn, Mg, S, Na (typical ash elements), V, Ti, W (deriving from the catalytic coating) and Fe, Cu from engine wear. The size distribution of individual soot particles in the soot aggregates (average diameter: 21 nm), together with the nanostructure of soot particles obtained by high resolution transmission electron microscopy (HRTEM) indicate that the RME100 soot is relatively more reactive compared to diesel soot.

The average proportion of NO₂ in exhaust gases of vehicles increases significantly due to the use of oxidation catalysts and catalytic coatings in the exhaust gas systems during the last decades combined with generalization of using low sulfur fuels. ...Diesel oxidation catalysts (DOC) and Pt-containing DPF coatings are widely used to support the regeneration of particle filters, being a source of strongly increased production of NO₂. ...In general it can be stated: - there is a maximum of NO₂/NOx - ratio with Pt-coated catalyst (DOC), or with catalyzed soot filter (CSF), typically when the exhaust gas temperature range is around 350°C; there is even a higher potential for NO₂ formation with higher Pt-content in the coating, - lower NO₂ production appears with higher spatial velocity, higher S content in fuel and with used DOC/DPF and/or when these devices are loaded with soot, - in some cases of semi active regeneration systems (fuel injection upstream of DOC), or with the use of RME conditions with higher NO₂ rates can appear.

Also examined was promoting the regeneration by: throttling, additive (FBC), oxidation catalytic converter upstream of DPF and the catalytic coating of the filter material. The metrics were the particulate matter emission, its composition and the nanoparticles.

Other sources are the metallic additives to the lube oil, metallic additives in the fuel, and debris from the catalytic coatings in the exhaust-gas emission control devices. The formation process results in extremely fine particles, typically smaller than 50 nm.

The main sources are abrasion between piston ring and cylinder, abrasion of bearing, cams and valves, catalyst coatings, metal-organic lubrication oil additives, and fuel additives. While abrasion usually generates particles in the μm range, high concentrations of nanosize metal oxide particles are also observed, probably resulting from nucleation processes during combustion.