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Various types of after-treatment system for BS VI Stage 1 are being assessed for the Light Duty Diesel (LDD) segment. For BS VI Stage 2, Real Driving Emission (RDE) assessment will be newly introduced, which will require more robustness in emission control system capability. Although the detailed requirements for India BS VI stage 2 are still being discussed, a reasonable assumption is that similar systems to those being developed for Euro 6d, will work for India BS VI. This paper describes typical system designs for Euro 6d and also reveals newly developed SCRF® (Selective Catalytic Reduction Filter) based systems, which demonstrate excellent RDE emissions. In addition, newly developed Lean NOx Trap (NSC) coatings, which focus on low temperature NOx control used with SCRF® (NSC + SCRF®) also show excellent emission control capability as demonstrated in this case on the ARTEMIS Cycle. These systems have potential as promising LDD solutions for India BS VI stage 2.

The Indian government has announced that India will skip BS V legislation and move to BS VI from 2020. In order to meet this NOx emission standard, most vehicles will need to adopt either NOx Storage Catalyst (NSC) or Selective Catalytic Reduction (SCR). It is shown that these two devices have different NOx reduction temperature windows and different sulfur tolerance. In the LDD application, it is highly important to deal with NOx in the low temperature region directly after a cold start. NSC works in this region with better performance than SCR, but its sulfur tolerance is weaker than SCR. To improve the weakness in low temperature NOx control on SCR, SCRF® which is SCR coated Diesel Particulate Filter (DPF) was developed and it demonstrated an advantage in light-off performance, due to the advantage in temperature conditions, by minimizing heat loss upstream of the SCR device.

Low cost and S(sulphur)-tolerant DOCs (Diesel Oxidation Catalysts) are being demanded in emerging countries such as China and India, where Euro 4 and 5 type emission standards are going to be implemented or are being implemented. However, fuel S content is different in the metros vis-à-vis non metros in many emerging countries. In such a scenario, DOCs need to maintain catalytic performance with high S fuel as well as standard low S fuel. This paper describes the development results of S tolerant Pt-Pd based DOCs. A new washcoat technology (WT D) has been developed for EU 4 passive Pt-Pd DOC applications, in which PGM cost was thrifted by replacing part of Pt by Pd. Vehicle test results after thermal ageing and S poisoning demonstrated that the Pt-Pd DOC (Pt:Pd=4:1) prepared with WT D gave similar tailpipe CO (Carbon monoxide) and HC (Hydrocarbon) emission conversions as a commercially available EU 4 passive Pt-only DOC when 50ppm S diesel fuel was used.

A highly robust Diesel Oxidation Catalyst (DOC) for use with a dual mode combustion system, which makes it possible to switch the combustion between conventional mode and PCI (Premixed Compression Ignition) Combustion mode, was studied. Firstly, commercially available DOCs were tested to confirm current level of emission reduction efficiency for a simulated dual mode combustion system, where CO (Carbon monoxide) was varied from 500 to 5,000 ppm, HC (Hydrocarbon) was varied from 500 to 5,000 ppmC and O2 (Oxygen) was varied from 2 to 15%, respectively. A commercially available Pt based DOC showed good CO and HC light-off performance at 500 ppm of CO and HC at up to 10% O2. However, it did not keep the superior light-off activity when CO and HC were increased to 5,000 ppm and O2 was decreased to 2%. A commercially available Pt-Pd based DOC demonstrated better light-off activity compared to the Pt based DOC at lower CO and HC concentrations.