Search Results

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.

This paper describes the development results of S tolerant Pt-Pd-based Diesel Oxidation Catalyst (DOC) which can be applied for passive DOC application, targeting Euro 4 and India BS4 emission standards with a view of the fact that in India the sulfur content is different in the 13 main cities compared to rest of the country. In order to develop a cost-effective DOC to meet Euro 4 and India BS4 legislation, Pt-Pd-based DOC was studied. Firstly, the effect of Pd used together with Pt in catalytic oxidation performance was studied. DOCs having different Pt to Pd ratios were evaluated in the engine exhaust. The results revealed that CO (Carbon Monoxides) and HC (Hydrocarbons) oxidation activity over Pt-Pd DOC were significantly improved as compared to Pt-only DOCs. It was also revealed that there is an optimum Pt to Pd ratio to give the best light-off performance under conditions tested. Advantage of Pd use with Pt was also confirmed in terms of thermal stability.

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.

A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.

PM (Particulate Matter) emission from Diesel vehicles has been a major concern to countries worldwide due to the negative impact on human health and the environment. With the increasing stringency of emissions regulations, new effective diesel emission control systems are needed for in-use and new diesels vehicles. In order to improve SPM levels in the urban areas of Japan, most local governments are considering new legislation. This legislation will require old in-use diesel vehicles to be retrofitted with a PM reduction device, such as a DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter) or CRT™ (Continuously Regenerating Technology). The CRT™ (Continuously Regenerating Technology) system is an effective device for reduction of PM from in-use diesels. The CRT™ consists of a DOC and a particulate filter which is conventionally a wall-through filter. In the present, more than 30,000 vehicles worldwide are operating with this device.