Search Results

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.