Wuxi Weifu Environmental Catalysts Co., Ltd.
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DOC Diesel Oxidation Catalyst EU4/5/6 Ceramic/Metal Honeycomb Substrate
DOC (Diesel Oxidation Catalyst)
Used as stand-alone emission control devices, most commercial DOCs were optimized for the reduction of diesel particulate matter emissions. The DOC accomplishes that goal through the removal of the particulate matter’s heavy organic fraction (OF). Certain emission regulations—for instance EU standards for diesel passenger cars—include stringent limits for gaseous HC and CO emissions, which must be reduced over the catalyst as well, often with high efficiencies. DOCs designed for PM/HC/CO control also reduce several unregulated emissions, such as aldehydes and PAHs, as well as the diesel odor.
In their auxiliary catalyst capacity in DPF/SCR systems, DOCs are used primarily as (1) NO2 generating catalysts, and/or (2) “heat-up” catalysts for thermal management of DPF/SCR aftertreatment. An increased NO2/NOx ratio promotes passive DPF regeneration (i.e., oxidation of soot collected in the filter), and can enhance NOx reduction efficiency in SCR catalysts. The role of the heat-up catalyst is to oxidize hydrocarbons—introduced via diesel fuel injection into the exhaust system or post-injection in the engine—to increase the exhaust gas temperature and facilitate active DPF regeneration. If both of these functions are required on a given engine, they are typically combined in one DOC by zone-coating of two DOC formulations optimized for the respective activity.
| Emission Legislation | PM Limit | DOC Application |
|---|---|---|
| Light-Duty Vehicles | ||
| Euro 2 (1996) | PM = 0.08 g/km | DOCs introduced on larger size diesel cars. |
| Euro 3-4 (2000-2005) | PM = 0.05-0.025 g/km | The main aftertreatment strategy, used on most diesel passenger cars and light trucks. |
| Euro 5a (2009.09) | PM = 0.005 g/km | Many cars could meet Euro 5a using a DOC, but DPFs became adopted in some markets (e.g., Germany) for political reasons. |
| Heavy-Duty Engines | ||
| US 1994 | PM = 0.10 g/bhp-hr | DOC introduced on many light and medium heavy-duty engine models, most with mechanical fuel injection systems. DOCs widely used on urban bus engines due to a more stringent PM limit of 0.07-0.05 g/bhp-hr. |
| US 1998 | PM = 0.10 g/bhp-hr | DOC remained common in many light and medium heavy-duty engine models. In some cases, a DOC was no longer required as in-cylinder control was enabled by the replacement of remaining mechanical fuel injection systems with electronically controlled systems required for the lower NOx limits. Urban bus engines continued to rely heavily on DOCs. |
| US 2004 | PM = 0.10 g/bhp-hr | The DOC continued to remain popular for light and medium heavy-duty engine models using EGR to comply with NOx limits. Used for all on-highway engines that did not use external EGR (e.g. Caterpillar ACERT engines). Continued to be used on urban bus engines. |
| Euro IV/V (2005/2008) | PM = 0.02 g/kWh | DOC technology used on some truck engines with EGR (without urea-SCR). |
| Nonroad Tier 4i/Stage IIIB (2011-2012) | PM = 0.02 g/kWh | DOC technology introduced on selected nonroad engine models (mostly those using EGR for NOx control). |
WFEC has developed a series of DOCs to meet China Stage VI or Euro 6, non-road mobile machinery Tier IV, and above emission regulations. The DOCs shows more excellent catalytic performance with improving coat materials and coating process technology.
| Specification of Ceramic DOC | Cell Density (CPSI) | Emission Standard |
| 101.6*123.3 | 300/400/600 | Euro 4/5/6 |
| 101.6*152.4 | 300/400/600 | Euro 4/5/6 |
| 101.6*50 | 300/400/600 | Euro 4/5/6 |
| 101.6*90 | 300/400/600 | Euro 4/5/6 |
| 110*100 | 300/400/600 | Euro 4/5/6 |
| 110*147.3 | 300/400/600 | Euro 4/5/6 |
| 118*100 | 300/400/600 | Euro 4/5/6 |
| 118*127 | 300/400/600 | Euro 4/5/6 |
| 118*152.4 | 300/400/600 | Euro 4/5/6 |
| 118*60 | 300/400/600 | Euro 4/5/6 |
| 118.4*100 | 300/400/600 | Euro 4/5/6 |
| 118.4*127 | 300/400/600 | Euro 4/5/6 |
| 118.4*138 | 300/400/600 | Euro 4/5/6 |
| 118.4*152.4 | 300/400/600 | Euro 4/5/6 |
| 118.4*60 | 300/400/600 | Euro 4/5/6 |
| 118.4*70 | 300/400/600 | Euro 4/5/6 |
| 130*130 | 300/400/600 | Euro 4/5/6 |
| 130*80 | 300/400/600 | Euro 4/5/6 |
| 132*125 | 300/400/600 | Euro 4/5/6 |
| 143.8*101.6 | 300/400/600 | Euro 4/5/6 |
| 143.8*127 | 300/400/600 | Euro 4/5/6 |
| 143.8*148 | 300/400/600 | Euro 4/5/6 |
| 143.8*152.4 | 300/400/600 | Euro 4/5/6 |
| 143.8*76.2 | 300/400/600 | Euro 4/5/6 |
| 150*100 | 300/400/600 | Euro 4/5/6 |
| 151*115 | 300/400/600 | Euro 4/5/6 |
| 158*110 | 300/400/600 | Euro 4/5/6 |
| 158*90 | 300/400/600 | Euro 4/5/6 |
| 165.1*139.7 | 300/400/600 | Euro 4/5/6 |
| 170*100 | 300/400/600 | Euro 4/5/6 |
| 190*100 | 300/400/600 | Euro 4/5/6 |
| 190.5*100 | 300/400/600 | Euro 4/5/6 |
| 190.5*101.6 | 300/400/600 | Euro 4/5/6 |
| 190.5*152.4 | 300/400/600 | Euro 4/5/6 |
| 197*85 | 300/400/600 | Euro 4/5/6 |
| 240*100 | 300/400/600 | Euro 4/5/6 |
| 266.7*101.6 | 300/400/600 | Euro 4/5/6 |
| 266.7*152.4 | 300/400/600 | Euro 4/5/6 |
| 330.2*152.4 | 300/400/600 | Euro 4/5/6 |
| Remark: | Other sizes can be customized. | |
| Specification of Metal DOC | Cell Density (CPSI) | Emission Standard |
| 63.5*100*90 | 200/300 | Euro 4/5/6 |
| 63.5*50*40 | 200/300 | Euro 4/5/6 |
| 80*90*90 | 200/300 | Euro 4/5/6 |
| 89*100*90 | 200/300 | Euro 4/5/6 |
| 101.6*115*100 | 200/300 | Euro 4/5/6 |
| 130*140*130 | 200/300 | Euro 4/5/6 |
| 151*150*140 | 200/300 | Euro 4/5/6 |
| 177.8*114.3*127 | 200/300 | Euro 4/5/6 |
| 184.5*110*100 | 200/300 | Euro 4/5/6 |
| 209.9*110*100 | 200/300 | Euro 4/5/6 |
| 209.9*110*100 | 200/300 | Euro 4/5/6 |
| 221*150*140 | 200/300 | Euro 4/5/6 |
| 235.3*110*100 | 200/300 | Euro 4/5/6 |
| 250*100*90 | 200/300 | Euro 4/5/6 |
| 260.7*110*100 | 200/300 | Euro 4/5/6 |
| 274*160*150 | 200/300 | Euro 4/5/6 |
| 277*160*150 | 200/300 | Euro 4/5/6 |
| 293*160*150 | 200/300 | Euro 4/5/6 |
| 296*200*180 | 200/300 | Euro 4/5/6 |
| 350*100*90 | 200/300 | Euro 4/5/6 |
| 450*100*90 | 200/300 | Euro 4/5/6 |
| Remark: | Other sizes can be customized. | |