Recently, a report said Volkswagen had altered diesel engines to beat emissions tests, which immediately caused the great anger of the consumers. The agency reported that some diesel powered vehicles made by Volkswagen and its subsidiaries Audi and Porsche contained software which can lower the emissions during tests; however, during the normal driving, the software has gone. On the discharge gate event, Mullen, the CEO of Volkswagen expressed they had especially tough to come through the past few months. On the road, the emissions of some vehicles can even reach up to 40 times as much NOx—a combination of nitric oxide and nitrogen dioxide—as allowed, which has caused enormous pressure on the environment protection.

 

In the atmosphere, nitrogen dioxide contributes to the formation of ground-level ozone and particulate matter, which create further negative health effects. A recent study estimated that the excess NOx can cause the additional unexpected deaths and damages compared with the regular emissions. In Europe, however, the excess NOx from the altered cars may have little impact, which shows the high NOx emissions have already upset the region, because it has weaker emissions regulations and more diesel powered cars. So the issue of balancing the NOx emissions control with fuel efficiency is a tough nut to crack.

 

In addition, the exhaust of diesel powered vehicles contains a lot of sulfur, which not only causes air pollution, but also causes the poisoning of the denitration catalyst for automotive exhaust gas, and influence the effect of exhaust treatment. Tungsten trioxide denitration catalyst makes the clean diesel technology not a myth. Since tungsten trioxide can improve the sulfidation resistance of the catalyst, it is widely used in the denitration catalyst. In addition, tungsten trioxide can also broaden the operating temperature of the catalyst, and make it suitable for the denitration catalyst under lean burn conditions; therefore, the denitration catalyst which contains tungsten trioxide has very broad prospect in the clean fuel technologies.