It looks like Honda won't be the only Japanese manufacturer producing new clean diesel engines that don't require urea injection to meet Tier II Bin 5 emission standards here in the US. Honda announced the new catalyst technology that they've developed last fall and now Nissan has devised a system of their own.
Nissan has created new catalyst that includes multiple layers. The first layer traps hydrocarbons which react with the catalyst material to produce hydrogen and carbon monoxide. The next stage of the unit causes the H2 and CO to react with the NOx to convert it to nitrogen, carbon dioxide and water. Nissan already announced plans to introduce a diesel version of the Maxima to the US market in 2010 and this could be the technology that makes it fifty state legal.