----- Forwarded by Melanie King/RTP/USEPA/US on 08/05/2010 04:41 PM

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|"Bromberg, Kevin L." <kevin.bromberg@sba.gov>

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|Melanie King/RTP/USEPA/US@EPA, RobertJ Wayland/RTP/USEPA/US@EPA

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| Cc: |

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|"Higgins, Cortney" <Cortney_Higgins@omb.eop.gov>, "Kymn, Christine J."

<Christine_J._Kymn@omb.eop.gov>, "Johnson, Nancy" |

|<Nancy.Johnson@hq.doe.gov>

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|08/05/2010 03:45 PM

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|Catalyst Vendor Graph on NSCR sensitivity to AFR

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More information on NOx NSCR sensitivity, confirms earlier information from

Colorado State University:

Kevin,

As discussed, there is an AFR versus emissions graph at a link from Johnson

Matthey (catalyst vendor) which is similar to the NSCR graph provided a couple

of days ago. It does not include formaldehyde, but shows NOx, hydrocarbon and

CO. It shows “percent reduction” (the previous graph showed actual postcatalyst ppm values) but indicates the same technical issue – i.e., that

reductions of CO and NOx occur over a vary narrow operating window – an AFR

stoichiometric ratio range of about 0.003 in their graph. Also note that the

x-axis covers a narrower range than the previous graph provided so the slope

of the NOx curve is not as steep, but NOx performance is significantly

impacted over an AFR stoichiometric ratio range of about 0.01. You will

recall that the definition of RB engine includes units with an SR of 1.1 or

lower – so the lean side (on the right) goes much beyond the range shown in

this graph. As an aside, this graph indicates similar trends as the graph

provided earlier in the week so it reinforces that point. The linked graph is

an example representation from a control technology vendor, and the levels of

reduction shown on the lean side (e.g., >90% for HC and 99% for CO) should not

be taken literally. I doubt that performance guarantees would be offered at

those levels.

Here is the link:

http://ect.jmcatalysts.com/emission-control-technologies-three-way-catalysts