Effect of Unburned Methyl Esters on the NOx Conversion of Fe-Zeolite SCR Catalyst

Aaron Williams, Matt Ratcliff, Dan Pedersen, Robert Mccormick, Giovanni Cavataio, Justin Ura

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations


Engine and flow reactor experiments were conducted to determine the impact of biodiesel relative to ultra-low- sulfur diesel (ULSD) on inhibition of the selective catalytic reduction (SCR) reaction over an Fe-zeolite catalyst. Fe-zeolite SCR catalysts have the ability to adsorb and store unburned hydrocarbons (HC) at temperatures below 300°C. These stored HCs inhibit or block NOx-ammonia reaction sites at low temperatures. Although biodiesel is not a hydrocarbon, similar effects are anticipated for unburned biodiesel and its organic combustion products. Flow reactor experiments indicate that in the absence of exposure to HC or B100, NOx conversion begins at between 100° and 200°C. When exposure to unburned fuel occurs at higher temperatures (250°-400°C), the catalyst is able to adsorb a greater mass of biodiesel than of ULSD. Experiments show that when the catalyst is masked with ULSD, NOx conversion is inhibited until it is heated to 400°C. However, when masked with biodiesel, NOx conversion is observed to begin at temperatures as low as 200°C. Engine test results also show low-temperature recovery from HC storage. Engine tests indicate that, overall, the SCR system has a faster recovery from HC masking with biodiesel. This is at least partially due to a reduction in exhaust HCs, and thus total HC exposure with biodiesel.

Original languageAmerican English
Pages (from-to)273-282
Number of pages10
JournalSAE International Journal of Fuels and Lubricants
Issue number2
StatePublished - 2010
EventSAE 2009 Powertrains Fuels and Lubricants Meeting, FFL 2009 - San Antonio, TX, United States
Duration: 2 Nov 20092 Nov 2009

NREL Publication Number

  • NREL/JA-540-46503


  • biofuels


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