This content is not included in your SAE MOBILUS subscription, or you are not logged in.
A Review of Solid Materials as Alternative Ammonia Sources for Lean NOx Reduction with SCR
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 20, 2009 by SAE International in United States
Annotation ability available
The need for improved emissions control in lean exhaust to meet tightening, world-wide NOx emissions standards has led to the development of selective catalytic reduction of NOx with ammonia as a major technology for emissions control. Current systems are being designed to use a solution of urea (32.5 wt %) dissolved in water or Diesel Exhaust Fluid (DEF) as the ammonia source. While DEF or AdBlue® is widely used as a source of ammonia, it has a number of issues at low temperatures, including freezing below −12 °C, solid deposit formation in the exhaust, and difficulties in dosing at exhaust temperatures below 200 °C. Additionally creating a uniform ammonia concentration can be problematic, complicating exhaust packaging and usually requiring a discrete mixer. A number of other materials have been proposed as alternative sources of ammonia that would improve many of these issues; materials such as solid urea, ammonium carbamate, and metal ammine chloride salts allow for the direct injection of ammonia gas into the exhaust.
We have examined the relevant properties of a range of ammonia source materials for their ability to provide ammonia for use in SCR. Important properties, including volumetric efficiency (moles of ammonia/liter), mass efficiency (moles of ammonia/gram), and ammonia release temperatures were evaluated. A number of materials provide an equivalent number of moles of ammonia to AdBlue® in roughly one third the volume or one third the mass. After a careful review of these materials, we have found that ammonium salts (e.g., ammonium carbamate) and metal ammine chlorides (e.g., strontium ammine chloride) offer the most desirable range of properties for use as ammonia source materials. Further issues relating to the use of these materials will be discussed.
CitationFulks, G., Fisher, G., Rahmoeller, K., Wu, M. et al., "A Review of Solid Materials as Alternative Ammonia Sources for Lean NOx Reduction with SCR," SAE Technical Paper 2009-01-0907, 2009, https://doi.org/10.4271/2009-01-0907.
Diesel Exhaust Emission Control, 2009
Number: SP-2254; Published: 2009-04-20
Number: SP-2254; Published: 2009-04-20
- Cavataio, G. Jen, H.-W. Warner, J. R. Girard, J. W. Kim, J. Y. Lambert, C. K. “Enhanced Durability of a Cu/Zeolite Based SCR Catalyst” SAE Paper 2008-01-1025
- Kröcher, O. Elsener, M. Jacob, E. New reducing agents for the low-NOx SCR technology 5th International Exhaust Gas and Particulate Emissions Forum 19–20 February 2008 Ludwigsburg (Germany)
- Rahachandran, B. R. Halpern, A. M. Glendening, E. D. “Kinetics and Mechanism of the Reversible Dissociation of Ammonium Carbamate: Involvement of Carbamic Acid” J. Phys. Chem. A 102 1998 3934 3941
- Sclar C. B. Carrison, L. C. “Phase Composition of Commercial Ammonium Carbonate” Science 14 1963 1205 1207
- Irazoqui H. A. Isla, M. A. “Simulation of a Urea Synthesis Reactor. 2. Reactor Model” Ind. Eng. Chem. Res. 32 1993 2671 2680
- Lepinasse E. Spinner B. 1994 ’Cold production through coupling of solid-gas reactors I: Performance analysis’ Int J Refrig, 17 5 309 322
- Biltz, W. ‘Beiträge zur systematischen Verwandtschaftslehre XXIV. Über das Vermögen 1923
- Vegge, T. Sørensen, R. Z. Klerke, A. Hummelshøj, J. S. Johannessen, T. Nørskov, J. K. Christensen, C. H. “Indirect Hydrogen Storage in Metal Ammines, Part 4: Chemically Bound Hydrogen Storage” Solid-State Hydrogen storage: Materials and Chemistry Walker, G. Woodhead Publishing Limited September 2008
- Johannessen, T. Schmidt, H. Svagin, J. Johansen, J. Oechsle, J. Bradley, R. “Ammonia Storage and Delivery Systems for Automotive Nox Aftertreatment” SAE 2008-01-1027
- Elmoe, T. D. Sorensen, R. Z. Quaade, U. Christensen, C. H. Norskov, J. K. Johannessen, T. “A high-density ammonia storage/delivery system based on Mg(NH 3 ) 6 Cl 2 for SCR–DeNOx in vehicles” Chem. Eng. Sci. 61 2006 2618 2625
- Johannessen, T. Claus, H. Norskov, J. K. Quaade, U. Sorensen, R. Z. “High density storage of ammonia”
- National Inst. of Occupational Safety and Health http://www.cdc.gov/niosh/topics/ammonia
- International Institute of Ammonia Refrigeration https://www.iiar.org/aar/aar_green2.cfm