Effect of C3H6 on selective catalytic reduction of NOx by NH3 over a Cu/zeolite catalyst: A mechanistic study

Abstract The effects of C 3 H 6 on key SCR reactions over a model Cu/beta zeolite catalyst were characterized using step-response method reactor testing. Under standard SCR conditions, C 3 H 6 clearly inhibited the reduction reaction at 200 °C and above. The inhibition was not caused by competitive adsorption between C 3 H 6 and NH 3 , but by surface intermediate species formed during C 3 H 6 oxidation, including acrolein-like and coke species as indicated by in situ DRIFTS. Similar to the standard SCR reaction, C 3 H 6 also had a negative effect on the fast SCR reaction. Spaci-FTIR (spatially resolved capillary-inlet Fourier transform infrared spectroscopy) results indicated that NO 2 was quickly reduced to NO by C 3 H 6 , leading to the occurrence of some standard SCR instead of purely fast SCR. However, C 3 H 6 had a positive effect on NO 2 SCR. The reduction of NO 2 to NO by C 3 H 6 resulted in the occurrence of the fast SCR reaction combined with NO 2 SCR instead of pure NO 2 SCR. The reaction pathway change also decreased N 2 O formation significantly.

[1]  T. Nanba,et al.  Selective catalytic reduction of NOx with NH3 over different copper exchanged zeolites in the presence of decane , 2011 .

[2]  Nathan A. Ottinger,et al.  Deactivation of accelerated engine-aged and field-aged Fe–zeolite SCR catalysts , 2010 .

[3]  R. T. Yang,et al.  Activity, stability and hydrocarbon deactivation of Fe/Beta catalyst for SCR of NO with ammonia , 2009 .

[4]  P. Magnoux,et al.  Organic chemistry of coke formation , 2001 .

[5]  R. T. Yang,et al.  Mechanism of propene poisoning on Fe-ZSM-5 for selective catalytic reduction of NO(x) with ammonia. , 2010, Environmental science & technology.

[6]  J. Lavalley,et al.  In situ FT-IR study of NH3 formation during the reduction of NOx with propane on H/Cu-ZSM-5 in excess oxygen☆ , 1996 .

[7]  M. Makkee,et al.  Coke formation over zeolites and CeO2-zeolites and its influence on selective catalytic reduction of NOx , 2005 .

[8]  M. Elsener,et al.  Urea-SCR: a promising technique to reduce NOx emissions from automotive diesel engines , 2000 .

[9]  P. Claus,et al.  High-throughput study of the effects of inorganic additives and poisons on NH3-SCR catalysts. Part II: Fe–zeolite catalysts , 2010 .

[10]  E. Tronconi,et al.  Ammonia blocking of the “Fast SCR” reactivity over a commercial Fe-zeolite catalyst for Diesel exhaust aftertreatment , 2009 .

[11]  M. López-Muñoz,et al.  Reduction of NOx in C3H6/air mixtures over Cu/Al2O3 catalysts , 1997 .

[12]  Raul F. Lobo,et al.  The ammonia selective catalytic reduction activity of copper-exchanged small-pore zeolites , 2011 .

[13]  Wei Li,et al.  Spatially resolving SCR reactions over a Fe/zeolite catalyst , 2011 .

[14]  A. Obuchi,et al.  High Resistance of Cu–Ferrierite to Coke Formation During NH3-SCR in the Presence of n-Decane , 2009 .

[15]  Jin Ha Lee,et al.  Effect of hydrocarbon slip on NO removal activity of CuZSM5, FeZSM5 and V2O5/TiO2 catalysts by NH3 ☆ , 2011 .

[16]  E. Jobson,et al.  Cu-ZSM-5 zeolite highly active in reduction of NO with decane under water vapor presence: Comparison of decane, propane and propene by in situ FTIR , 2005 .

[17]  E. Tronconi,et al.  The chemistry of the NO/NO2–NH3 “fast” SCR reaction over Fe-ZSM5 investigated by transient reaction analysis , 2008 .

[18]  H. Frei,et al.  Direct Observation of Kinetically Competent Surface Intermediates upon Ethylene Hydroformylation over Rh/Al2O3 under Reaction Conditions by Time-Resolved Fourier Transform Infrared Spectroscopy , 2011 .

[19]  R. T. Yang,et al.  In Situ FT-IR Study of Rh−Al−MCM-41 Catalyst for the Selective Catalytic Reduction of Nitric Oxide with Propylene in the Presence of Excess Oxygen , 1999 .

[20]  M. Daturi,et al.  An operando IR study of the unburnt HC effect on the activity of a commercial automotive catalyst for NH3-SCR , 2011 .

[21]  J. Grunwaldt,et al.  On the mechanism of the SCR reaction on Fe/HBEA zeolite , 2009 .