Abstract
The selective catalytic reduction (SCR) rate of NO with N-containing reducing agents can be enhanced considerably by converting part of NO into NO2. The enhanced reaction rate is more pronounced even at lower temperatures by using an equimolar mixture of NO and NO2 (fast SCR reaction). The oxidation characteristics of NO over catalyst Pt/TiO2 have been determined in a fixed bed reactor (8 mm-ID) with different concentrations of oxygen, nitric oxide and nitrogen dioxide in the presence of 8% water. The conversion of NO to NO2 increases with increasing oxygen (O2) concentration from 3 to 12%, but it levels off at higher O2 concentrations. The NO conversion to NO2 decreases with increasing NO concentration and it also decreases by an addition of NO2 in the feed stream. Therefore, the oxidation of NO over Pt/TiO2 catalyst could be auto-inhibited by the reaction product of NO2. The effects of CO and SO2 on NO oxidation characteristics have also been determined. In fact, the presence of SO2 significantly suppresses oxidation of NO but due to the less stability of sulfate on anatase structure in TiO2, it becomes less significant. On the other hand, the presence of CO increases NO oxidation significantly due to the auto-inhibition effect by CO. Moreover, the effect of SO2/CO on NO oxidation has also been determined and it was observed that NO oxidation decreases with the increase in SO2/CO ratio.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.References
Alavi A, Hu P, Deutsch T, Silvestrelli PL, Hutter J (1998) CO oxidation on Pt(111): an abinitio density functional theory study. Phys Rev Lett 80:3650–3653
Atkins PW (1994) Physical chemistry, 5th edn. Oxford University Press, Oxford
Bartram ME, Koel BE, Carter EA (1989) Electronic effects of surface oxygen on the bonding of NO to Pt(111). Surf Sci 219:467–489
Baulch DL, Drysdale DD, Horne DG (1973) Evaluated kinetic data for high temperature reactions: homogeneous gas phase reactions of the H2–N2–O2, system Butterworths. London 2:285–300
Bourges P, Lunati S, Mabilon G (1997) Proceedings of the fourth international congress on catalysis and automotive pollution control, vol. 1, p 81
Burch R, Watling TC (1997) Kinetics and mechanism of the reduction of NO by C3H8 over Pt/Al2O3 under lean burn condition. J Catal 169:45–54
Busca G, Lietti L, Ramis G, Berti F (1998) Chemical and mechanistic aspects of the selective catalytic reduction of NO x by ammonia over oxide catalysts: a review. Appl Catal B: Environ 18:1–36
Campbell CT, Ertl G, Segner J (1982) A molecular beam study on the interaction of NO with a Pt(111) surface. Surf Sci 115:309–322
Cullity BD (1978) Elements of X-ray diffraction, 2nd edn. Addison-Wesley Publishing Company Inc, Reading
Dawody J, Skoglundh M, Fridell E (2004) The effect of metal oxide additives (WO3, MoO3, V2O5, Ga2O3) on the oxidation of NO and SO2 over Pt/Al2O3 and Pt/BaO/Al2O3 catalysts. J Mol Catal A: Chem 209:215–225
Despres J, Elsener M, Koebel M, Kröcher O, Schnyder B, Wokaun A (2004) Catalytic oxidation of nitrogen monoxide over Pt/SiO2. Appl Catal B: Environ 50:73–82
Efthimiadis EA, Christoforou SC, Nikolopoulos AA, Vasalos IA (1998) Selective catalytic reduction of NO with C3H8 over Rh/alumina in the presence and absence of SO2 in the feed. Appl Catal B: Environ 22:91–106
Irfan MF, Goo JH, Kim SD, Hong SC (2007) Effect of CO on NO oxidation over platinum based catalysts for hybrid fast SCR process. Chemoshpere 66:54–59
Koebel M, Elsener M, Kleemann M (2000) Urea-SCR: a promising technique to reduce NO x emissions from automotive diesel engines. Catal Today 59:335–345
Koebel M, Madia G, Elsener M (2002) Selective catalytic reduction of NO and NO2 at low temperatures. Catal Today 73:239–247
Madia G, Koebel M, Elsener M, Wokaun A (2002) The effect of an oxidation precatalyst on the NO x reduction by ammonia SCR. Ind Eng Chem Res 41:3512–3517
Oh SH, Fisher GB, Carpenter JE, Goodman DW (1986) Comparative kinetic studies of CO—O2 and CO—NO reactions over single crystal and supported rhodium catalysts. J Catal 100:360–376
Oi-Uchisawa J, Obuchi A, Enomoto R, Liu S, Nanba T, Kushiyama S (2000) Catalytic performance of Pt supported on various metal oxides in the oxidation of carbon black. Appl Catal B: Environ 26:17–24
Olsson L, Fridell E (2002) The influence of Pt oxide formation and Pt dispersion on the reactions NO2 ↔ NO + ½O2 over Pt/Al2O3 and Pt/BaO/Al2O3. J Catal 210:340–353
Olsson L, Westerberg B, Persson H, Fridell E, Skoglundh M, Andersson B (1999) A kinetic study of oxygen adsorption/desorption and NO oxidation over Pt/Al2O3 catalysts. J Phys Chem B 103:10433–10439
Segner J, Vielhaber W, Ertl G (1982) Isr J Chem 22:375
Treacy JC, Daniels F (1955) Kinetic study of the oxidation of nitric oxide with oxygen in the pressure range 1 to 20 mm. J Am Chem Soc 57:2033–2036
Tsukahara H, Ishida T, Mayumi M (1999) Gas-Phase oxidation of nitric oxide: chemical kinetics and rate constant. Nitric Oxide: Biol Chem 3:191–198
Xue E, Seshan K, Ross JRH (1996) Roles of supports, Pt loading and Pt dispersion in the oxidation of NO to NO2 and of SO2 to SO3. Appl Catal B: Environ 11:65–79
Acknowledgments
The authors would like to thank for a grant-in-aid of research to Dr. S. D. Kim from the Korea Energy Management Corporation (KEMCO) and Korea Power Engineering Company (KOPEC). Also, this work is partly supported by the Brain Korea 21 project.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Irfan, M.F., Goo, J.H. & Kim, S.D. Effects of NO, NO2, CO and SO2 on NO oxidation over Pt/TiO2 for hybrid fast SCR process. Environmentalist 31, 4–10 (2011). https://doi.org/10.1007/s10669-010-9282-9
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10669-010-9282-9