Topics in Catalysis

, Volume 56, Issue 15–17, pp 1420–1440 | Cite as

Understanding Automotive Exhaust Catalysts Using a Surface Science Approach: Model NOx Storage Materials

  • János Szanyi
  • Cheol Woo Yi
  • Kumudu Mudiyanselage
  • Ja Hun Kwak
Original Paper

Abstract

The structure–reactivity relationships of model BaO-based NOx storage/reduction catalysts were investigated under well controlled experimental conditions using surface science analysis techniques. The reactivity of BaO toward NO2, CO2, and H2O was studied as a function of BaO layer thickness [0 < θBaO < 30 monolayer (ML)], sample temperature, reactant partial pressure, and the nature of the substrate the NOx storage material was deposited onto. Most of the efforts focused on understanding the mechanism of NO2 storage either on pure BaO, or on BaO exposed to CO2 or H2O prior to NO2 exposure. The interaction of NO2 with a pure BaO film results in the initial formation of nitrite/nitrate ion pairs by a cooperative adsorption mechanism predicted by prior theoretical calculations. The nitrites are then further oxidized to nitrates to produce a fully nitrated surface. The mechanism of NO2 uptake on thin BaO films (<4 ML), BaO clusters (<1 ML) and mixed BaO/Al2O3 layers are fundamentally different: in these systems initially nitrites are formed only, and then converted to nitrates at longer NO2 exposure times. These results clarify the contradicting mechanisms presented in prior studies in the literature. After the formation of a nitrate layer the further conversion of the underlying BaO is slow, and strongly depends on both the sample temperature and the NO2 partial pressure. At 300 K sample temperature amorphous Ba(NO3)2 forms that then can be converted to crystalline nitrates at elevated temperatures. The reaction between BaO and H2O is facile, a series of Ba(OH)2 phases form under the temperature and H2O partial pressure regimes studied. Both amorphous and crystalline Ba(OH)2 phases react with NO2, and initially form nitrites only that can be converted to nitrates. The NO2 adsorption capacities of BaO and Ba(OH)2 are identical, i.e., both of these phases can completely be converted to Ba(NO3)2. In contrast, the interaction of CO2 with pure BaO results in the formation of a BaCO3 layer that prevents to complete carbonation of the entire BaO film under the experimental conditions applied in these studies. However, these “carbonated” BaO layers readily react with NO2, and at elevated sample temperature even the carbonate layer is converted to nitrates. The importance of the metal oxide/metal interface in the chemistry on NOx storage-reduction catalysts was studied on BaO(<1 ML)/Pt(111) reverse model catalysts. In comparison to the clean Pt(111), new oxygen adsorption phases were identified on the BaO/Pt(111) surface that can be associated with oxygen atoms strongly adsorbed on Pt atoms at the peripheries of BaO particles. A simple kinetic model developed helped explain the observed thermal desorption results. The role of the oxide/metal interface in the reduction of Ba(NO3)2 was also substantiated in experiments where Ba(NO3)2/O/Pt(111) samples were exposed to CO at elevated sample temperature. The catalytic decomposition of the nitrate phase occurred as soon as metal sites opened up by the removal of interfacial oxygen via CO oxidation from the O/Pt(111) surface. The temperature for catalytic nitrate reduction was found to be significantly lower than the onset temperature of thermal nitrate decomposition.

Keywords

Model NSR catalysts BaO NOx uptake mechanism Co-adsorbates Metal-oxide interface Catalytic nitrate decomposition 

References

  1. 1.
    Granger P, Parvulescu VI (2011) Chem Rev 111:3155CrossRefGoogle Scholar
  2. 2.
    Matsumoto S (2000) CATTECH 4:102CrossRefGoogle Scholar
  3. 3.
    Shelef M (1995) Chem Rev 95:209 (and references therein)CrossRefGoogle Scholar
  4. 4.
    Hoard J, Panov A, SAE Technical Paper 2001-01-3512Google Scholar
  5. 5.
    Tonkyn RG, Yoon S, Barlow SE, Panov A, Kolwaite A, Barmer ML (2000) SAE 1:2869Google Scholar
  6. 6.
    Takahashi N, Shinjoh H, Iijima T, Suzuki T, Yamazaki K, Yokota K, Suzuki H, Miyoshi N, Matsumoto S, Tanizawa T, Tanaka T, Tateishi S, Kasahara K (1996) Catal Today 27:63CrossRefGoogle Scholar
  7. 7.
    Epling WS, Parks JE, Campbell GC, Yezerets A, Currier NW, Campbell LE (2004) Catal Today 96:21 (and references therein)CrossRefGoogle Scholar
  8. 8.
    Stone P, Ishii M, Bowker M (2003) Surf Sci 537:179CrossRefGoogle Scholar
  9. 9.
    Bowker M, Stone P, Smith R, Fourre E, Ishii M, Leeuw NH (1973) Surf Sci 2006:600Google Scholar
  10. 10.
    Bowker M, Cristofolini M, Hall M, Fourre E, Grillo F, McCormack E, Stone P, Ishii M (2007) Top Catal 42:341CrossRefGoogle Scholar
  11. 11.
    Bowker M (2008) Chem Soc Rev 37:2204CrossRefGoogle Scholar
  12. 12.
    Mudiyanselage K, Yi CW, Szanyi J (2009) Langmuir 26:10820CrossRefGoogle Scholar
  13. 13.
    Mudiyanselage K, Yi CW, Szanyi J (2010) J Phys Chem C 114:16955CrossRefGoogle Scholar
  14. 14.
    Mudiyanselage K, Mei D, Yi CW, Weaver JF, Szanyi J (2010) J Phys Chem C 114:20195CrossRefGoogle Scholar
  15. 15.
    Mudiyanselage K, Weaver JF, Szanyi J (2011) J Phys Chem C 115:5903CrossRefGoogle Scholar
  16. 16.
    Mudiyanselage K, Yi CW, Szanyi J (2011) Phys Chem Chem Phys 13:11016CrossRefGoogle Scholar
  17. 17.
    Mudiyanselage K, Szanyi J (2012) Catal Today 181:116CrossRefGoogle Scholar
  18. 18.
    Tsami A, Grillo F, Bowker M, Nix RM (2006) Surf Sci 600:3403CrossRefGoogle Scholar
  19. 19.
    Schmitz P, Baird RJ (2002) J Phys Chem B 106:4172CrossRefGoogle Scholar
  20. 20.
    Ozensoy E, Szanyi J, Peden CHF (2005) J Phys Chem B 109:3431CrossRefGoogle Scholar
  21. 21.
    Ozensoy E, Peden CHF, Szanyi J (2005) J Phys Chem B 109:15977CrossRefGoogle Scholar
  22. 22.
    Ozensoy E, Peden CHF, Szanyi J (2006) J Phys Chem B 110:17001CrossRefGoogle Scholar
  23. 23.
    Ozensoy E, Peden CHF, Szanyi J (2006) J Phys Chem B 110:17009CrossRefGoogle Scholar
  24. 24.
    Ozensoy E, Peden CHF, Szanyi J (2006) J Catal 243:149CrossRefGoogle Scholar
  25. 25.
    Desikusumastuti A, Laurin M, Happel M, Qin Z, Shaikhutdinov S, Libuda J (2008) Catal Lett 121:311CrossRefGoogle Scholar
  26. 26.
    Desikusumastuti A, Staudt T, Grönbeck H, Libuda J (2008) J Catal 255:127CrossRefGoogle Scholar
  27. 27.
    Desikusumastuti A, Happel M, Dumbuya K, Staudt T, Laurin M, Gottfried JM, Steinruck HP, Libuda J (2008) J Phys Chem C 112:6477CrossRefGoogle Scholar
  28. 28.
    Staudt T, Desikusumastuti A, Happel M, Vesselli E, Baraldi A, Gardonio S, Lizzit S, Rohr F, Libuda J (2008) J Phys Chem C 112:9835CrossRefGoogle Scholar
  29. 29.
    Vines F, Desikusumastuti A, Staudt T, Gorling A, Libuda J, Neyman KM (2008) J Phys Chem C 112:16539CrossRefGoogle Scholar
  30. 30.
    Desikusumastuti A, Staudt T, Happel M, Laurin M, Libuda J (2008) J Catal 260:315CrossRefGoogle Scholar
  31. 31.
    Desikusumastuti A, Qin Z, Staudt T, Happel M, Lykhach Y, Laurin M, Shaikhutdinov S, Libuda J (2009) Surf Sci 603:9CrossRefGoogle Scholar
  32. 32.
    Desikusumastuti A, Schernich S, Happel M, Sobota M, Laurin M, Libuda J (2009) ChemCatChem 1:318CrossRefGoogle Scholar
  33. 33.
    Desikusumastuti A, Staudt T, Qin Z, Happel M, Laurin M, Lykhach Y, Shakhutdinov S, Rohr F, Libuda J (2009) Chemphyschem 9:2191CrossRefGoogle Scholar
  34. 34.
    Yi CW, Kwak JH, Peden CHF, Wang C, Szanyi J (2007) J Phys Chem C 111:14942CrossRefGoogle Scholar
  35. 35.
    Yi CW, Kwak JH, Szanyi J (2007) J Phys Chem C 111:15299CrossRefGoogle Scholar
  36. 36.
    Kwak JH, Mei D, Yi CW, Peden CHF, Szanyi J (2009) J Catal 261:17CrossRefGoogle Scholar
  37. 37.
    Yi CW, Szanyi J (2009) J Phys Chem C 113:716CrossRefGoogle Scholar
  38. 38.
    Yi CW, Szanyi J (2009) J Phys Chem C 113:2134CrossRefGoogle Scholar
  39. 39.
    Yi CW, Szanyi J (2009) J Phys Chem C 113:15692CrossRefGoogle Scholar
  40. 40.
    Desikusumastuti A, Qin Z, Happel M, Staudt T, Lykhach Y, Laurin M, Rohr F, Shaikhutdinov S, Libuda J (2009) Phys Chem Chem Phys 11:2514CrossRefGoogle Scholar
  41. 41.
    Schneider WF (2004) J Phys Chem B 108:273CrossRefGoogle Scholar
  42. 42.
    Schneider WF, Hass KC, Miletic M, Gland JL (2002) J Phys Chem B 106:7405CrossRefGoogle Scholar
  43. 43.
    Broqvist P, Grönbeck H, Fridell E, Panas I (2004) Catal Today 96:71CrossRefGoogle Scholar
  44. 44.
    Broqvist P, Panas I, Gronbeck H (2005) J Phys Chem B 109:15410CrossRefGoogle Scholar
  45. 45.
    Szanyi J, Kwak JH, Kim DH, Wang X, Chimentao R, Hanson J, Epling WS, Peden CHF (2007) J Phys Chem C 111:4678CrossRefGoogle Scholar
  46. 46.
    Lutz HD, Eckers W, Schneider G, Haeuseler H (1981) Spectrochim Acta A 37:561CrossRefGoogle Scholar
  47. 47.
    Maneva-Petrova M, Nikolova D (1985) Thermochim Acta 92:287CrossRefGoogle Scholar
  48. 48.
    Cordfunke EHP, Booij AS, Konings RJM, van der Laan RR, Smit Green VM, van Vlaanderen P (1996) Thermochim Acta 273:1CrossRefGoogle Scholar
  49. 49.
    Friedrich A, Kunz M, Suard E (1996) Acta Crystallogr A 57:747CrossRefGoogle Scholar
  50. 50.
    Gland JL (1980) Surf Sci 93:487CrossRefGoogle Scholar
  51. 51.
    Gland JL, Sexton BA (1980) Surf Sci 94:355CrossRefGoogle Scholar
  52. 52.
    Materer N, Starke U, Barbieri A, Doll R, Heinz K, Van Hove MA, Somorjai GA (1995) Surf Sci 325:207CrossRefGoogle Scholar
  53. 53.
    Steininger H, Lehwald S, Ibach H (1982) Surf Sci 123:1CrossRefGoogle Scholar
  54. 54.
    Weaver JF, Chen J, Gerrard AL (2005) Surf Sci 592:83CrossRefGoogle Scholar
  55. 55.
    Gerrard AL, Weaver JF (2005) J Chem Phys 123:224703CrossRefGoogle Scholar
  56. 56.
    James D, Fourre E, Ishii M, Bowker M (2003) Appl Catal B 45:147CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • János Szanyi
    • 1
  • Cheol Woo Yi
    • 1
    • 2
  • Kumudu Mudiyanselage
    • 1
    • 3
  • Ja Hun Kwak
    • 1
    • 4
  1. 1.Institute for Integrated CatalysisPacific Northwest National LaboratoryRichlandUSA
  2. 2.Department of Chemistry and Institute of Basic ScienceSungshin Women’s UniversitySeoulKorea
  3. 3.Chemistry DepartmentBrookhaven National LaboratoryUptonUSA
  4. 4.School of Nano-Bioscience & Chemical EngineeringUNISTUlsanKorea

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