Study on the mechanism of NH₃-selective catalytic reduction over CuCe_xZr_{1--<?Pub Caret?>x}/TiO₂

Abstract

Copper--cerium--zirconium catalysts loaded on TiO₂ prepared by a wet impregnation method were investigated for NH₃-selective catalytic reduction (SCR) of NO_x. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy (DRIFT). When NH₃ is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe_0.25Zr_0.75/TiO₂ at high temperature, while Brønsted acid sites are more important than Lewis acid sites at low temperature. For the NH₃+NO+O₂ co-adsorption, NH₃ species occupy most of activity sites on CuCe_0.25Zr_0.75/TiO₂ catalyst, and mainly exist in the forms of NH₄⁺ (at low temperature) and NH₃ coordinated (at high temperature), playing a crucial role in the NH₃-SCR process. Two different reaction routes, the L-H mechanism at low temperature (<200°C) and the E-R mechanism at high temperature (>200°C), are presented for the SCR reaction over CuCe_0.25Zr_0.75/TiO₂ catalyst.

Keywords

CuCe_0.25Zr_0.75/TiO₂ / catalyst / selective catalytic reduction (SCR) / diffuse reflectance infrared transform spectroscopy (DRIFT) / reaction mechanism

References

[1] Johnson T V. Review of diesel emissions and control. International Journal of Engine Research, 2009, 10(5): 275–285

[2] Nakajima F, Hamada I. The state-of-the-art technology of NO_x control. Catalysis Today, 1996, 29(1–4): 109–115

[3] Lietti L, Forzatti P, Bregani F. Steady-state and transient reactivity study of TiO₂-supported V₂O₅–WO₃ De–NO_x catalysts: Relevance of the vanadium–tungsten interaction on the catalytic activity. Industrial & Engineering Chemistry Research, 1996, 35(11): 3884–3892

[4] Casagrande L, Lietti L, Nova I, . SCR of NO by NH₃ over TiO₂-supported V₂O₅–MoO₃ catalysts: reactivity and redox behavior. Applied Catalysis B: Environmental, 1999, 22(1): 63–77

[5] Zhang R, Teoh W Y, Amal R, . Catalytic reduction of NO by CO over Cu/Ce_xZr_1-xO₂ prepared by flame synthesis. Journal of Catalysis, 2010, 272(2): 210–219

[6] Fedeyko J M, Chen B, Chen H Y. Mechanistic study of the low temperature activity of transition metal exchanged zeolite SCR catalysts. Catalysis Today, 2010, 151(3–4): 231–236

[7] Centi G, Nigro C, Perathoner S, . Role of the support and of adsorbed species on the behavior of Cu-based catalysts for NO conversion. Catalysis Today, 1993, 17(1–2): 159–166

[8] Centi G, Perathoner S. Adsorption and reactivity of NO on copper-on-alumina catalysts: II. Adsorbed species and competitive pathways in the reaction of NO with NH₃ and O₂. Journal of Catalysis, 1995, 152(1): 93–102

[9] Komatsu T, Ogawa T, Yashima T. Nitrate species on Cu-ZSM-5 catalyst as an intermediate for the reduction of nitric oxide with ammonia. Journal of Physical Chemistry, 1995, 99(35): 13053–13055

[10] Kwon D W, Nam K B, Hong S C. The role of ceria on the activity and SO₂ resistance of catalysts for the selective catalytic reduction of NO_x by NH₃. Applied Catalysis B: Environmental, 2015, 166–167: 37–44

[11] Xu W, Yu Y, Zhang C, . Selective catalytic reduction of NO by NH₃ over a Ce/TiO₂ catalyst. Catalysis Communications, 2008, 9(6): 1453–1457

[12] Shen Y, Zhu S, Qiu T, . A novel catalyst of CeO₂/Al₂O₃ for selective catalytic reduction of NO by NH₃. Catalysis Communications, 2009, 11(1): 20–23

[13] Chen L, Li J, Ge M, . Enhanced activity of tungsten modified CeO₂/TiO₂ for selective catalytic reduction of NO_x with ammonia. Catalysis Today, 2010, 153(3–4): 77–83

[14] Gao X, Du X, Cui L, . A Ce–Cu–Ti oxide catalyst for the selective catalytic reduction of NO with NH₃. Catalysis Communications, 2010, 12(4): 255–258

[15] Cheng K, Liu J, Zhang T, . Effect of Ce doping of TiO₂ support on NH₃-SCR activity over V₂O₅–WO₃/CeO₂–TiO₂ catalyst. Journal of Environmental Sciences, 2014, 26(10): 2106–2113

[16] Liu K, Liu F, Xie L, . DRIFTS study of a Ce-W mixed oxide catalyst for the selective catalytic reduction of NO_x with NH₃. Catalysis Science & Technology, 2015, 5(4): 2290–2299

[17] Pang L, Fan C, Shao L, . The Ce doping Cu/ZSM-5 as a new superior catalyst to remove NO from diesel engine exhaust. Chemical Engineering Journal, 2014, 253: 394–401

[18] Dou B, Lv G, Wang C, . Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia. Chemical Engineering Journal, 2015, 270: 549–556

[19] Thevenin P O, Alcalde A, Pettersson L J, . Catalytic combustion of methane over cerium-doped palladium catalysts. Journal of Catalysis, 2003, 215(1): 78–86

[20] Bin F, Song C, Lv G, . Selective catalytic reduction of nitric oxide with ammonia over zirconium-doped copper/ZSM-5 catalysts. Applied Catalysis B: Environmental, 2014, 150–151: 532–543

[21] Topsøe N Y. Characterization of the nature of surface sites on vanadia–titania catalysts by FTIR. Journal of Catalysis, 1991, 128(2): 499–511

[22] Topsøe N Y. Mechanism of the selective catalytic reduction of nitric oxide by ammonia elucidated by in situ on-line Fourier transform infrared spectroscopy. Science, 1994, 265(5176): 1217–1219

[23] Topsøe N Y, Topsoe H, Dumesic J A. Vanadia/titania catalysts for selective catalytic reduction (SCR) of nitric-oxide by ammonia: I. Combined temperature-programmed in-situ FTIR and on-line mass-spectroscopy studies. Journal of Catalysis, 1995, 151(1): 226–240

[24] Topsøe N Y, Dumesic J A, Topsoe H. Vanadia–titania catalysts for selective catalytic reduction of nitric-oxide by ammonia: II. Studies of active sites and formulation of catalytic cycles. Journal of Catalysis, 1995, 151(1): 241–252

[25] Chen T, Guan B, Lin H, . In situ DRIFTS study of the mechanism of low temperature selective catalytic reduction over manganese–iron oxides. Chinese Journal of Catalysis, 2014, 35(3): 294–301

[26] Ramis G, Busca G, Bregani F, . Fourier transform-infrared study of the adsorption and coadsorption of nitric oxide, nitrogen dioxide and ammonia on vanadia–titania and mechanism of selective catalytic reduction. Applied Catalysis, 1990, 64: 259–278

[27] Lietti L, Svachula J, Forzatti P, . Surface and catalytic properties of vanadia–titania and tungsta–titania systems in the selective catalytic reduction of nitrogen oxides. Catalysis Today, 1993, 17(1–2): 131–139

[28] Kijlstra W S, Brands D S, Smit H I, . Mechanism of the selective catalytic reduction of NO with NH₃ over MnO_x/Al₂O₃. Journal of Catalysis, 1997, 171(1): 219–230

[29] Qi G, Yang R T. Characterization and FTIR studies of MnO_x–CeO₂ catalyst for low-temperature selective catalytic reduction of NO with NH₃. Journal of Physical Chemistry B, 2004, 108(40): 15738–15747

[30] Pena D A, Uphade B S, Reddy E P, . Identification of surface species on titania-supported manganese, chromium, and copper oxide low-temperature SCR catalysts. Journal of Physical Chemistry B, 2004, 108(28): 9927–9936

[31] Li Q, Gu H, Li P, . In situ IR studies of selective catalytic reduction of NO with NH₃ on Ce–Ti amorphous oxides. Chinese Journal of Catalysis, 2014, 35(8): 1289–1298

[32] Sun X, Gong C, Lv G, . Effect of Ce/Zr molar ratio on the performance of Cu–Ce_x–Zr_1-x/TiO₂ catalyst for selective catalytic reduction of NO_x with NH₃ in diesel exhaust. Materials Research Bulletin, 2014, 60: 341–347

[33] Busca G, Lietti L, Ramis G, . Chemical and mechanistic aspects of the selective catalytic reduction of NO_x by ammonia over oxide catalysts: A review. Applied Catalysis B: Environmental, 1998, 18(1–2): 1–36

[34] Chmielarz L, Kuśtrowski P, Zbroja M, . SCR of NO by NH₃ on alumina or titania pillared montmorillonite modified with Cu or Co: Part II. Temperature programmed studies. Applied Catalysis B: Environmental, 2004, 53(1): 47–61

[35] Pena D A, Uphade B S, Smirniotis P G. TiO₂ supported metal oxide catalysts for low-temperature selective catalytic reduction of NO with NH₃: I. Evaluation and characterization of first row transition metals. Journal of Catalysis, 2004, 221(2): 421–431

[36] Si Z, Weng D, Wu X, . Modifications of CeO₂–ZrO₂ solid solutions by nickel and sulfate as catalysts for NO reduction with ammonia in excess O₂. Catalysis Communications, 2010, 11(13): 1045–1048

[37] Li J, Hao J, Fu L, . The activity and characterization of sol–gel Sn/Al₂O₃ catalyst for selective catalytic reduction of NO_x in the presence of oxygen. Catalysis Today, 2004, 90(3–4): 215–221

[38] Li J, Zhu Y, Ke R, . Improvement of catalytic activity and sulfur-resistance of Ag/TiO₂–Al₂O₃ for NO reduction with propene under lean burn conditions. Applied Catalysis B: Environmental, 2008, 80(3–4): 202–213

[39] Shimizu K I, Satsuma A, Hattori T. Selective catalytic reduction of NO by hydrocarbons on Ga₂O₃/Al₂O₃ catalysts. Applied Catalysis B: Environmental, 1998, 16(4): 319–326

[40] Larrubia M A, Ramis G, Busca G. An FT-IR study of the adsorption of urea and ammonia over V₂O₅–MoO₃–TiO₂ SCR catalysts. Applied Catalysis B: Environmental, 2000, 27(3): L145–L151

[41] Ramis G, Yi L, Busca G. Ammonia activation over catalysts for the selective catalytic reduction of NO_x and the selective catalytic oxidation of NH₃. An FT-IR study. Catalysis Today, 1996, 28(4): 373–380

[42] Yang X, Zhao B, Zhuo Y, . DRIFTS study of ammonia activation over CaO and sulfated CaO for NO reduction by NH₃. Environmental Science & Technology, 2011, 45(3): 1147–1151

[43] Lin C H, Bai H. Surface acidity over vanadia/titania catalyst in the selective catalytic reduction for NO removal - in situ DRIFTS study. Applied Catalysis B: Environmental, 2003, 42(3): 279–287

[44] Centeno M, Carrizosa I, Odriozola J. In situ DRIFTS study of the SCR reaction of NO with NH₃ in the presence of O₂ over lanthanide doped V₂O₅/Al₂O₃ catalysts. Applied Catalysis B: Environmental, 1998, 19(1): 67–73

[45] Xu W, He H, Yu Y. Deactivation of a Ce/TiO₂ catalyst by SO₂ in the selective catalytic reduction of NO by NH₃. Journal of Physical Chemistry C, 2009, 113(11): 4426–4432

[46] Ramis G, Busca G, Lorenzelli V, . Fourier transform infrared study of the adsorption and coadsorption of nitric oxide, nitrogen dioxide and ammonia on TiO₂ anatase. Applied Catalysis, 1990, 64(0): 243–257

[47] Ramis G, Angeles Larrubia M. An FT-IR study of the adsorption and oxidation of N-containing compounds over Fe₂O₃/Al₂O₃ SCR catalysts. Journal of Molecular Catalysis A Chemical, 2004, 215(1–2): 161–167

[48] Chen L, Li J, Ge M. DRIFT study on cerium-tungsten/titania catalyst for selective catalytic reduction of NO_x with NH₃. Environmental Science & Technology, 2010, 44(24): 9590–9596

[49] Lin S D, Gluhoi A C, Nieuwenhuys B E. Ammonia oxidation over Au/MO_x/γ-Al₂O₃-activity, selectivity and FTIR measurements. Catalysis Today, 2004, 90(1–2): 3–14

[50] Wang J, Yan Z, Liu L, . In situ DRIFTS investigation on the SCR of NO with NH₃ over V₂O₅ catalyst supported by activated semi-coke. Applied Surface Science, 2014, 313: 660–669

[51] Hadjiivanov K, Knözinger H. Species formed after NO adsorption and NO+ O₂ co-adsorption on TiO₂: an FTIR spectroscopic study. Physical Chemistry Chemical Physics, 2000, 2(12): 2803–2806

[52] Martínez-Arias A, Soria J, Conesa J C, . NO reaction at surface oxygen vacancies generated in cerium oxide. Journal of the Chemical Society, Faraday Transactions, 1995, 91(11): 1679–1687

[53] Shan W, Liu F, He H, . A superior Ce–W–Ti mixed oxide catalyst for the selective catalytic reduction of NO_x with NH₃. Applied Catalysis B: Environmental, 2012, 115–116: 100–106

[54] Cao F, Su S, Xiang J, . The activity and mechanism study of Fe–Mn–Ce/γ-Al₂O₃ catalyst for low temperature selective catalytic reduction of NO with NH₃. Fuel, 2015, 139: 232–239

[55] Liu F, He H. Selective catalytic reduction of NO with NH₃ over manganese substituted iron titanate catalyst: Reaction mechanism and H₂O/SO₂ inhibition mechanism study. Catalysis Today, 2010, 153(3–4): 70–76

[56] Richter M, Trunschke A, Bentrup U, . Selective catalytic reduction of nitric oxide by ammonia over egg-shell MnO_x/NaY composite catalysts. Journal of Catalysis, 2002, 206(1): 98–113

[57] Salker A V, Weisweiler W. Catalytic behaviour of metal based ZSM-5 catalysts for NO_x reduction with NH₃ in dry and humid conditions. Applied Catalysis A: General, 2000, 203(2): 221–229

[58] Gilardoni F, Weber J, Baiker A. Mechanism of the vanadium oxide-catalyzed selective reduction of NO by NH₃. A quantum chemical modeling. Journal of Physical Chemistry A, 1997, 101(34): 6069–6076

[59] Koebel M, Elsener M, Madia G. Reaction pathways in the selective catalytic reduction process with NO and NO₂ at low temperatures. Industrial & Engineering Chemistry Research, 2001, 40(1): 52–59

[60] Gao X, Liu S, Zhang Y, . Low temperature selective catalytic reduction of NO and NO₂ with NH₃ over activated carbon-supported vanadium oxide catalyst. Catalysis Today, 2011, 175(1): 164–170

[61] Devadas M, Kröcher O, Elsener M, . Influence of NO₂ on the selective catalytic reduction of NO with ammonia over Fe-ZSM5. Applied Catalysis B: Environmental, 2006, 67(3–4): 187–196

[62] Liu F, He H, Zhang C, . Mechanism of the selective catalytic reduction of NO_x with NH₃ over environmental-friendly iron titanate catalyst. Catalysis Today, 2011, 175(1): 18–25

[63] Eigenmann F, Maciejewski M, Baiker A. Selective reduction of NO by NH₃ over manganese–cerium mixed oxides: Relation between adsorption, redox and catalytic behavior. Applied Catalysis B: Environmental, 2006, 62(3–4): 311–318

Acknowledgements

This study was supported by the National Natural Science Foundation of China (Grant No. 51176139) and the Natural Science Foundation of Tianjin (12JCQNJC05700).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg