Effects of support acidity on the reaction mechanisms of selective catalytic reduction of NO by CH₄ in excess oxygen

Abstract

The reaction mechanisms of selective catalytic reduction (SCR) of nitric oxide (NO) by methane (CH₄) over solid superacid-based catalysts were proposed and testified by DRIFTS studies on transient reaction as well as by kinetic models. Catalysts derived from different supports would lead to different reaction pathways, and the acidity of solid superacid played an important role in determining the reaction mechanisms and the catalytic activities. Higher ratios of BrØnsted acid sites to Lewis acid sites would lead to stronger oxidation of methane and then could facilitate the step of methane activation. Strong BrØnsted acid sites would not necessarily lead to better catalytic performance, however, since the active surface NO_y species and the corresponding reaction routes were determined by the overall acidity strength of the support. The reaction routes where NO₂ moiety was engaged as an important intermediate involved moderate oxidation of methane, the rate of which could determine the overall activity. The reaction involving NO moiety was likely to be determined by the step of reduction of NO. Therefore, to enhance the SCR activity of solid superacid catalysts, reactions between appropriate couples of active NO_y species and activated hydrocarbon intermediates should be realized by modification of the support acidity.

Keywords

selective catalytic reduction (SCR) / nitric oxide (NO) / methane / support acidity / BrØnsted acid sites / NO_y species

References

[1] Li Y, Armor J N. Catalytic reduction of nitrogen oxides with methane in the presence of excess oxygen. Applied Catalysis B: Environmental, 1992, 1(4): 31-40

[2] Kantcheva M, Cayirtepe I. FT-IR spectroscopic investigation of the surface reaction of CH₄ with NOx species adsorbed on Pd/WO₃-ZrO₂ catalyst. Catalysis Letters, 2007, 115(3–4): 148-162

[3] Fokema M D, Ying J Y. The selective catalytic reduction of nitric oxide with methane over nonzeolitic catalysts. Catalysis Reviews—Science and Engineering, 2001, 43(1-2): 1-29

[4] Li Y, Armor J N. Selective catalytic reduction of NOx with methane over metal exchange zeolites. Applied Catalysis B: Environmental, 1993, 2(2-3): 239-256

[5] Zhang X K, Walters A B, Vannice M A. Catalytic reduction of NO by CH₄ over Li-promoted MgO. Journal of Catalysis, 1994, 146(2): 568-578

[6] Feeley J S, Deeba M, Farrauto R J, Beri G, Haynes A. Lean NOx reduction with hydrocarbons over Ga/S-ZrOx and S-GaZr/zeolite catalysts. Applied Catalysis B: Environmental, 1995, 6(1): 79-96

[7] Li N, Wang A Q, Tang J W, Wang X D, Liang D B, Zhang T. NO reduction by CH₄ in the presence of excess O₂ over Co/sulfated zirconia catalysts. Applied Catalysis B: Environmental, 2003, 43(2): 195-201

[8] Li N, Wang A Q, Wang X D, Zheng M Y, Cheng R H, Zhang T. NO reduction by CH₄ in the presence of excess O₂ over Mn/sulfated zirconia catalysts. Applied Catalysis B: Environmental, 2004, 48(4): 259-265

[9] Chin Y H, Pisanu A, Serventi L, Alvarez W E, Resasco D E. NO reduction by CH₄ in the presence of excess O₂ over Pd/sulfated zirconia catalysts. Catalysis Today, 1999, 54(4): 419-429

[10] Cordoba L F, Sachtler W M H, de Correa C M. NO reduction by CH₄ over Pd/Co-sulfated zirconia catalysts. Applied Catalysis B: Environmental, 2005, 56(4): 269-277

[11] Quincoces C E, Guerrero S, Araya P, Gonzalez M G. Effect of water vapor over Pd-Co/SZ catalyst for the NO selective reduction by methane. Catalysis Communications, 2005, 6(1): 75-80

[12] Li N, Wang A Q, Lin L, Wang X D, Ren L L, Zhang T. NO reduction by CH₄ in the presence of excess O₂ over Pd/sulfated alumina catalysts. Applied Catalysis B: Environmental, 2004, 50(1): 1-7

[13] Li N, Wang A Q, Ren W L, Zheng M Y, Wang X D, Zhang T. Pd/sulfated alumina: A new effective catalyst for the selective catalytic reduction of NO with CH₄. Topics in Catalysis, 2004, 30-31(1-4): 103-105

[14] Chin Y H, Alvarez W E, Resasco D E. Sulfated zirconia and tungstated zirconia as effective supports for Pd-based SCR catalysts. Catalysis Today, 2000, 62(2-3): 159-165

[15] Chin Y H, Alvarez W E, Resasco D E. Comparison between methane and propylene as reducing agents in the SCR of NO over Pd supported on tungstated zirconia. Catalysis Today, 2000, 62(4): 291-302

[16] Okumura K, Kusakabe T, Niwa M. Durable and selective activity of Pd loaded on WO₃/ZrO₂ for NO-CH₄-O₂ in the presence of water vapor. Applied Catalysis B: Environmental, 2003, 41(1-2): 137-142

[17] Kantcheva M, Vakkasoglu A S. Cobalt supported on zirconia and sulfated zirconia II. Reactivity of adsorbed NOx compounds toward methane. Journal of Catalysis, 2004, 223(2): 364-371

[18] Djega-Mariadassou G. From three-way to deNOx catalysis: A general model. Catalysis Today, 2004, 90(1-2): 27-34

[19] Yang D, Li J H, Wen M F, Song C L. Selective catalytic reduction of NOx with methane over indium supported on tungstated zirconia. Catalysis Communications, 2007, 8(12): 2243-2247

[20] Yang D, Li J H, Wen M F, Song C L. Selective catalytic reduction of NOx with CH₄ over the In/sulfated TiO₂ catalyst. Catalysis Letters, 2008, 122(1-2): 138-143

[21] Miller J T, Glusker E, Peddi R, Zheng T, Regalbuto J R. The role of acid sites in cobalt zeolite catalysts for selective catalytic reduction of NOx. Catalysis Letters, 1998, 51(1-2): 15-22

[22] Busca G. Spectroscopic characterization of the acid properties of metal oxide catalysts. Catalysis Today, 1998, 41(1-3): 191-206

[23] Reshetenko T V, Avdeeva L B, Khassin A A, Kustova G N, Ushakov V A, Moroz E M, Shmakov A N, Kriventsov V V, Kochubey D I, Pavlyukhin Y T, Chuvilin A L, Ismagilov Z R. Coprecipitated iron-containing catalysts (Fe-Al₂O₃, Fe-Co-Al₂O₃, Fe-Ni-Al₂O₃) for methane decomposition at moderate temperatures: I. Genesis of calcined and reduced catalysts. Applied Catalysis A: General, 2004, 268(1-2): 127-138

[24] Kantcheva M, Kucukkal M U, Suzer S. Spectroscopic investigation of species arising from CO chemisorption on titania-supported manganese. Journal of Catalysis, 2000, 190(1): 144-156

[25] Adelman B J, Beutel T, Lei G D, Sachtler W M H. Mechanistic cause of hydrocarbon specificity over Cu/ZSM-5 and Co/ZSM-5 catalysts in the selective catalytic reduction of NOx. Journal of Catalysis, 1996, 158(1): 327-335

[26] Hadjiivanov K I. Identification of neutral and charged N_xO_y surface species by IR spectroscopy. Catalysis Reviews, 2000, 42(1): 71-144

[27] Wong M S N. Supremolecular templating of mesoporous zirconia-based nanocomposite catalysts. Dissertation for the Doctoral Degree. Boston: Massachusett Institute of Technology, 2000

[28] Arata K. Preparation of superacids by metal oxides for reactions of butanes and pentanes. Applied Catalysis A: General, 1996, 146(1): 3-32

[29] Mantilla A, Tzompantzi F, Ferrat G, López-Ortegac A, Alfaroa S, Gómezb R, Torres M. Oligomerization of isobutene on sulfated titania: Effect of reaction conditions on selectivity. Catalysis Today, 2005, 107-108: 707-712

[30] Halász J, Kónya Z, Fudala Á, Béres A, Kiricsi I. Indium and gallium containing ZSM-5 zeolites: Acidity and catalytic activity in propane transformation. Catalysis Today, 1996, 31(3-4): 293-304

[31] Ansell G P, Diwell A F, Golunski S E, Hayes J W, Rajaram R R, Truex T J, Walker A P. Mechanism of the lean NOx reaction over Cu/ZSM-5. Applied Catalysis B: Environmental, 1993, 2(1): 81-100

[32] Kikuchi E, Ogura M, Terasaki I, Goto Y. Selective reduction of nitric oxide with methane on gallium and indium containing H-ZSM-5 catalysts: Formation of active sites by solid-state ion exchange. Journal of Catalysis, 1996, 161(1): 465-470

[33] Li Y J, Armor J N. Selective catalytic reduction of NO with methane on gallium catalysts. Journal of Catalysis, 1994, 145(1): 1-9

[34] Shelef M, Montreuil C N, Jen H W. NO₂ formation over Cu-ZSM-5 and the selective catalytic reduction of NO. Catalysis Letters, 1994, 26(3-4): 277-284

[35] Beutel T, Adelman B J, Sachtler W M H. FTIR study of the nitrogen isotopic exchange between adsorbed ¹⁵NO₂ complexes and ¹⁴NO over Cu/ZSM-5 and Co/ZSM-5. Applied Catalysis B: Environmental, 1996, 9(1-4): 1-10

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 20677034), the National High-Tech Research and Development (863) Program of China (Grant No. 2006AA060301), and the New Century Excellent Talents in University of China (No. NCET-2005).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg