Evolution mechanism of active sites for selective catalytic reduction of NO_x with NH₃ over Fe-ZSM-5 catalysts doped by Ce/Cu

Abstract

Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_x with NH₃. A variety of characterization techniques (NH₃-SCO, BET, XRD, XPS, UV-Vis, NH₃-TPD, H₂-TPR) were used to explore the changes of the active sites, acid sites and pore structure of the catalyst. It was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic process. The Cu doping into the Fe-ZSM-5 catalyst produced new active species, isolated Cu ions and CuO particles, resulting in the improved low-temperature catalytic activity. However, the NH₃ oxidation was enhanced, and part of the Fe³⁺ active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species, which causes the decrease of the high-temperature activity. The recovery of high-temperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species dispersion. The results provide theoretical support for adjusting the active window of Fe-based SCR catalyst by multi-metal doping.

Keywords

Fe-based zeolite / nitric oxide removal / Cu/Ce modification / active sites / acid sites

References

[1] LianW, RenF, LiuQ, et al.. Evaluation of metal-doped manganese oxide octahedral molecular sieves in catalytic reduction of NO_x from cigarette mainstream smoke [J]. Journal of Central South University, 2012, 19(4): 918-922

[2] WangP, YiJ, GuW, et al.. The influence of xMnyCe/γ-Al₂O₃ on NO_x catalysts on the properties of NO_x storage and reduction over Pt-Ce-Ba/γ-Al₂O₃ catalysts [J]. Chemical Engineering Journal, 2017, 325: 700-707

[3] LiuQ, BianC, MingS, et al.. The opportunities and challenges of iron-zeolite as NH₃-SCR catalyst in purification of vehicle exhaust [J]. Applied Catalysis A: General, 2020, 607: 117865

[4] WangP, JinM, YuD, et al.. Evolution mechanism of N₂O for the selective catalytic reduction of NO_x by NH₃ over Cu-SSZ-13 assisted Fe-BEA catalysts [J]. Catalysis Letters, 2021, 151(11): 3381-3395

[5] YaoJ, ZhongZ. TiO₂ preparation by improved homogeneous precipitation and application in SCR catalyst [J]. Journal of Central South University, 2016, 23(9): 2139-2145

[6] UsuiT, LiuZ, IbeS, et al.. Improve the hydrothermal stability of Cu-SSZ-13 zeolite catalyst by loading a small amount of Ce [J]. ACS Catalysis, 2018, 8(10): 9165-9173

[7] KumarM S, SchwidderM, GrünertW, et al.. Selective reduction of NO with Fe-ZSM-5 catalysts of low Fe content: Part II. Assessing the function of different Fe sites by spectroscopic in situ studies [J]. Journal of Catalysis, 2006, 239(1): 173-186

[8] ShwanS, JanssonJ, KorsgrenJ, et al.. Kinetic modeling of H-BEA and Fe-BEA as NH₃-SCR catalysts—Effect of hydrothermal treatment [J]. Catalysis Today, 2012, 197(1): 24-37

[9] WangP, YuD, ZhangL, et al.. Evolution mechanism of NO_x in NH₃-SCR reaction over Fe-ZSM-5 catalyst: Species-performance relationships [J]. Applied Catalysis A: General, 2020, 607117806

[10] ChenL, JanssensT V W, VennestrømP N R, et al.. A complete multisite reaction mechanism for low-temperature NH₃-SCR over Cu-CHA [J]. ACS Catalysis, 2020, 10(10): 5646-5656

[11] YeQ, WangL, YangR T. Activity, propene poisoning resistance and hydrothermal stability of copper exchanged chabazite-like zeolite catalysts for SCR of NO with ammonia in comparison to Cu/ZSM-5 [J]. Applied Catalysis A: General, 2012, 427–42824-34

[12] WangD, ZhangL, KamasamudramK, et al.. In situ-DRIFTS study of selective catalytic reduction of NO_x by NH₃ over Cu-exchanged SAPO-34 [J]. ACS Catalysis, 2013, 3(5): 871-881

[13] Moreno-GonzálezM, HuesoB, BoronatM, et al.. Ammonia-containing species formed in Cu-chabazite as per in situ EPR, solid-state NMR, and DFT calculations [J]. The Journal of Physical Chemistry Letters, 2015, 6(6): 1011-1017

[14] HamoudH I, ValtchevV, DaturiM. Selective catalytic reduction of NO_x over Cu- and Fe-exchanged zeolites and their mechanical mixture [J]. Applied Catalysis B: Environmental, 2019, 250: 419-428

[15] ZhaoH, LiH, LiX, et al.. The promotion effect of Fe to Cu-SAPO-34 for selective catalytic reduction of NO_x with NH₃ [J]. Catalysis Today, 2017, 297: 84-91

[16] GonzálezJ M, VillaA L. High temperature SCR over Cu-SSZ-13 and Cu-SSZ-13 + Fe-SSZ-13: Activity of Cu²⁺ and [CuOH]¹⁺ sites and the apparent promoting effect of adding Fe into Cu-SSZ-13 catalyst [J]. Catalysis Letters, 2021, 151(10): 3011-3019

[17] JoshiS Y, KumarA, LuoJ, et al.. New insights into the mechanism of NH₃-SCR over Cu- and Fe-zeolite catalyst: Apparent negative activation energy at high temperature and catalyst unit design consequences [J]. Applied Catalysis B: Environmental, 2018, 226: 565-574

[18] MaS, TanH, LiY, et al.. Excellent low-temperature NH₃-SCR NO removal performance and enhanced H₂O resistance by Ce addition over the Cu_0.02Fe_0.2Ce_yTi_1−yO_x (y=0.1, 0.2, 0.3) catalysts [J]. Chemosphere, 2020, 243: 125309

[19] LiJ, JiaL, JinW, et al.. Effects of Ce-doping on the structure and NH₃-SCR activity of Fe/beta catalyst [J]. Rare Metal Materials and Engineering, 2015, 44(7): 1612-1616

[20] FanJ, NingP, WangY, et al.. Significant promoting effect of Ce or La on the hydrothermal stability of Cu-SAPO-34 catalyst for NH₃-SCR reaction [J]. Chemical Engineering Journal, 2019, 369908-919

[21] WangP, YuD, WuG, et al.. NO_x adsorption and desorption of a Mn-incorporated NSR catalyst Pt/Ba/Ce/xMn/γ-Al₂O₃ [J]. Environmental Science and Pollution Research, 2019, 26(27): 27888-27896

[22] ShiX, WangY, ShanY, et al.. Investigation of the common intermediates over Fe-ZSM-5 in NH₃-SCR reaction at low temperature by in situ DRIFTS [J]. Journal of Environmental Sciences, 2020, 94: 32-39

[23] XueH, GuoX, MengT, et al.. Poisoning effect of K with respect to Cu/ZSM-5 used for NO reduction [J]. Colloid and Interface Science Communications, 2021, 44: 100465

[24] YuanQ, ZhangZ, YuN, et al.. Cu-ZSM-5 zeolite supported on SiC monolith with enhanced catalytic activity for NH₃-SCR [J]. Catalysis Communications, 2018, 10823-26

[25] LiW, ChenL, LiuX, et al.. Study on the Cu-ZSM-5 catalyst for SCR system of diesel engine [J]. Advanced Materials Research, 2012, 532–533: 82-86

[26] JouiniH, MejriI, PetittoC, et al.. Characterization and NH₃-SCR reactivity of Cu-Fe-ZSM-5 catalysts prepared by solid state ion exchange: The metal exchange order effect [J]. Microporous and Mesoporous Materials, 2018, 260: 217-226

[27] HanS, ChengJ, YeQ, et al.. Ce doping to Cu-SAPO-18: Enhanced catalytic performance for the NH₃-SCR of NO in simulated diesel exhaust [J]. Microporous and Mesoporous Materials, 2019, 276: 133-146

[28] ZhangT, QinX, PengY, et al.. Effect of Fe precursors on the catalytic activity of Fe/SAPO-34 catalysts for N₂O decomposition [J]. Catalysis Communications, 2019, 128: 105706

[29] HadjiivanovK I, KantchevaM M, KlissurskiD G. IR study of CO adsorption on Cu-ZSM-5 and CuO/SiO₂ catalysts: σ and π components of the Cu⁺-CO bond [J]. J Chem Soc, Faraday Trans, 1996, 92(22): 4595-4600

[30] BinF, SongC, LvG, et al.. Structural characterization and selective catalytic reduction of nitrogen oxides with ammonia: A comparison between Co/ZSM-5 and Co/SBA-15 [J]. The Journal of Physical Chemistry C, 2012, 116(50): 26262-26274

[31] XingX, LiN, ChengJ, et al.. Synergistic effects of Cu species and acidity of Cu-ZSM-5 on catalytic performance for selective catalytic oxidation of n-butylamine [J]. Journal of Environmental Sciences, 2020, 9655-63

[32] DevadasM, KröcherO, ElsenerM, et al.. Characterization and catalytic investigation of Fe-ZSM5 for urea-SCR [J]. Catalysis Today, 2007, 119(1–4): 137-144

[33] GuanB, JiangH, PengX, et al.. Promotional effect and mechanism of the modification of Ce on the enhanced NH₃-SCR efficiency and the low temperature hydrothermal stability over Cu/SAPO-34 catalysts [J]. Applied Catalysis A: General, 2021, 617: 118110

[34] HanS, YeQ, ChengS, et al.. Effect of the hydrothermal aging temperature and Cu/Al ratio on the hydrothermal stability of CuSSZ-13 catalysts for NH₃-SCR [J]. Catalysis Science & Technology, 2017, 7(3): 703-717

[35] MaY, LiZ, ZhaoN, et al.. One-pot synthesis of Cu-Ce co-doped SAPO-5/34 hybrid crystal structure catalysts for NH₃-SCR reaction with SO₂ resistance [J]. Journal of Rare Earths, 2021, 39(10): 1217-1223

[36] QiG, YangR T. Performance and kinetics study for low-temperature SCR of NO with NH₃ over MnO_x-CeO₂ catalyst [J]. Journal of Catalysis, 2003, 217(2): 434-441

[37] XiaY, ZhanW, GuoY, et al.. Fe-beta zeolite for selective catalytic reduction of NO_x with NH₃: Influence of Fe content [J]. Chinese Journal of Catalysis, 2016, 37(12): 2069-2078

[38] ChenZ, LiuL, QuH, et al.. Migration of cations and shell functionalization for Cu-Ce-La/SSZ-13@ZSM-5: The contribution to activity and hydrothermal stability in the selective catalytic reduction reaction [J]. Journal of Catalysis, 2020, 392217-230

[39] SchwidderM, KumarM S, KlementievK, et al.. Selective reduction of NO with Fe-ZSM-5 catalysts of low Fe content: I. Relations between active site structure and catalytic performance [J]. Journal of Catalysis, 2005, 231(2): 314-330

[40] XieS, LiL, JinL, et al.. Low temperature high activity of M (M = Ce, Fe, Co, Ni) doped M-Mn/TiO₂ catalysts for NH₃-SCR and in situ DRIFTS for investigating the reaction mechanism [J]. Applied Surface Science, 2020, 515: 146014

[41] ShanY, SunY, DuJ, et al.. Hydrothermal aging alleviates the inhibition effects of NO₂ on Cu-SSZ-13 for NH₃-SCR [J]. Applied Catalysis B: Environmental, 2020, 275119105

[42] XuH, WangY, CaoY, et al.. Catalytic performance of acidic zirconium-based composite oxides monolithic catalyst on selective catalytic reduction of NO_x with NH₃ [J]. Chemical Engineering Journal, 2014, 24062-73

[43] KiegerS, DelahayG, CoqB, et al.. Selective catalytic reduction of nitric oxide by ammonia over Cu-FAU catalysts in oxygen-rich atmosphere [J]. Journal of Catalysis, 1999, 183(2): 267-280

[44] PengC, YanR, PengH, et al.. One-pot synthesis of layered mesoporous ZSM-5 plus Cu ion-exchange: Enhanced NH₃-SCR performance on Cu-ZSM-5 with hierarchical pore structures [J]. Journal of Hazardous Materials, 2020, 385: 121593

[45] MetkarP S, HaroldM P, BalakotaiahV. Experimental and kinetic modeling study of NH₃-SCR of NO_x on Fe-ZSM-5, Cu-chabazite and combined Fe- and Cu-zeolite monolithic catalysts [J]. Chemical Engineering Science, 2013, 8751-66