NO reduction by carbon-based gases based on coal gasification fractions: NO reduction intermediate identification and kinetic analysis

Abstract

Combining pulverized coal gasifiers with cement kiln production is promising for application in low-cost and efficient NO reduction. This paper presents a pulverized coal gasifier catalytic denitration technique and investigates the homogeneous reduction (by CO and CH₄) and heterogeneous catalytic reduction (by coke, CaO, MgO, and Fe₂O₃) of NO. A combination of Chemkin simulations and fixed-bed experiments is used to elucidate the reaction pathways and key intermediates of NO reduction by carbon-based gases. In addition, the activation energies for different catalyst combinations were analyzed via reaction kinetics. The results demonstrate that the presence of small amounts of O₂ inhibits NO reduction by CO but promotes NO reduction by CH₄. The NCO• radical is essential for the NO reduction process, and the generation of this radical depends on the CH₄ cleavage intermediate and O• radical. CaO and Fe₂O₃ exhibit more significant catalytic effects on NO reduction by carbon-based gases than the other catalysts tested. The presence of a small amount of O₂ in the reacting gas mixtures facilitates the NO reduction reaction. The activation energy is reduced to 1.02 kJ/mol, and the NO conversion reaches 99.80% when the catalyst is C + CaO + MgO + Fe₂O₃ and the gas composition is CO + CH₄ + O₂. This work provides theoretical support and data recommendations for the use of pulverized coal gasifiers for the denitrification of cement kilns.

Graphical abstract

Keywords

Carbon-based gas / Catalytic denitration / Coke / Kinetic analysis / Reaction mechanism

Highlight

	● The influencing factors of denitration of carbon-based gases were evaluated.
	● The kinetics of catalytic reactions of Coke, CaO, MgO and Fe2O3 were investigated.
	● The NCO• radical was essential for the NO reduction process.
	● Mixtures of alkaline metal oxides may have a synergistic effect on NO reduction.

References

[1] Allen D, Hayhurst A. (2015). The effect of CaO on emissions of nitric oxide from a fluidised bed combustor. Fuel, 158: 898–907

[2] Alzueta M, Glarborg P, Dam-Johansen K. (1997). Low temperature interactions between hydrocarbons and nitric oxide: an experimental study. Combustion and Flame, 109(1−2): 25–36

[3] Atakan B, Kocis D, Wolfrum J, Nelson P. (1992). Direct investigations of the kinetics of the reactions of CN radicals with n atoms and 3CH₂ radicals with NO. Symposium (International) On Combustion, 24(1): 691–699

[4] Brackmann R, Toniolo F, Schmal M. (2016). Synthesis and characterization of Fe-doped CeO₂ for application in the NO selective catalytic reduction by CO. Topics in Catalysis, 59(19−20): 1772–1786

[5] Cai J, Wu H, Ren Q, Lin L, Zhou T, Lyu Q. (2020). Innovative NO_x reduction from cement kiln and pilot-scale experimental verification. Fuel Processing Technology, 199: 106306

[6] Cao Y, Ma Q, Chu B, He H. (2023). Homogeneous and heterogeneous photolysis of nitrate in the atmosphere: state of the science, current research needs, and future prospects. Frontiers of Environmental Science & Engineering, 17(4): 48

[7] Chai S, Li Y, Zhang W, Wang Y, Yang L, Fan X, Chu L. (2022). Effect of Mn-doped CaO on no reduction by CO in carbonation stage of calcium looping: a density functional theory study. Journal of Environmental Chemical Engineering, 10(1): 106987

[8] da Silva M, Schmal M. (2003). Reduction of NO by CO on Pt-MoO₃/γ-Al₂O₃ catalysts. Catalysis Today, 85(1): 31–37

[9] Dam-Johansen K, Hansen P F B, Rasmussen S. (1995). Catalytic reduction of nitric oxide by carbon monoxide over calcined limestone: reversible deactivation in the presence of carbon dioxide. Applied Catalysis B: Environmental, 5(4): 283–304

[10] Fan W, Zhu T, Sun Y, Lv D. (2014). Effects of gas compositions on NO_x reduction by selective non-catalytic reduction with ammonia in a simulated cement precalciner atmosphere. Chemosphere, 113: 182–187

[11] Faravelli T, Frassoldati A, Ranzi E. (2003). Kinetic modeling of the interactions between NO and hydrocarbons in the oxidation of hydrocarbons at low temperatures. Combustion and Flame, 132(1−2): 188–207

[12] Fu S, Song Q, Yao Q. (2015). Study on the catalysis of CaCO₃ in the SNCR de-NO_x process for cement kilns. Chemical Engineering Journal, 262: 9–17

[13] Fu S, Song Q, Yao Q. (2016). Mechanism study on the adsorption and reactions of NH₃, NO, and O₂ on the CaO surface in the SNCR de-NO_x process. Chemical Engineering Journal, 285: 137–143

[14] Geng P, Zhang Y, Liu Z, Liao L, Liu R, Zheng J. (2019). Further insights into the effect of the mass transfer limitations on the reaction order of the char-CO₂ reaction. Thermochimica Acta, 680: 178349

[15] Glarborg P, Kristensen P, Dam-Johansen K, Alzueta M, Millera A, Bilbao R. (2000). Nitric oxide reduction by non-hydrocarbon fuels. Implications for reburning with gasification gases. Energy & Fuels, 14(4): 828–838

[16] Gong Z, Wu W, Zhao Z, Li B. (2018). Combination of catalytic combustion and catalytic denitration on semi-coke with Fe₂O₃ and CeO₂. Catalysis Today, 318: 59–65

[17] HanHChenY YuFLiJ LiuSWangB (2013). Simulation investigation of NO reduction by CO in sintering process. Advanced Materials Research, 781–784: 2590–2593

[18] Harrath K, Boughdiri S. (2018). High catalytic activity of Ti-porphyrin for NO reduction by CO: a first-principles study. Research on Chemical Intermediates, 44(2): 957–969

[19] Hu F, Li P, Li W, Ding C, Guo J, Liu Z. (2021). Experimental and kinetic study of NO-reburning by syngas under high CO₂ concentration in a jet stirred reactor. Fuel, 304: 121403

[20] Huang F, Hu W, Chen J, Wu Y, Qu P, Yuan S, Zhong L, Chen Y. (2018). Insight into enhancement of NO reduction with methane by multifunctional catalysis over a mixture of Ce/HZSM-5 and CoO_x in excess of oxygen. Industrial & Engineering Chemistry Research, 57(40): 13312–13317

[21] Ju T, Lei M, Guo G, Xi J, Zhang Y, Xu Y, Lou Q. (2023). A new prediction method of industrial atmospheric pollutant emission intensity based on pollutant emission standard quantification. Frontiers of Environmental Science & Engineering, 17(1): 8

[22] Lecomte F, Dagaut P, Chevailler S, Cathonnet M. (2000). No-reduction by ethane in a JSR at atmospheric pressure: experimental and kinetic modeling. Combustion Science and Technology, 150(1−6): 181–203

[23] Lee G, Shon B, Yoo J, Jung J, Oh K. (2008). The influence of mixing between NH₃ and NO for a de-NO_x reaction in the SNCR process. Journal of Industrial and Engineering Chemistry, 14(4): 457–467

[24] Lee K, Choi B, Lee C, Oh K. (2020). Effects of SiO₂/Al₂O₃ ratio, reaction atmosphere and metal additive on de-NO_x performance of HC-SCR over Cu-based ZSM-5. Journal of Industrial and Engineering Chemistry, 90: 132–144

[25] Li J, Luo G, Chu Y, Wei F. (2012a). Experimental and modeling analysis of NO reduction by CO for a FCC regeneration process. Chemical Engineering Journal, 184: 168–175

[26] Li J, Wang S, Zhou L, Luo G, Wei F. (2014a). NO reduction by CO over a Fe-based catalyst in FCC regenerator conditions. Chemical Engineering Journal, 255: 126–133

[27] Li N, Wang Y, Cui S, Jin X. (2020a). Experimental and kinetic investigation on NO reduction by rice husk char and catalytically with CO. Applied Sciences, 10(19): 6715

[28] Li P, Li W, Wang K, Hu F, Ding C, Guo J, Liu Z. (2020b). Experiments and kinetic modeling of NO reburning by CH₄ under high CO₂ concentration in a jet-stirred reactor. Fuel, 270: 117476

[29] Li S, Wei X, Guo X. (2012b). Effect of H₂O vapor on NO reduction by CO: experimental and kinetic modeling study. Energy & Fuels, 26(7): 4277–4283

[30] Li S, Yu J, Wei X, Guo X, Chen Y. (2014b). Catalytic reduction of nitric oxide by carbon monoxide over coal gangue hollow ball. Fuel Processing Technology, 125: 163–169

[31] Liao X, Shao J, Zhang S, Li X, Yang H, Wang X, Chen H. (2019). Effects of CO₂ and CO on the reduction of NO over calcined limestone or char in oxy-fuel fluidised bed combustion. IET Renewable Power Generation, 13(10): 1633–1640

[32] Liu Y. (2022). Reduction mechanism of NO gas on iron-phthalocyanines (Fe-PCs): a DFT investigation. Catalysis Letters, 152(5): 1338–1346

[33] Ma S, Cheng F, Lu P, Song T. (2022). Enhanced performance of hematite oxygen carrier by CeO₂ for chemical looping hydrogen generation. International Journal of Hydrogen Energy, 47(8): 5130–5141

[34] Mantri D, Aghalayam P. (2007). Detailed surface reaction mechanism for reduction of NO by CO. Catalysis Today, 119(1−4): 88–93

[35] Mao X, Zhang Y, Xu Y, Zhou Y, Zhuang K, Shen K, Ding S. (2024). The lattice oxygen determines the methanol selectivity in CO₂ hydrogenation over ZnZrO_x catalysts. Catalysis Science & Technology, 14(2): 419–430

[36] Normann F, Andersson K, Johnsson F, Leckner B. (2011). NO_x reburning in oxy-fuel combustion: a comparison between solid and gaseous fuels. International Journal of Greenhouse Gas Control, 5: S120–S126

[37] Patel V, Sharma S. (2021). Effect of oxide supports on palladium based catalysts for NO reduction by H₂-SCR. Catalysis Today, 375: 591–600

[38] Pisupati S, Bhalla S. (2008). Numerical modeling of NO_x reduction using pyrolysis products from biomass-based materials. Biomass and Bioenergy, 32(2): 146–154

[39] Shu Y, Zhang F, Wang H, Zhu J, Tian G, Zhang C, Cui Y, Huang J. (2015). An experimental study of NO reduction by biomass reburning and the characterization of its pyrolysis gases. Fuel, 139: 321–327

[40] Song Y, Wang T, Cheng L, Li C, Wang H, Wang X. (2019). Simultaneous removal of SO₂ and NO by CO reduction over prevulcanized Fe₂O₃/AC catalysts. Canadian Journal of Chemical Engineering, 97(7): 2015–2020

[41] Sun P, Cheng X, Lai Y, Wang Z, Ma C, Chang J. (2018). NO_x reduction by CO over ASC catalysts in a simulated rotary reactor: effect of CO₂, H₂O and SO₂. RSC Advances, 8(64): 36604–36615

[42] Wang X, Liu W, Zhang T, Sun X, Liang D, Lin L. (2000). Kinetics of the selective reduction of NO with CH₄ over an In-Fe₂O₃/HZSM-5 catalyst. Reaction Kinetics and Catalysis Letters, 69(2): 299–303

[43] Williams B, Fleming J. (1994). Comparative species concentrations in CH₄/O₂/Ar flames doped with N₂O, NO, and NO₂. Combustion and Flame, 98(1−2): 93–106

[44] Wu B, Pu G, Du J. (2018). Experiment and simulation study of the effect of ethanol and compound additives on the urea-based selective non-catalytic reduction process under moderate temperature conditions. Royal Society Open Science, 5(10): 180969

[45] Wu H, Cai J, Ren Q, Shi C, Zhao A, Lyu Q. (2020a). A thermal and chemical fuel pretreatment process for NO_x reduction from cement kiln. Fuel Processing Technology, 210: 106556

[46] Wu H, Ren Q, Cai J, Lyu Q. (2020b). Research on the dynamic process of NO heterogeneous and homogeneous reduction with cement raw meal in vertical tubular reactor. Journal of the Energy Institute, 93(3): 878–888

[47] Wu H, Zhang Y, Ren Q, Wang Y, Lyu Q. (2019). Impact of residual carbon on ash fusibility of semi-char from an industrial circulating fluidized bed gasifier. Energy & Fuels, 33(1): 531–540

[48] Xiao X, Tan J, Yuan J, Fang P, Huang J, Tang Z, Wu H, Hu S. (2022). Dual role of O₂ concentration on the reducing gases produced and no reduction during sewage sludge combustion in pilot scale cement precalciner. Waste Management, 137: 100–109

[49] Xu Y, Wang X, Qin M, Li Q. (2022). Selective catalytic reduction of NO_x with CH₄ over zeolite catalysts: research progress, challenges and perspectives. Journal of Environmental Chemical Engineering, 10(2): 107270

[50] Xu Z, Li Y, Lin Y, Zhu T. (2020). A review of the catalysts used in the reduction of NO by CO for gas purification. Environmental Science and Pollution Research International, 27(7): 6723–6748

[51] Yang X, Zhao B, Zhuo Y, Chen C, Xu X. (2011). Effects of water vapor, CO₂ and SO₂ on the no reduction by NH₃ over sulfated CaO. Korean Journal of Chemical Engineering, 28(8): 1785–1790

[52] Zhang M, Wang M, Xu B, Ma D. (2019). How to measure the reaction performance of heterogeneous catalytic reactions reliably. Joule, 3(12): 2876–2883

[53] Zhao J, Li Z, Zhu R, Zhang J, Ding R, Wen Z, Zhu Y, Zhang G, Chen B. (2021). Mechanism of the selective catalytic reduction of NO_x with CH₄ on In/H-beta. Catalysis Science & Technology, 11(15): 5050–5061

[54] Zhao J, Wang Q, Yu L, Wu L. (2016). Influence of the biogas reburning for reducing nitric oxide emissions in an alundum-tube reactor. Atmospheric Environment, 132: 290–295

[55] Zheng C, Zhang H, Cai X, Chen L, Liu M, Lin H, Wang X. (2021). Characteristics of CO₂ and atmospheric pollutant emissions from China’s cement industry: a life-cycle perspective. Journal of Cleaner Production, 282: 124533

RIGHTS & PERMISSIONS

Higher Education Press 2025