EFFECT OF SYNTHESIS METHOD ON PERFORMANCE OF Ce-MnOx FOR SELECTIVE CATALYTIC OXIDATION OF AMMONIA
-
摘要: 分别采用水热法和浸渍法2种合成方法制备了Ce-MnOx催化剂,应用于氨的选择性催化氧化。实验结果表明:水热法制备的Ce-MnOx具有更高的催化氧化NH3活性,其中,在反应温度为200℃时,Ce(5)-MnOx(HY)具有98%的NH3转化率及91%的N2选择性。XRD、BET、Raman、XPS、SEM、H2-TPR等方法对催化剂的表征结果表明,水热法合成的Ce-MnOx具有更大的比表面积(94.37 m2/g),其优异的催化活性归因于表面丰富的Mn4+和Ce3+、大量的化学吸附氧、丰富的活性位点、Mn和Ce间的相互作用等。In-situ DRIFTS分析表明,催化剂表面吸附态的NH3经过脱氢作用生成—NH2、—NH中间体,其中,—NH与原子氧结合生成的—HNO能被O2快速氧化形成NO,NO再与—NH2继续反应生成N2和H2O。研究可为锰基催化剂在低温氨氧化及选择性方面的研究提供重要参考。Abstract: In this paper, Ce-MnOx was prepared for selective catalytic oxidation(SCO) of ammonia by hydrothermal and impregnation method respectively. The results demonstrated that Ce-MnOx catalysts exhibited the best NH3 oxidation activity which composited by hydrothermal method. Among them, Ce(5)-MnOx(HY) reached 98% of NH3 conversion rate and 91% of N2 selectivity, at reaction temperature of 200 ℃. The properties of the Ce-MnOx catalysts were analyzed by XRD, BET, Raman, XPS, SEM, and H2-TPR. Hydrothermally prepared Ce-MnOx possessed larger surface area(94.37 m2/g). At the same time, the distinguished catalytic activity of Ce-MnOx was attributed to abundant Mn4+ and Ce3+, high adsorbed oxygen concentration on the surface, a large number of active sites, and interaction between Mn and Ce. The results of in-situ DRIFTS showed that the —NH2 and —NH intermediates could be generated by adsorbed NH3 dehydrogenation. Consequently, —NH and atomic oxygen combined to form —HNO, which could be quickly oxidized to NO by O2. Finally, N2 and H2O were formed during the following reaction of NO with —NH2. This dissertation has significant reference value for the study of manganese-based catalysts in low-temperature ammonia oxidation and selectivity.
-
Key words:
- ammonia /
- selective catalytic oxidation /
- hydrothermal /
- impregnation /
- Ce-MnOx
-
[1] LI P X,ZHANG R D,LIU N,et al.Efficiency of Cu and Pd substitution in Fe-based perovskites to promote N2 formation during NH3 selective catalytic oxidation (NH3-SCO)[J].Applied Catalysis B:Environmental,2017,203:174-188. [2] PAN Y,TIAN S,LIU D,et al.Fossil fuel combustion-related emissions dominate atmospheric ammonia sources during severe haze episodes:evidence from (15)N-Stable isotope in size-resolved aerosol ammonium[J].Environmental Science & Technology,2016,50 (15):8049-8056. [3] WANG F,HE G Z,ZHANG B,et al.Insights into the activation effect of H2 pretreatment on Ag/Al2O3 catalyst for the selective oxidation of ammonia[J].ACS Catalysis,2019,9 (2):1437-1445. [4] 郭晶晶,李俊华,彭悦,等.铜前驱体对Cu/SSZ-13催化剂选择性催化氧化NH3性能的影响[J].环境科学学报,2019,39(11):3724-3731. [5] 唐晓龙,李东,王文勤,等.预处理对CNTs低温催化氧化NH3性能的影响[J].环境工程学报,2016,10(4):1939-1944. [6] WANG F,MA J Z,HE G Z,et al.Nanosize effect of Al2O3 in Ag/Al2O3 catalyst for the selective catalytic oxidation of ammonia[J].ACS Catalysis,2018,8(4):2670-2682. [7] 王慧敏,宁平,张秋林,等.不同RuO2含量对RuO2-Fe2O3催化剂氨选择性催化氧化性能的影响[J].燃料化学学报,2019,47(2):215-223. [8] SUN M M,LIU J Y,SONG C,et al.Different reaction mechanisms of ammonia oxidation reaction on Pt/Al2O3 and Pt/CeZrO2 with various Pt states[J].ACS Applied Materials Interfaces,2019,11(26):23102-23111. [9] ZHOU M D,WANG Z,SUN Q,et al.High-performance Ag-Cu nanoalloy catalyst for the selective catalytic oxidation of ammonia[J].ACS Applied Materials Interfaces,2019,11(50):46875-46885. [10] KADDOURI A,DUPONT N,GELIN P,et al.Selective oxidation of gas phase ammonia over copper chromites catalysts prepared by the sol-gel process[J].Catalysis Communications,2011,15(1):32-36. [11] GENG Y,SHAN W P,LIU F D,et al.Adjustment of operation temperature window of Mn-Ce oxide catalyst for the selective catalytic reduction of NOx with NH3[J].Journal of Hazardous Materials,2021,405:124223. [12] 周鹏飞,尤晓晨,李舒健,等.改性MnOx-CeO2/石墨烯催化剂低温SCR脱硝性能[J].环境工程,2018,36(11):94-99. [13] QU Z P,FAN R,WANG Z,et al.Selective catalytic oxidation of ammonia to nitrogen over MnO2 prepared by urea-assisted hydrothermal method[J].Applied Surface Science,2015,351:573-579. [14] 王文勤,唐晓龙.低温NH3选择性氧催化氧化研究[D].昆明:昆明理工大学,2013. [15] 从其良,马赫遥,杨鸣刚,等.新型花状CeO2的NH3-SCR性能及机制研究[J].高校化学工程学报,2020,3(34):810-815. [16] ZHANG X Y,WANG H,JIANG X,et al.Study of synergistic effect between CuO and CeO2 over CuO@CeO core-shell nanocomposites for NH3-SCO[J].Catalysis Science & Technology 2019,9:2968-2981. [17] BONINGARI T,ETTIREDDY P R,SOMOGYVARI A,et al.Influence of elevated surface texture hydrated titania on Ce-doped Mn/TiO2 catalysts for the low-temperature SCR of NOx under oxygen-rich conditions[J].Journal of Catalysis,2015,325 (5):145-155. [18] LIU Z M,YI Y,ZHANG S Y,et al.Selective catalytic reduction of NOx with NH3 over Mn-Ce mixed oxide catalyst at low temperatures[J].Catalysis Today,2013,216:76-81. [19] TANGX F,LI Y G,HUANG X M,et al.MnOx-CeO2 mixed oxide catalysts for complete oxidation of formaldehyde:effect of preparation method and calcination temperature[J].Applied Catalysis B:Environmental,2006,62(3/4):265-273. [20] HAN Z Y,WANG C,ZOU X H,et al.Diatomite-supported birnessite-type MnO2 catalytic oxidation of formaldehyde:preparation,performance and mechanism[J].Applied Surface Science,2019,502:144201. [21] REDDY B M,BHARILI P,THRIMURTHULU G,et al.Catalytic efficiency of ceria-zirconia and ceria-hafnia nanocomposite oxides for soot oxidation[J].Catalysis Letters,2008,123(3/4):327-333. [22] MCBRIDE J R,HASS K C,POINDEXTER B D,et al.Raman and x-ray studies of Ce1-xRExO2-y,where RE=La,Pr,Nd,Eu,Gd,and Tb[J].Journal of Applied Physics,1998,76(4):2435-2441. [23] QU Z P,KANG G,QIANG F,et al.Low-temperature catalytic oxidation of toluene over nanocrystal-like Mn-Co oxides prepared by two-step hydrothermal method[J].Catalysis Communications,2014,52(1):31-35. [24] LEE S M,PARK K H,HONG S C.MnOx/CeO2-TiO2 mixed oxide catalysts for the selective catalytic reduction of NO with NH3 at low temperature[J].Chemical Engineering Journal,2012,195/196:323-331. [25] FEI Z Y,YANG Y R,WANG M H,et al.Precisely fabricating Ce-O-Ti structure to enhance performance of Ce-Ti based catalysts for selective catalytic reduction of NO with NH3[J].Chemical Engineering Journal,2018,353:930-939. [26] 彭莎,刘志明.Ce基氧化物的形貌调控及其对NH3选择性催化还原NOx的研究[D].北京:北京工业大学,2017. [27] PAPPAS D K,BONOGARI T,BOOLCHAND P,et al.Novel manganese oxide confined interweaved titania nanotubes for the low-temperature selective catalytic reduction (SCR) of NOx by NH3[J].Journal of Catalysis,2016,334:1-13. [28] SERRANO L A,IGLESIAS J A,MONTE M,et al.MnO2-supported catalytic bodies for selective reduction of NO with NH3:influence of NO2 and H2O[J].Molecular Catalysis,2020,491:111004. [29] LI C C,LIU X H,LU G Z,et al.Redox properties and CO2 capture ability of CeO2 prepared by a glycol solvothermal method[J].Chinese Journal of Catalysis,2014,8(35):1346-1375. [30] CHEN X,XU X H,FEI Z Y,et al.CeO2 nanodots embedded in a porous silica matrix as an active yet durable catalyst for HCl oxidation[J].Catalysis Science & Technology,2016,6(13):5116-5123. [31] LI H L,WU C Y,LI Y,et al.Superior activity of MnOx-CeO2/TiO2 catalyst for catalytic oxidation of elemental mercury at low flue gas temperatures[J].Applied Catalysis B:Environmental,2012,111:381-388. [32] SEIFVAND N,KOWSARI E.TiO2/in-situ reduced GO/functionalized with an IL-Cr complex as a ternary photocatalyst composite for efficient carbon monoxide deterioration from air[J].Applied Catalysis B:Environmental,2017,206:184-193. [33] XIA Y S,DAI H X,ZHANG L,et al.Ultrasound-assisted nanocasting fabrication and excellent catalytic performance of three-dimensionally ordered mesoporous chromia for the combustion of formaldehyde,acetone,and methanol[J].Applied Catalysis B:Environmental,2010,100(1/2):229-237. [34] LI P X,ZHANG R D,LIU N,et al.Efficiency of Cu and Pd substitution in Fe-based perovskites to promote N2 formation during NH3 selective catalytic oxidation (NH3-SCO)[J].Applied Catalysis B:Environmental,2017,203:174-188. [35] YOU X C,SHENG Z Y,YU D Q,et al.Influence of Mn/Ce ratio on the physicochemical properties and catalytic performance of graphene supported MnOx-CeO2 oxides for NH3-SCR at low temperature[J].Applied Surface Science,2017,423:845-854. [36] WANG F,MA J Z,HE G Z,et al.Synergistic effect of TiO2-SiO2 in Ag/Si-Ti catalyst for the selective catalytic oxidation of ammonia[J].Industrial & Engineering Chemistry Research,2018,57(35):11903-11910. [37] 迟斌,曲虹霞.Cu-Ce-La-SSZ-13催化剂的制备及其脱硝性能研究[D].南京:南京理工大学,2018. [38] 于艳科,孟小然,陈进生,等.SO2对钾中毒SCR催化剂的活性促进作用研究[C]//中国环境科学学会.2014中国环境科学学会学术年会论文集.成都,2014:1-7. [39] QIU L,PANG D D,ZHANG C L,et al.In situ IR studies of Co and Ce doped Mn/TiO2 catalyst for low-temperature selective catalytic reduction of NO with NH3[J].Applied Surface Science,2015,357:189-196. [40] CHEN W M,MA Y P,QU Z,et al.Mechanism of the selective catalytic oxidation of slip ammonia over Ru-modified Ce-Zr complexes determined by in situ diffuse reflectance infrared fourier transform spectroscopy[J].Environmental Science & Technology,2014,48(20):12199-205. [41] LEE S M,LEE H H,HONG S C,Influence of calcination temperature on Ce/TiO2 catalysis of selective catalytic oxidation of NH3 to N2[J].Applied Catalysis A:General,2014,470:189-198. [42] ZHANG Q L,WANG H M,NING P,et al.In situ DRIFTS studies on CuO-Fe2O3 catalysts for low temperature selective catalytic oxidation of ammonia to nitrogen[J].Applied Surface Science,2017,419:733-743. [43] ZHANG L,HE H.Mechanism of selective catalytic oxidation of ammonia to nitrogen over Ag/Al2O3[J].Journal of Catalysis,2009,268(1):18-25. [44] 赵琳琳,黄亚继,宋静,等.V-W/TiO2/γ-Al2O3催化剂催化还原NO的研究[J].环境科学与技术,2012,35(5):85-89. [45] YANG S J,WANG C Z,LI J H,et al.Low temperature selective catalytic reduction of NO with NH3 over Mn-Fe spinel:performance,mechanism and kinetic study[J].Applied Catalysis B:Environmental,2011,110:71-80. [46] CHEN L,SI Z C,WU X D,et al.DRIFT study of CuO-CeO2-TiO2 mixed oxides for NOx reduction with NH3 at low temperatures[J].ACS Applied Materials Interfaces,2014,6(11):8134-45. [47] 易阳,刘志明.Cu-Ce-Ti催化剂上氨气选择性催化还原NOx的研究[D].北京:北京化工大学,2013. [48] YU X L,WU X M,CHEN Z Y,et al.Oxygen vacancy defect engineering in Mn-doped CeO2 nanostructures for nitrogen oxides emission abatement[J].Molecular Catalysis,2019,476:110512. [49] LIU J,LI X Y,ZHAO Q D,et al.Mechanistic investigation of the enhanced NH3-SCR on cobalt-decorated Ce-Ti mixed oxide:in situ FTIR analysis for structure-activity correlation[J].Applied Catalysis B:Environmental,2017,200:297-308.
点击查看大图
计量
- 文章访问数: 180
- HTML全文浏览量: 12
- PDF下载量: 4
- 被引次数: 0