涂层组分对堇青石脱硝催化剂性能的影响
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摘要
为了探究涂层组分对整体式低温选择性催化还原(SCR)脱硝催化剂性能的影响,本文使用锰氧化物(MnO_x)、氧化物涂层(TiO_2、SiO_2及Al_2O_3)、堇青石(CC)基体制备整体式涂层催化剂,考察催化剂牢固度以及脱硝活性。结果表明:在200℃时,对于MnO_x/Al_2O_3/CC催化剂,MnO_x负载率为6%(质量分数)时脱硝效率最高为95%;对于MnO_x/TiO_2/CC,负载率为6%～12%时脱硝效率相差不大,为75%左右;对于MnO_x/SiO_2/CC,负载率12%时脱硝效率80%。样品牢固度排列顺序如下:MnO_x/Al_2O_3/CC> MnO_x/SiO_2/CC> MnO_x/TiO_2/CC。通过BET、SEM、TG、Raman、H_2-TPR等测试与分析方法发现:影响催化剂性能的因素主要为活性组分MnO_x状态以及载体性能的差异。Al_2O_3涂层比表面积适中,作为载体活性好;SiO_2涂层虽然比表面积大、牢固度好,但作为载体活性差;TiO_2作为涂层比表面积较小,溶胶中溶剂挥发快使得涂层表面不均匀。
In order to explore the influence of coating components on the performance of monolithic SCR denitration catalysts, manganese oxide(MnO_x), oxides(TiO_2, SiO_2, and Al_2O_3) coatings and Honeycomb Cordierite(CC) substrate were selected to prepare structured coating catalysts, and the firmness and the denitrification activity of the catalysts were investigated. The denitration results showed that, for MnO_x/Al_2O_3/CC catalysts, the denitrification efficiency at 200℃ was up to 95% when MnO_xloading amount was6%. The efficiency was about 75% for MnO_x/TiO_2/CC as the loading was from 6% to 12% and it was 80%with 12% loading for the MnO_x/SiO_2/CC. The sample firmness was in the order: MnO_x/Al_2O_3/CC>MnO_x/SiO_2/CC>MnO_x/TiO_2/CC. Through BET, SEM, TG, Raman, H_2-TPR and other analysis methods, it was found that the differences between the state of active component MnO_xand the performance of the carrier were the main influence factors on the performance of catalysts. The Al_2O_3 coating had moderate specific surface area, and showed good activity as carrier. SiO_2 coating had high specific surface area and good firmness, but it acted poorly as carrier. TiO_2 had relatively small specific surface area, and the solvent evaporation in the sol was fast, resulting in an uneven coating surface uneven.
In order to explore the influence of coating components on the performance of monolithic SCR denitration catalysts, manganese oxide(MnO_x), oxides(TiO_2, SiO_2, and Al_2O_3) coatings and Honeycomb Cordierite(CC) substrate were selected to prepare structured coating catalysts, and the firmness and the denitrification activity of the catalysts were investigated. The denitration results showed that, for MnO_x/Al_2O_3/CC catalysts, the denitrification efficiency at 200℃ was up to 95% when MnO_xloading amount was6%. The efficiency was about 75% for MnO_x/TiO_2/CC as the loading was from 6% to 12% and it was 80%with 12% loading for the MnO_x/SiO_2/CC. The sample firmness was in the order: MnO_x/Al_2O_3/CC>MnO_x/SiO_2/CC>MnO_x/TiO_2/CC. Through BET, SEM, TG, Raman, H_2-TPR and other analysis methods, it was found that the differences between the state of active component MnO_xand the performance of the carrier were the main influence factors on the performance of catalysts. The Al_2O_3 coating had moderate specific surface area, and showed good activity as carrier. SiO_2 coating had high specific surface area and good firmness, but it acted poorly as carrier. TiO_2 had relatively small specific surface area, and the solvent evaporation in the sol was fast, resulting in an uneven coating surface uneven.
引文
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[20]FU Z B,XIE J L,HE F,et al.Synthesis of porous cordierite and application for MnOx/TiO2catalyst support[J].Russian Journal of Applied Chemistry,2014,87(11):1749-1754.
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[2]QIU Y,LIU B,DU J,et al.The monolithic cordierite supported V2O5-MoO3/TiO2catalyst for NH3-SCR[J].Chemical Engineering Journal,2016,294:264-272.
[3]SU J,LIU Q,LIU Z,et al.Honeycomb CuO/Al2O3/cordierite catalyst for selective catalytic reduction of NO by NH3--effect of Al2O3coating[J].Industrial&Engineering Chemistry Research,2008,47(13):4295-4301.
[4]WANG T,YANG S,SUN K,et al.Preparation of Pt/beta zeolite-Al2O3/cordierite monolith for automobile exhaust purification[J].Ceramics International,2011,37(2):621-626.
[5]BUENO-LóPEZ A,LOZANO-CASTELLóD,SUCH-BASá?EZ I,et al.Preparation of beta-coated cordierite honeycomb monoliths by in situ synthesis:utilisation as Pt support for NOx abatement in diesel exhaust[J].Applied Catalysis B:Environmental,2005,58(1/2):1-7.
[6]黄海凤,张峰,卢晗锋,等.制备方法对低温NH3-SCR脱硝催化剂MnOx/TiO2结构与性能的影响[J].化工学报,2010,61(1):80-85.HUANG H F,ZHANG F,LU H F,et al.Effect of preparation methods on structures and performance of MnOx/TiO2catalyst for lowtemperature NH3-SCR[J].CIESC Journal,2010,61(1):80-85.
[7]ZHANG X,XIE C,YONG G,et al.Preparation and performance of honeycomb MnOx/PG-CC catalysts for low temperature NO removal by SCR[J].Environmental Chemistry,2015,34(4):615-626.
[8]WANG J,PENG Z,YING C,et al.In-situ hydrothermal synthesis of Cu-SSZ-13/cordierite for the catalytic removal of NOx,from diesel vehicles by NH3[J].Chemical Engineering Journal,2015,263(11):9-19.
[9]SMIRNIOTIS P G,SREEKANTH P M,PE?A D A,et al.Manganese oxide catalysts supported on TiO2,Al2O3,and SiO2:a comparison for low-temperature SCR of NO with NH3[J].Industrial&Engineering Chemistry Research,2006,45(19):6436-6443.
[10]黄海凤,周小燕,卢晗锋,等.原位沉淀技术制备整体型Mn/Ti-Si/堇青石选择性催化还原催化剂[J].中国电机工程学报,2011,31(17):50-54.HUANG H F,ZHOU X Y,LU H F,et al.Monolithic Mn/Ti-Si/cordierite catalyst prepared by in-situ deposition for SCR-deNOx[J].Proceedings of the CSEE,2011,31(17):50-54.
[11]ETTIREDDY P R,ETTIREDDY N,MAMEDOV S,et al.Surface characterization studies of TiO2supported manganese oxide catalysts for low temperature SCR of NO with NH3[J].Applied Catalysis B:Environmental,2007,76(1/2):123-134.
[12]BILAL M,JACKSON S D.Ethanol steam reforming over Pt/Al2O3and Rh/Al2O3catalysts:the effect of impurities on selectivity and catalyst deactivation[J].Applied Catalysis A:General,2017,529:98-107.
[13]BAJUS S,AGEL F,KUSCHE M.Alkali hydroxide-modified Ru/γ-Al2O3catalysts for ammonia decomposition[J].Applied Catalysis A:General,2016,510:189-195.
[14]HU X C,WANG W W,GU Y Q,et al.Co-SiO2nanocomposite catalysts for COx-free hydrogen production by ammonia decomposition[J].Chempluschem,2017,82(3):368-375.
[15]GINSBURG A,KELLER D A,BARAD H N,et al.One-step synthesis of crystalline Mn2O3thin film by ultrasonic spray pyrolysis[J].Thin Solid Films,2016,615:261-264.
[16]GAO T,FJELLVG H,NORBY P,et al.A comparison study on Raman scattering properties of alpha-and beta-MnO2[J].Analytica Chimica Acta,2009,648(2):235.
[17]XU J,DENG Y Q,ZHANG X M,et al.Preparation,characterization,and kinetic study of a core-shell Mn3O4@SiO2nanostructure catalyst for CO oxidation[J].ACS Catalysis,2014,4(11):4106-4115.
[18]XIE J,FANG D,HE F,et al.Performance and mechanism about MnOx species included in MnOx/TiO2,catalysts for SCR at low temperature[J].Catalysis Communications,2012,28(44):77-81.
[19]FANG D,HE F,XIE J L,et al.Distributions and species of MnOx included in MnOx/TiO2catalysts for denitration at low temperature[J].Materials Science Forum,2013,743/744:269-274.
[20]FU Z B,XIE J L,HE F,et al.Synthesis of porous cordierite and application for MnOx/TiO2catalyst support[J].Russian Journal of Applied Chemistry,2014,87(11):1749-1754.
[21]师昌绪.材料大辞典[M].北京:化学工业出版社,1994.SHI C X.Material dictionary[M].Beijing:Chemical Industry Press,1994.
[22]赵鹏,陈爱城,戴勇.二氧化硅表面硅羟基含量的测定方法[J].广州化工,2016,44:30-32.ZHAO P,CHEN A C,DAI Y.The method for determination of silanol on silica surface[J].Guangzhou Chemical Industry,2016,44:30-32.
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