低温燃烧法制备Mn-CeO_x催化剂及其NH_3-SCR脱硝性能
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摘要
通过低温燃烧法(LCS)制备了不同金属硝酸盐与柠檬酸物质的量比的系列Mn-CeO_x(LCS)锰铈催化剂,将其与共沉淀法(CP)制备的Mn-CeO_x(CP)锰铈催化剂相对比,结合XRD、XPS、FESEM和H2-TPR等技术表征,对其NH_3-SCR脱硝催化性能进行了研究。结果表明,金属硝酸盐与柠檬酸的物质的量比是影响Mn-CeO_x(LCS)催化剂脱硝性能的重要因素。虽然两种催化剂中的锰氧化物组分均为无定型,但相较于Mn-CeO_x(CP),Mn-CeO_x(LCS)表面具有较高的锰含量与Oα/(Oα+Oβ)比,其脱硝催化性能也较高;同时,Mn-CeO_x(LCS)锰铈催化剂上有更多的多级孔,有利于气体在催化剂上的吸附和反应。硝酸盐与柠檬酸物质的量比为36∶22的Mn-CeO_x(LCS)锰铈催化剂在80-180℃下脱硝率可达75%-100%;即使通入SO2,180℃下的脱硝率仍可稳定于74%。
A series of Mn-CeO_x( LCS) catalysts with different molar ratios of metal nitrates to citric acid were prepared by low-temperature combustion synthesis( LCS) method. Through a comparison with the Mn-CeO_x( CP) catalysts prepared by coprecipitation method( CP) as well as various characterization techniques such as XRD,XPS,FESEM,H2-TPR and nitrogen physisorption,the catalytic performance of Mn-CeO_x( LCS) in the selective catalytic reduction( SCR) of NOxby NH_3 was then investigated. The results showthat the molar ratio of metal nitrate to citric acid is an important factor affecting the denitrification performance of the Mn-CeO_x( LCS)catalysts. In comparison with the Mn-CeO_x( CP) catalysts,the Mn-CeO_x( LCS) catalysts are provided with a higher manganese content and high Oα/( Oα+Oβ) ratio on the surface as well as more hierarchical pores favorable for adsorption and reaction of reactants,which affords the Mn-CeO_x( LCS) catalysts much better denitrification performance. Over the Mn-CeO_x( LCS) catalyst with a molar ratio of metal nitrate to citric acid of 36 ∶22,the denitrification rate at 80-180 ℃ reaches 75%-100%; even in the presence of SO2,the denitrification rate over the Mn-CeO_x( LCS) catalyst at 180 ℃ keeps at the level of 74%.
A series of Mn-CeO_x( LCS) catalysts with different molar ratios of metal nitrates to citric acid were prepared by low-temperature combustion synthesis( LCS) method. Through a comparison with the Mn-CeO_x( CP) catalysts prepared by coprecipitation method( CP) as well as various characterization techniques such as XRD,XPS,FESEM,H2-TPR and nitrogen physisorption,the catalytic performance of Mn-CeO_x( LCS) in the selective catalytic reduction( SCR) of NOxby NH_3 was then investigated. The results showthat the molar ratio of metal nitrate to citric acid is an important factor affecting the denitrification performance of the Mn-CeO_x( LCS)catalysts. In comparison with the Mn-CeO_x( CP) catalysts,the Mn-CeO_x( LCS) catalysts are provided with a higher manganese content and high Oα/( Oα+Oβ) ratio on the surface as well as more hierarchical pores favorable for adsorption and reaction of reactants,which affords the Mn-CeO_x( LCS) catalysts much better denitrification performance. Over the Mn-CeO_x( LCS) catalyst with a molar ratio of metal nitrate to citric acid of 36 ∶22,the denitrification rate at 80-180 ℃ reaches 75%-100%; even in the presence of SO2,the denitrification rate over the Mn-CeO_x( LCS) catalyst at 180 ℃ keeps at the level of 74%.
引文
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[10]陈雪红,郑玉婴,付彬彬,郑伟杰.原位聚合Mn O2/PoPD@PPS复合滤料及其NH3-SCR脱硝性能研究[J].燃料化学学报,2017,45(12):1514-1521.(CHEN Xue-hong,ZHENG Yu-ying,FU Bin-bin,ZHENG Wei-jie. Preparation of Mn O2/PoPD@PPS functional composites for lowtemperature NO reduction w ith NH3[J]. J Fuel Chem Technol,2017,45(12):1514-1521.)
[11] QIAO J S,WANG N,WANG Z H,SUN W,SUN K N. Porous bimetallic Mn2Co1Oxcatalysts prepared by a one-step combustion method for the low temperature selective catalytic reduction of NOxw ith NH3[J]. Catal Commun,2015,72:111-115.
[12] MENG D M,ZHAN W C,GUO Y,GUO Y L,WANG L,LU G Z. A highly effective catalyst of Sm-Mn Oxfor the NH3-SCR of NOxat low temperature:Promotional role of Sm and its catalytic performance[J]. Acs Catal,2015,5:5973-5983.
[2] LIU C,SHI J W,GAO C,NIU C M. Manganese oxide-based catalysts for low-temperature selective catalytic reduction of NOxw ith NH3:A review[J]. Appl Catal A:Gen,2016,522:54-69.
[3] MENG L K,WANG J,SUN Z H,ZHU J X,LI H,WANG J Q,SHEN M Q. Active manganese oxide on MnOx-CeO2catalysts for lowtemperature NO oxidation:Characterization and kinetics study[J]. J Rare Earth,2018,36:142-147.
[4] XIA F T,SONG Z X,LIU X,LIU X,YANG Y H,ZHANG Q L,PENG J H. Improved catalytic activity and N2selectivity of Fe-M n-Ox catalyst for selective catalytic reduction of NO by NH3at low temperature[J]. Res Chem Interm,2018,44:2703-2717.
[5] ZHANG Z J,WANG W Z,SHANG M,YIN W Z. Low-temperature combustion synthesis of Bi2WO6nanoparticles as a visible-light-driven photocatalyst[J]. J Hazard M ater,2010,177:1013-1018.
[6]卢利平,张希艳,柏朝晖,米晓云.低温燃烧合成法研究进展[J].长春理工大学学报(自然科学版),2008,31(3):82-84.(LU Li-ping,ZHANG Xi-yan,BAI Zhao-hui,MI Xiao-yun. Research progress of low-temperature combustion synthesis method[J]. J Changchun Univ Sci Technol(Nat Sci Ed),2008,31(3):82-84.)
[7] JAYANTHI M,LAVANYA T,SARADHA N A,SATHEESH K,CHENTHAMARAI S,JAYAVEL R. Superior photocatalytic performance of CeO2nanoparticles and reduced graphene oxide nanocomposite prepared by low cost co-precipitation method[J]. J Nanosci Nanotechnol,2018,18(5):3257-3265.
[8] POURKHALIL M,MOGHADDAM A Z,RASHIDI A,TOWFIGHI J,JOZANI K J,BOZORGZADEH H. Synthesis of Mn Ox/oxidizedM WNTs for abatement of nitrogen oxides[J]. Catal Lett,2013,143(2):184-192.
[9] LIOTTA L,DI CARLO G,PANTALEO G,VENEZIA A,DEGANELLO G. Co3O4/CeO2composite oxides for methane emissions abatement:Relationship betw een Co3O4-CeO2interaction and catalytic activity[J]. Appl Catal B:Environ,2006,66(3/4):217-227.
[10]陈雪红,郑玉婴,付彬彬,郑伟杰.原位聚合Mn O2/PoPD@PPS复合滤料及其NH3-SCR脱硝性能研究[J].燃料化学学报,2017,45(12):1514-1521.(CHEN Xue-hong,ZHENG Yu-ying,FU Bin-bin,ZHENG Wei-jie. Preparation of Mn O2/PoPD@PPS functional composites for lowtemperature NO reduction w ith NH3[J]. J Fuel Chem Technol,2017,45(12):1514-1521.)
[11] QIAO J S,WANG N,WANG Z H,SUN W,SUN K N. Porous bimetallic Mn2Co1Oxcatalysts prepared by a one-step combustion method for the low temperature selective catalytic reduction of NOxw ith NH3[J]. Catal Commun,2015,72:111-115.
[12] MENG D M,ZHAN W C,GUO Y,GUO Y L,WANG L,LU G Z. A highly effective catalyst of Sm-Mn Oxfor the NH3-SCR of NOxat low temperature:Promotional role of Sm and its catalytic performance[J]. Acs Catal,2015,5:5973-5983.