Ce掺杂对Pd/γ-Al_2O_3催化燃烧甲苯性能的影响
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摘要
过等体积浸渍法制备了单金属Pd/γ-Al_2O_3催化剂和双金属Pd-Ce/γ-Al_2O_3催化剂,考察掺杂CeO_2对Pd/γ-Al_2O_3催化剂催化氧化甲苯性能的影响.并通过N_2吸脱附、SEM、H_2-TPR表征催化剂比表面积、表面形貌及氧化还原性能.结果发现,CeO_2的掺杂一定程度上降低了Pd/γ-Al_2O_3催化剂的比表面积,但增加了10nm孔径的孔密度,且催化剂仍保持介孔结构,当添加4%CeO_2时(质量分数,下同),催化剂比表面积降至165m~2/g,孔道存在一定程度的堵塞,阻碍污染物和反应产物的扩散,降低催化剂催化性能.H_2-TPR结果表明,Pd和Ce之间存在较强的协同作用,与PdO相邻的CeO_2更容易打开Ce—O键,相较于单金属0.2%Pd/γ-Al_2O_3,掺杂了0.3%CeO_2的催化剂具有更强的还原峰,表明CeO_2的引入为催化剂提供了更多的表面氧空位,增强了催化剂的催化氧化能力,其T_(10)和T_(90)与单贵金属催化剂相比分别降低10和40℃.
A single metal Pd/γ-Al_2O_3 catalyst and a bimetallic Pd-Ce/γ-Al_2O_3 catalyst were prepared by equal volume impregnation method to investigate the effect of CeO_2 doping on the catalytic oxidation of toluene.The specific surface area,surface morphology and redox properties of the catalyst were characterized with N_2 desorption,SEM and H_2-TPR.It was found that the doping of CeO_2reduced the specific surface area of Pd/γ-Al_2O_3 catalyst to a certain extent,but increased the pore density of 10nm,and the catalyst still maintained the mesoporous structure.When 4%CeO_2 was added(mass fraction,the same below),the specific surface area of the catalyst was reduced to 165m~2/g,and there was a certain degree of clogging in the pores,which hindered the diffusion of pollutants and reaction products,and reduced the catalytic performance of the catalyst.The H_2-TPR results showed that there is a strong synergistic effect between Pd and Ce.CeO_2 adjacent to PdO was more likely to open Ce-O bond,which was 0.3compared with single metal 0.2%Pd/γ-Al_2O_3 catalyst.The catalyst of%CeO_2 had a stronger reduction peak,indicating that the introduction of Ce O_2provided more surface oxygen vacancies for the catalyst and enhances the catalytic oxidation ability of the catalyst.in which the T_(10)and T_(90) were reduced by 10 and 40 respectively.℃℃
A single metal Pd/γ-Al_2O_3 catalyst and a bimetallic Pd-Ce/γ-Al_2O_3 catalyst were prepared by equal volume impregnation method to investigate the effect of CeO_2 doping on the catalytic oxidation of toluene.The specific surface area,surface morphology and redox properties of the catalyst were characterized with N_2 desorption,SEM and H_2-TPR.It was found that the doping of CeO_2reduced the specific surface area of Pd/γ-Al_2O_3 catalyst to a certain extent,but increased the pore density of 10nm,and the catalyst still maintained the mesoporous structure.When 4%CeO_2 was added(mass fraction,the same below),the specific surface area of the catalyst was reduced to 165m~2/g,and there was a certain degree of clogging in the pores,which hindered the diffusion of pollutants and reaction products,and reduced the catalytic performance of the catalyst.The H_2-TPR results showed that there is a strong synergistic effect between Pd and Ce.CeO_2 adjacent to PdO was more likely to open Ce-O bond,which was 0.3compared with single metal 0.2%Pd/γ-Al_2O_3 catalyst.The catalyst of%CeO_2 had a stronger reduction peak,indicating that the introduction of Ce O_2provided more surface oxygen vacancies for the catalyst and enhances the catalytic oxidation ability of the catalyst.in which the T_(10)and T_(90) were reduced by 10 and 40 respectively.℃℃
引文
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[30]胡嘉,刘昕,苏伟康,等.PVP辅助分散对Pd/SBA-15催化剂上甲苯催化燃烧性能的影响[J].环境工程学报,2018,12(11):3116-3123.Hu J,Liu X,Su W,et al.PVP assisted dispersion on toluene catalytic combustion on Pd/SBA-15catalyst effect of burning performance[J].Chinese Journal of Environmental Engineering,2018,12(11):3116-3123.
[31]黄敬敬,贾志刚,刘翻艳.Ce改性Pd基整体式催化剂的结构特征及其甲烷催化燃烧性能[J].工业催化,2013,21(5):23-29.Huang J,Jia Z,Liu F.Catalytic combustion of lean methane over Pd/γ-Al2O3/Cord monolith catalysts modified by Ce[J].Industrial Catalysis,2013,21(5):23-29.
[32]Tidahy H L,Hosseini M,Siffert S,et al.Nanostructured macromesoporous zirconia impregnated by noble metal for catalytic total oxidation of toluene[J].Catalysis Today,2008,137(2-4):335-339.
[33]Giraudon J M,Elhachimi A,Wyrwalski F,et al.21Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene[J].Applied Catalysis B:Environmental,2007,75(3/4):157-166.
[34]Gil S,Garcia-Vargas J,Liotta L,et al.Catalytic oxidation of propene over Pd catalysts supported on CeO2,TiO2,Al2O3,and M/Al2O3Oxides(M=Ce,Ti,Fe,Mn)[J].Catalysts,2015,5(2):671-689.
[35]López J M,Gilbank A L,García T,et al.The prevalence of surface oxygen vacancies over the mobility of bulk oxygen in nanostructured ceria for the total toluene oxidation[J].Applied Catalysis B:Environmental,2015,174-175:403-412.
[36]Liu L,Song Y,Fu Z,et al.Effect of preparation method on the surface characteristics and activity of the Pd/OMS-2catalysts for the oxidation of carbon monoxide,toluene,and ethyl acetate[J].Applied Surface Science,2017,396:599-608.
[37]Si R,Flytzani-Stephanopoulos M.Shape and crystal-plane effects of nanoscale ceria on the activity of Au-CeO2 catalysts for the water-gas shift reaction[J].Angewandte Chemie International Edition,2008,47(15):2884-2887.
[38]Vayssilov G N,Lykhach Y,Migani A,et al.Support nanostructure boosts oxygen transfer to catalytically active platinum nanoparticles[J].Nature Materials,2011,10(4):310-315.
[39]Cheng Z,Chen Z,Li J,et al.Mesoporous silica-pillared clays supported nanosized Co3O4-CeO2 for catalytic combustion of toluene[J].Applied Surface Science,2018,459:32-39.
[2]江梅,邹兰,李晓倩,等.我国挥发性有机物定义和控制指标的探讨[J].环境科学,2015,36(9):3522-3532.Su M,Zou L,Li X,et al.Definition and control indicators of volatile organic compounds in China[J].Environment Science,2015,36(9):3522-3532.
[3]Dumanoglu Y,Kara M,Altiok H,et al.Spatial and seasonal variation and source apportionment of volatile organic compounds(VOCs)in a heavily industrialized region[J].Atmospheric Environment,2014,98:168-178.
[4]Zhang X,Xue Z,Li H,et al.Ambient volatile organic compounds pollution in China[J].Journal of Environmental Sciences,2017,55:69-75.
[5]Kamal M S,Razzak S A,Hossain M M.Catalytic oxidation of volatile organic compounds(VOCs)-A review[J].Atmospheric Environment,2016,140:117-134.
[6]Fan Z,Zhang Z,Fang W,et al.Low‐temperature catalytic oxidation of formaldehyde over Co3O4 catalysts prepared using various precipitants[J].Chinese Journal of Catalysis,2016,37(6):947-954.
[7]Zhang C,Wang C,Zhan W,et al.Catalytic oxidation of vinyl chloride emission over LaMnO3 and LaB0.2Mn0.8O3(B=Co,Ni,Fe)catalysts[J].Applied Catalysis B:Environmental,2013,129:509-516.
[8]Ye Z,Giraudon J M,Nuns N,et al.Influence of the preparation method on the activity of copper-manganese oxides for toluene total oxidation[J].Applied Catalysis B:Environmental,2018,223:154-166.
[9]Meng Q,Liu J,Weng X,et al.In situ valence modification of Pd/NiOnano-catalysts in supercritical water towards toluene oxidation[J].Catalysis Science&Technology,2018,8(7):1858-1866.
[10]Chen J,Chen X,Xu W,et al.Hydrolysis driving redox reaction to synthesize Mn-Fe binary oxides as highly active catalysts for the removal of toluene[J].Chemical Engineering Journal,2017,330:281-293.
[11]Peng R,Li S,Sun X,et al.Size effect of Pt nanoparticles on the catalytic oxidation of toluene over Pt/CeO2 catalysts[J].Applied Catalysis B:Environmental,2018,220:462-470.
[12]de Castro T P,Silveira E B,Rabelo-Neto R C,et al.Study of the performance of Pt/Al2O3 and Pt/CeO2/Al2O3 catalysts for steam reforming of toluene,methane,and mixtures[J].Catalysis Today,2018,299:251-262.
[13]Li W,Ye H,Liu G,et al.The role of graphene coating on cordieritesupported Pd monolithic catalysts for low‐temperature combustion of toluene[J].Chinese Journal of Catalysis,2018,5(39):946-954.
[14]Barakat T,Rooke J,Chlala D,et al.Oscillatory behavior of Pd-Au catalysts in toluene total oxidation[J].Catalysts,2018,8(12):574.
[15]Yang H,Deng J,Liu Y,et al.Preparation and catalytic performance of Ag,Au,Pd or Pt nanoparticles supported on 3DOM CeO2-Al2O3 for toluene oxidation[J].Journal of Molecular Catalysis A:Chemical,2016,414:9-18.
[16]Fu X,Liu Y,Yao W,et al.One-step synthesis of bimetallic Pt-Pd/MCM-41mesoporous materials with the superior catalytic performance for toluene oxidation[J].Catalysis Communications,2016,83:22-26.
[17]Li W,Ye H,Liu G,et al.The role of graphene coating on cordieritesupported Pd monolithic catalysts for low-temperature combustion of toluene[J].Chinese Journal of Catalysis,2018,39(5):946-954.
[18]林涛,万克柔,程杰,等.低浓度甲苯催化燃烧蜂窝陶瓷催化剂的制备[J].山东化工,2018,47(5):55-57.Lin T,Wang K,Cheng J,et al.Preparation of catalysts applied to the catalytic combustion of low concentration toluene[J].Shangdong Chemcial Industry,2018,47(5):55-57.
[19]Ilieva L,Venezia A,Petrova P,et al.Effect of Y modified ceria support in mono and bimetallic Pd-Au catalysts for complete benzene oxidation[J].Catalysts,2018,8(7):283.
[20]Liu P,Zhao Y,Qin R,et al.A vicinal effect for promoting catalysis of Pd1/TiO2:supports of atomically dispersed catalysts play more roles than simply serving as ligands[J].Science Bulletin,2018,63(11):675-682.
[21]Li W,Ye H,Liu G,et al.The role of graphene coating on cordieritesupported Pd monolithic catalysts for low-temperature combustion of toluene[J].Chinese Journal of Catalysis,2018,39(5):946-954.
[22]Huang S,Zhang C,He H.Effect of pretreatment on Pd/Al2O3 catalyst for catalytic oxidation of o-xylene at low temperature[J].J Environ Sci(China),2013,25(6):1206-1212.
[23]孙梦君,柳丽芬,杨凤林.β-环糊精/Ce/TiO2光催化氧化气相甲苯[J].中国环境科学,2008,28(7):593-598.Sun M,Liu L,Yang F.Photocatalytie oxidation of toluene gas usingβ-CD modified Ce/TiO2[J].China Environmental Science,2008,28(7):593-598.
[24]Liao H,Zuo P,Liu M.Study on the correlation between the surface active species of Pd/cordierite monolithic catalyst and its catalytic activity[J].Materials Science and Engineering:B,2016,211:45-52.
[25]曹利,黄学敏,冯燕.掺杂CeO2的CuMnOx复合氧化物催化剂的制备及对甲苯催化燃烧性能研究[J].西安建筑科技大学学报(自然科学版),2010,42(5):729-733.Cao L,Huang X,Feng Y.Preparation of CuMnOx composite oxide catalyst doped with CeO2 and its catalytic performance for toluene[J].J.Xi’an Univ.of Arch.&.Tech.(Natural Science Edition),2010,42(5):729-733.
[26]何丽芳,廖银念,陈礼敏,等.纳米CeO2催化氧化甲苯的形貌效应研究[J].环境科学学报,2013,33(9):2412-2421.He L,Liao Y,Chen L,et al.Shape effect of ceria nanocrystals with various morphologies on toluene catalytic oxidation[J].Acta Scientiae Circumstantiae,2013,33(9):2412-2421.
[27]焦向东,斌盛,陈梦霞,等.Pd-Pt-Ce/Al2O3催化剂在VOC净化处理中的催化性能[J].工业催化,2016,42(5):31-33.Jiao X,Bin S,Chen M,et al.Catalytic performance of Pd-PtCe/Al2O3 catalysts for VOC puri6cation treatment[J].Industrial Catalysis,2016,42(5):31-33.
[28]Zuo S,Sun X,Lv N,et al.Rare earth-modified kaolin/NaY-supported Pd-Pt bimetallic catalyst for the catalytic combustion of benzene[J].ACS Applied Materials&Interfaces,2014,6(15):11988-11996.
[29]胡凌霄,王莲,王飞,等.Pd/γ-Al2O3催化剂催化氧化邻-二甲苯[J].物理化学学报,2017,33(8):1681-1688.Hu L X,Wang L,Wang F,et al.Catalytic oxidation of o-xylene over Pd/γ-Al2O3 catalysts[J].Acta Physica Sinica,2017,33(8):1681-1688.
[30]胡嘉,刘昕,苏伟康,等.PVP辅助分散对Pd/SBA-15催化剂上甲苯催化燃烧性能的影响[J].环境工程学报,2018,12(11):3116-3123.Hu J,Liu X,Su W,et al.PVP assisted dispersion on toluene catalytic combustion on Pd/SBA-15catalyst effect of burning performance[J].Chinese Journal of Environmental Engineering,2018,12(11):3116-3123.
[31]黄敬敬,贾志刚,刘翻艳.Ce改性Pd基整体式催化剂的结构特征及其甲烷催化燃烧性能[J].工业催化,2013,21(5):23-29.Huang J,Jia Z,Liu F.Catalytic combustion of lean methane over Pd/γ-Al2O3/Cord monolith catalysts modified by Ce[J].Industrial Catalysis,2013,21(5):23-29.
[32]Tidahy H L,Hosseini M,Siffert S,et al.Nanostructured macromesoporous zirconia impregnated by noble metal for catalytic total oxidation of toluene[J].Catalysis Today,2008,137(2-4):335-339.
[33]Giraudon J M,Elhachimi A,Wyrwalski F,et al.21Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene[J].Applied Catalysis B:Environmental,2007,75(3/4):157-166.
[34]Gil S,Garcia-Vargas J,Liotta L,et al.Catalytic oxidation of propene over Pd catalysts supported on CeO2,TiO2,Al2O3,and M/Al2O3Oxides(M=Ce,Ti,Fe,Mn)[J].Catalysts,2015,5(2):671-689.
[35]López J M,Gilbank A L,García T,et al.The prevalence of surface oxygen vacancies over the mobility of bulk oxygen in nanostructured ceria for the total toluene oxidation[J].Applied Catalysis B:Environmental,2015,174-175:403-412.
[36]Liu L,Song Y,Fu Z,et al.Effect of preparation method on the surface characteristics and activity of the Pd/OMS-2catalysts for the oxidation of carbon monoxide,toluene,and ethyl acetate[J].Applied Surface Science,2017,396:599-608.
[37]Si R,Flytzani-Stephanopoulos M.Shape and crystal-plane effects of nanoscale ceria on the activity of Au-CeO2 catalysts for the water-gas shift reaction[J].Angewandte Chemie International Edition,2008,47(15):2884-2887.
[38]Vayssilov G N,Lykhach Y,Migani A,et al.Support nanostructure boosts oxygen transfer to catalytically active platinum nanoparticles[J].Nature Materials,2011,10(4):310-315.
[39]Cheng Z,Chen Z,Li J,et al.Mesoporous silica-pillared clays supported nanosized Co3O4-CeO2 for catalytic combustion of toluene[J].Applied Surface Science,2018,459:32-39.