Three-dimensionally ordered macroporous CeO_2/Al_2O_3-supported Au nanoparticle catalysts: Effects of CeO_2 nanolayers on catalytic activity in soot oxidation  

CeO_2纳米层对多层载体x-CeO_2/3DOM Al_2O_3负载纳米Au催化剂催化柴油炭烟燃烧活性的影响（英文）

作　　者：Baofang Jin Yuechang Wei Zhen Zhao Jian Liu Yazhao Li Renjie Li Aijun Duan Guiyuan Jiang 靳保芳;韦岳长;赵震;刘坚;李亚钊;李人杰;段爱军;姜桂元(中国石油大学(北京)重质油国家重点实验室,北京102249;沈阳师范大学能源与环境催化研究所,辽宁沈阳110034)

机构地区：[1]State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China [2]Institute of Catalysis for Energy and Environment, Shenyang Normal University, Shenyang 110034, Liaoning, China

出　　处：《Chinese Journal of Catalysis》2017年第9期1629-1641,共13页催化学报（英文）

基　　金：supported by the National High Technology Research and Development Program of China(863 Program,2015AA034603);the National Natural Science Foundation of China(21477146,21673142 and 21303263);the Beijing Nova Program(Z141109001814072);the Specialized Research Fund for the Doctoral Program of Higher Education(20130007120011);the Science Foundation of China University of Petroleum-Beijing(YJRC-2013-13,2462013BJRC003)~~

摘　　要：A series of catalysts consisting of three‐dimensionally ordered macroporous(3DOM)x‐CeO2/Al2O3‐supported Au nanoparticles(x=2,10,20,and40wt%)were successfully synthesized using a reduction‐deposition method.These catalysts were characterized using scanning electron microscopy,the Brunauer‐Emmett‐Teller method,X‐ray diffraction,transmission electron microscopy,ultraviolet‐visible spectroscopy,and temperature‐programmed reduction by H2.Au nanoparticles of mean particle size5nm were well dispersed and supported on the inner walls of uniform macropores.The3DOM structure improved the contact efficiency between soot and the catalyst.An Al‐Ce‐O solid solution was formed in the multilayer support,i.e.,x‐CeO2/Al2O3,by the incorporation of Al3+ions into the CeO2lattice,which resulted in the creation of extrinsic oxygen vacancies.Strong interactions between the metal(Au)and the support(Ce)increased the amount of active oxygen species,and this promoted soot oxidation.The catalytic performance in soot combustion was evaluated using a temperature‐programmed oxidation technique.The presence of CeO2nanolayers in the3DOM Au/x‐CeO2/Al2O3catalysts clearly improved the catalytic activities in soot oxidation.Among the prepared catalysts,3DOM Au/20%CeO2/Al2O3showed high catalytic activity and stability in diesel soot oxidation.与汽油车相比,柴油车具有CO_2排放低、寿命长和经济性好等优点,所以近年来受到广泛关注并被大量使用.但是,柴油车在使用过程中会产生大量炭烟颗粒物(PM),对大气环境和人类健康造成很大威胁.因此,开展这方面的基础研究具有重要的科学意义及环境保护意义.催化柴油炭烟燃烧反应是一个气-固-固多相深度氧化反应,由于PM的粒径远大于传统催化剂,导致PM不能进入催化剂孔道内部,造成催化剂活性比表面积利用率较低.设计并制备大孔径的三维有序大孔结构(3DOM)的催化剂,能够减小反应扩散阻力,增加催化剂与炭烟颗粒物的有效接触,加快反应进行.另外,可以通过在3DOM氧化物表面担载其它活性组分,提高催化剂的氧化还原性能,进而提高其活性.CeO_2有很好的储放氧性能,在柴油车尾气净化催化剂中较为常见,但是单一的CeO_2热稳定性较差,高温下容易烧结,使得比表面积减小,并且失去储氧能力,造成催化剂失活.文献中较常见的解决办法是在CeO_2中掺杂其它阳离子,如Zr^(4+),Pr^(3+),Al^(3+),La^(3+)及Y^(3+)等离子,以提高CeO_2的抗高温烧结能力.此外,研究报道的催化剂对催化柴油炭烟颗粒物燃烧的峰值温度已经远低于炭烟颗粒物的自燃温度,但是对颗粒物的起燃温度仍普遍较高.我们前期研究结果表明,担载纳米Au颗粒催化剂能够显著降低炭烟燃烧的起燃温度.本文采用胶体晶体模板法制备了3DOM Al_2O_3载体,利用微孔膜-氨沉淀法担载不同量的活性组分CeO_2,制备出一种负载型x-CeO_2/3DOM Al_2O_3催化剂,它既可减少稀土元素用量,降低成本,又因为Al_2O_3的机械强度较高,还能保证催化剂的机械强度足够好.为了进一步降低催化剂催化炭烟燃烧的起燃温度,利用还原沉积法在多层载体x-CeO_2/3DOM Al_2O_3上负载纳米Au催化剂,制备出不同厚度的CeO_2纳米层负载Au催化剂(Au/x-CeO_2/3DOM Al_2O_3).利用X�

关 键 词：Three‐dimensionally ordered macroporous material Gold nanoparticle Multilayer support CeO2 nanolayer Soot combustion 

分 类 号：O643.21[理学—物理化学] O643.36[理学—化学]