Pt颗粒尺寸对Pt/CeO_2催化氧化甲苯性能影响  

Effect of Pt particle size on Pt/CeO_2 catalyst for toluene catalytic oxidation

作　　者：孙西勃 彭若斯 李淑君[1] 梁小明[1] 陈礼敏[1,2,3,4] 付名利[1,2,3,4] 吴军良[1,2,3,4] 叶代启[1,2,3,4] 

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]广东省大气环境与污染控制重点实验室,广州510006 [3]大气污染控制广东高校工程技术研究中心华南理工大学,广州510006 [4]广东省环境风险防控与应急处置工程技术研究中心华南理工大学,广州510006

出　　处：《环境科学学报》2017年第4期1297-1306,共10页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.U1201231;51578245;51378218;51108187);国家高技术研究发展计划课题(No.2013AA065005);中央高校基本科研基金;广州市科技计划项目(No.201510010164);2015年广东省公益研究与能力建设专项(No.2015A020215010);2014年广东省自然科学基金博士科研启动项目(No.2014A030310431)~~

摘　　要：使用乙二醇还原法制备了一系列不同尺寸的Pt-x纳米颗粒(x=1.41、1.57、1.79、1.95、2.12、2.32 nm),将其负载于棒状(rod)CeO_2载体上.考察了不同尺寸的Pt颗粒催化剂Pt-x/CeO_2-rod在甲苯催化氧化反应中的催化性能.结果显示,随着Pt颗粒尺寸的增加,催化剂活性先升高后降低.其中,Pt颗粒尺寸为1.79 nm时催化剂催化活性最好,T90=133℃.一般认为,Pt颗粒尺寸增加其分散度减小,导致催化活性降低.然而本实验结果表明,随Pt尺寸增加催化活性先升高后降低,并且基于催化剂表面Pt原子计算的TOFs(turnover frequencies)随Pt尺寸增加逐渐变大.紫外拉曼光谱(UV Raman)、XRD、XPS显示,随着Pt颗粒尺寸增加,催化剂Pt-x/Ce-rod表面氧空位的浓度逐渐增加.氧空位有效提高了催化剂晶格氧的流动,促进了氧气的吸附活化及传递过程.Pt/Ce催化剂催化氧化甲苯反应活性是Pt分散度以及CeO_2表面氧空位浓度双重作用的结果.A series of Pt-x nanoparticles with different sizes （ x = 1.41, 1.57, 1.79, 1.95, 2.12 and 2.32 nm） were successfully synthesized by polyol reduction method and loaded onto CeO2-rod. These Pt-x/CeO2-rod samples were tested in the catalytic oxidation of toluene. The results indicated that the catalysts activity exhibited a volcano-shaped curve with respect to Pt particle size and Pt-1.79/CeO2-rod showed the highest catalytic activity with Tgo = 133℃. Commonly, an increased Pt particle size leads to a lower dispersion and worse catalytic performance. However, in this study, the activity of Pt/ CeO2 samples first increased and then decreased with the growth of Pt particle size. Moreover, the TOF calculated by the amount of exposed Pt atoms also increased with Pt size. UV Raman, XRD and XPS results showed increasing surface oxygen vacancies concentration along with increasing Pt particle sizes. The increase of surface oxygen vacancies accelerated the lattice oxygen transfer effectively and promote the adsorption and activation process of oxygen. Therefore, it could be concluded that the catalytic oxidation of toluene activity on Pt/CeO2 catalysts was a combined effect of Pt dispersion and CeO2 surface oxygen vacancies concentration.

关 键 词：甲苯 催化氧化 Pt尺寸效应 表面氧空位 CeO2纳米棒 

分 类 号：X51[环境科学与工程—环境工程]