掺杂Zr^(4+)对纳米Au/TiO_2催化剂结构和性能的影响  

Effect of Zr^(4+) Doping on Structures and Performance of Nano-Structured Au/TiO_2 Catalysts

作　　者：张兵[1] 孙传智[1] 齐蕾[1] 董林[1] 

机构地区：[1]南京大学化学化工学院,南京210093

出　　处：《无机化学学报》2011年第9期1798-1804,共7页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.20873060;No.20973091);973国家重点基础研究发展计划(No.2010CB732302)资助项目

摘　　要：采用氨水反滴加沉淀法合成了Zr4+掺杂的系列TiO2载体,以尿素溶液为沉淀剂,用沉积-沉淀法制备负载金催化剂。运用N2吸附-脱附(BET)、X射线衍射(XRD)、X射线荧光(XRF)、高分辨电镜(HR-TEM)和氨吸附红外光谱(NH3-IR)等技术对催化剂的结构与形貌进行了表征,并在色谱-微反应装置上考察了催化剂对CO氧化反应的活性。结果表明:(1)少量的Zr4+掺杂可形成锐钛矿型固溶体,且载体的比表面积增大;随着Zr4+掺杂量增加至10%以上,载体逐渐向无定形转变,同时比表面积急剧增大。(2)保持规整锐钛矿晶相的Zr4+掺杂载体,其表面Lewis酸位占有率较高,且具备结构缺陷,而无定形载体表面的Lewis酸位占有率大幅度降低。(3)载体表面的Lewis酸位以及结构缺陷有利于增强载体对Au颗粒的锚定作用,从而减弱焙烧过程中的颗粒聚集。(4)少量Zr4+掺杂入TiO2载体中,可以提高Au颗粒的抗烧结能力,焙烧所得的Au颗粒尺寸较小(3.63 nm),且表现出优异的催化活性,在常温下就可以将CO完全氧化。A family of Zr4＋ doped TiO2 samples （denoted as TixZr1-xO2） were prepared by addition of Zr4＋ and Ti4＋ precursors into ammonia solution and used as supports to obtain Au catalysts via deposition-precipitation with urea. The catalysts were characterized by N2-adsorption, XRD, XRF, HR-TEM and NH3-IR techniques, and their catalytic performance over CO oxidation was also evaluated. The results indicate： （1） Anatase titania-zirconia solid solutions with larger surface area could be formed by doping a small amount of Zr4＋, while amorphous structures appear when doping amount increases to more than 10%. （2） The ratio of Lewis acid site of the catalysts is determined by the nature of supports, i.e., amorphous and crystalline supports produce small and large ratio of Lewis acid site, respectively. （3） The particle size of Au is mainly influenced by the properties of the support. For supports with more structure defects and larger ratio of Lewis acid site, the growth and migration of Au particles are suppressed and small Au particles are obtained. （4） The doping of a small amount of Zr4＋ effectively inhibits the sintering of Au, thus making the catalyst shown a good activity in CO oxidation with full conversion of CO at room temperature.

关 键 词：负载金催化剂 二氧化钛 掺杂 Zr4+ CO氧化反应 Au颗粒尺寸 

分 类 号：O614.123[理学—无机化学] O614.411[理学—化学]