载体相变下Pt-TiO_(2) SMSI研究及其对CO催化性能的影响  

The SMSI of Pt-TiO_(2) During the Crystalline Phase Transformation and Its Effect on CO Oxidation Performance

作　　者：贾亚辉 李春生[1] 徐忠震 刘伟 高道伟 陈国柱[1] Jia Yahui;Li Chunsheng;Xu Zhongzhen;Liu Wei;Gao Daowei;Chen Guozhu(School of Chemistry and Chemical Engineering,University of Jinan,Jinan 255022,China;b School of Water Conservancy and Environment,University of Jinan,Jinan 250002,China)

机构地区：[1]济南大学化学化工学院,济南255022 [2]济南大学水利与环境学院,济南250002

出　　处：《化学学报》2022年第9期1289-1298,共10页Acta Chimica Sinica

基　　金：国家自然科学基金(No.21878121);山东省自然科学基金(No.ZR202102230042)资助。

摘　　要：金属-载体强相互作用(SMSI)是多相催化中的一个重要概念,对负载金属催化剂的稳定性和活性均有重要影响.目前尽管有关Pt-TiO_(2)体系的SMSI已有阐述,但主要围绕载体的结构敏感性(晶面效应)、贵金属的粒径尺寸(尺寸效应)对SMSI的影响进行研究,而TiO_(2)的晶型对SMSI的形成是否存在影响目前尚未报道.在本工作中,选择青铜矿TiO_(2)(B)为载体,通过浸渍法负载Pt得到Pt-TiO_(2)(B)催化剂,并在H_(2)、H_(2)-O_(2)氛围对其进行热处理.研究结果表明,500℃高温下H2处理不仅导致催化剂中载体由青铜矿变为锐钛矿,而且引起载体迁移至Pt颗粒表面形成几何包覆.当此催化剂再次经400℃O_(2)处理,Pt颗粒表面的包覆层消失,呈现典型的SMSI行为.借助高分辨透射电子显微镜(HRTEM)以及CO漫反射傅立叶变换红外光谱(CO-DRIFTS)结果分析,TiO_(2)的晶型转变对SMSI的形成具有重要影响.此外,对不同气氛、温度下处理的Pt-TiO_(2)进行了催化CO氧化性能研究,结果证明SMSI产生的几何包覆以及载体的氧缺陷对催化CO氧化性能提升发挥了重要作用.显然,该工作丰富了Pt-TiO_(2)体系的SMSI研究,为其它载体晶相转变(或物相转变)可能诱导SMSI产生提供了参考意义.The strong metal-support interaction(SMSI)has long been studied in heterogonous catalysis on account of its importance in stabilizing active metals and tuning catalytic performance.So far,although there are many reports about SMSI in Pt-TiO_(2) system,they are mainly focusing on support structure sensitivity(crystal plane effect)and the size of supported noble metals(size effect),it is still unclear whether the TiO_(2) crystalline phase influences the creation of SMSI or not.In this study,we choose brookite TiO_(2)(TiO_(2)(B))as support to prepare Pt-TiO_(2)(B)catalyst by means of traditional impregnation method.Then the as-prepared Pt_(imp)/TiO_(2)(B)was treated at different temperature under different atmosphere,specifically,250℃ heat treatment under H_(2)(the sample is labeled as Pt_(imp)/TiO_(2)(B)-H250),500℃ heat treatment under H_(2)(the sample is labeled as Pt_(imp)/TiO_(2)(B)-H500),and 400℃ heat treatment under O_(2) followed by H_(2) treatment at 500℃(the sample is labeled as Pt_(imp)/TiO_(2)(B)-H500+O400).The experimental results show that the 500℃ heat treatment under H_(2) atmosphere induces the crystalline phase transformation of TiO_(2)(B)into anatase,and more importantly,this transformation leads to the TiO_(2)-x migration as a result of the encapsulation of Pt particles by TiO_(2-x).After further heat treatment at 400℃ under O_(2) atmosphere,the TiO_(2-x) shell coated on the Pt nanoparticle surfaces was removed,which displays a classical SMSI behavior.According to the high resolution transmission electron microscope(HRTEM)and CO diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS)results,we proposed that the crystalline phase transformation plays a great role in the creation of SMSI.In addition,we selected CO oxidation as a model reaction to compare the catalytic activity of Pt_(imp)/TiO_(2)(B)catalysts.The results demonstrate that the activity of the catalysts is simultaneously affected by the TiO_(2-x) coating on Pt na-noparticles and the oxygen vacancy concentratio

关 键 词：金属-载体强相互作用 青铜矿 晶相转变 几何包覆 CO氧化 

分 类 号：O643.36[理学—物理化学]