MnO_(x)/Rh(111)模型表面的制备及其CO加氢催化性能研究  

Preparation of MnO_(x)/Rh(111)model surfaces and their catalytic performances for CO hydrogenation

作　　者：马靖凯 李幻[1] 陈明树[1] MA Jingkai;LI Huan;CHEN Mingshu(State Key Laboratory of Physical Chemistry of Solid Surfaces,National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学化学化工学院,固体表面物理化学国家重点实验室,醇醚酯化工清洁生产国家工程实验室,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2023年第1期61-67,共7页Journal of Xiamen University：Natural Science

基　　金：国家自然科学基金(21872110);科技部重大研究计划(2020YFB0606401)。

摘　　要：金属-氧化物载体界面在多相催化中起着至关重要的作用.本研究制备了MnO_(x)/Rh(111)模型表面,采用原位镜面反射红外吸收光谱(IRAS)、扫描隧道显微镜(STM)、俄歇电子能谱(AES)和低能电子衍射(LEED)对其进行表征,并考察其在真空高温退火处理下的稳定性和CO加氢催化性能.结果显示:在Rh(111)单晶上沉积了规整有序且热稳定性好的不同覆盖度的MnO_(x)薄膜,MnO_(x)在Rh(111)上逐层生长,并在亚单层时形成清晰的二维团簇;低覆盖度时MnO_(x)二维簇以MnO的形式优先生长在Rh(111)的台阶位,并大多呈三角形,在亚单层Rh-MnO_(x)界面周边估测的长度随MnO_(x)覆盖度呈火山型变化,在0.4~0.5 ML(单层)之间有最大值.Rh(111)表面上CO加氢反应主要生成甲烷,部分覆盖MnO_(x)后显著抑制甲烷的生成而乙醇的选择性显著提高,且MnO_(x)盖满单层以后表面的催化活性下降.这些结果表明Rh-MnO_(x)界面位点可能是CO加氢生成乙醇的活性中心.Metal-oxide support interface plays a crucial role in heterogeneous catalysis.In this study,MnO_(x)/Rh(111)model surfaces were prepared and characterized by in-situ infrared reflection adsorption spectroscopy(IRAS),scanning tunneling microscope(STM),Auger electron spectroscopy(AES),and low energy electron diffraction(LEED).Stability of the MnO_(x)/Rh(111)model surfaces was examined under high vacuum annealing at high temperature.Catalytic performances of MnO_(x)/Rh(111)model surfaces for CO hydrogenation to ethanol was tested.The results showed that MnO_(x)thin films with different coverages were deposited on Rh(111)single crystals,which were well ordered and had good thermal stability.MnO_(x)grew layer-by-layer on Rh(111)and formed well defined two-dimensional clusters at submonolayer.The two-dimensional clusters of MnO_(x),mostly with a triangle shape,grew preferentially on the step sites of the Rh(111)surface in the form of MnO at low coverage.The perimeter of the Rh-MnO_(x)interface boundary at submonolayer as a function of the MnO_(x)coverage presented as volcano shape,with the maximum value occuring at 0.4-0.5 ML(single layer).The hydrogenation reaction of CO on the clean Rh(111)formed mainly CH_(4),which was significantly inhibited by partial coverage of MnO_(x).The selectivity of ethanol was significantly higher on the MnO_(x)/Rh(111)than on the Rh(111).The fully covered MnO_(x)/Rh(111)was less active for CO hydrogenation than the Rh surface.These results suggested that the site of the Rh-MnO_(x)interface might be the specific active center for CO hydrogenation to ethanol.

关 键 词：MnO_(x)/Rh(111) 金属-氧化物界面 反射红外吸收光谱 扫描隧道显微镜 CO加氢 

分 类 号：O643[理学—物理化学]