Au/SBA-15表面位点的红外光谱表征  

DRIFTS Characterization of Charge State of Surface Site in Au/SBA-15

作　　者：冯晓庆 梁金虎 肖超[2] FENG Xiao-qing;LIANG Jin-hu;XIAO Chao(School of Encironmental and Safery Engineering,North University of China,Taiyuan 030051,China;Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中北大学环境与安全工程学院,山西太原030051 [2]中国工程物理研究院核物理与化学研究所,四川绵阳621900

出　　处：《分子催化》2020年第4期326-333,I0002,共9页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金(11602231,11705176);山西省重点研发计划国际合作项目(201803D421101);中北大学青年学术带头人支持计划(QX201810)。

摘　　要：CO催化氧化反应是多相金催化反应中研究最为广泛的反应体系之一,但对于金表面活性位点之电荷状态(电正性Au^δ+,电中性Au^0,电负性Au^δ-)的理解仍然存在着分歧.选用介孔SBA-15作为载体,阳离子[Au(en)2]^3+为前驱体,通过离子交换法制备了Au/SBA-15催化剂.采用漫反射傅里叶变换红外光谱(DRIFTS)研究了CO探针分子在Au/SBA-15催化剂表面的吸附状态及在不同条件下的演化情况.Au/SBA-15制备过程中的热处理步骤对其吸附CO能力有较大影响.在只经过还原处理的样品上,由于残余的乙二胺配体覆盖了金表面位点,没有吸附CO的能力.需进行还原-焙烧-二次还原处理后,Au/SBA-15才有吸附CO的能力.CO吸附在Au/SBA-15出现两个红外特征吸收峰:2111和2076 cm^-1.它们对应于两种电荷状态的Au位点:Au^0和Au^δ-.CO在Au^0吸附强度比在Au^δ-上更强.而Au^δ-上吸附的CO(CO-Au^δ-)则与O2有更高的反应活性.CO oxidation is one of the most widely studied ones among heterogeneous gold canalized reactions,but there are still inconsistent views on the charge state of the active site(cationic Au^δ+,metallic Au0 or anionic Au^δ-).Herein,Au/SBA-15 catalyst was prepared with[Au(en)2]Cl3 as the precursor.The CO adsorption on Au/SBA-15 catalyst and their evolution under different conditions were investigated by diffuse reflection Fourier transform infrared spectroscopy(DRIFTS).The thermal treatment during the catalyst preparation has great impact on the CO adsorption capacity.On the initially reduced Au/SBA-15,the residual ethylenediamine ligands cover the gold sites which results in no adsorption capacity for CO;but after reduction-calcined-reduction treatment,it gains the ability to adsorb CO.There are actually two sites on Au/SBA-15:Au0 and Au^δ-corresponding to two adsorption peaks in DRIFT spectra:2111 cm^-1(CO-Au0)and 2076 cm^-1(CO-Au^δ-).The CO adsorption on Au0 is stronger than on Au^δ-,whereas the CO adsorbed on Au^δ-has higher reactivity to O2.

关 键 词：金催化剂 CO氧化 原位红外光谱 DRIFTS SBA-15 

分 类 号：O643.32[理学—物理化学]