Au/SBA-15 catalyst prepared by ozone treatment and importance of negatively charged gold in CO oxidation by DRIFTS

Xiaoqing Feng; Dan Meng; Yong Yang; Zhaoyi Tan; Jinhu Liang; Chao Xiao

doi:10.1016/j.chemosphere.2020.126274

Au/SBA-15 catalyst prepared by ozone treatment and importance of negatively charged gold in CO oxidation by DRIFTS

Chemosphere. 2020 Jul:250:126274. doi: 10.1016/j.chemosphere.2020.126274. Epub 2020 Feb 20.

Authors

Xiaoqing Feng¹, Dan Meng², Yong Yang², Zhaoyi Tan², Jinhu Liang³, Chao Xiao⁴

Affiliations

¹ Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, PR China; School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, PR China.
² Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, PR China.
³ School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, PR China. Electronic address: jhliang@nuc.edu.cn.
⁴ Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, PR China. Electronic address: xiaochao@caep.cn.

PMID: 32113090
DOI: 10.1016/j.chemosphere.2020.126274

Abstract

There is a lack of consensus on the charge state of active gold species in catalytic CO oxidation reaction. Herein, Au/SBA-15 catalyst was prepared by room temperature ozone treatment. Through diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS), two different gold species, Au⁰ and Au^δ- with CO adsorption at about 2112 cm^-1 and 2077 cm^-1, were observed on Au/SBA-15. In CO oxidation mixture, the 2077 cm^-1 band is completely attenuated while the 2112 cm^-1 band retains some intensity. CO-Au^δ- bonding is weaker than that of CO-Au⁰, but CO-Au^δ- exhibits higher reactivity towards oxygen. Ozone treatment produces AuO_x nanoparticles that is not stable and decomposes to metallic Au gradually. To our best knowledge, this is the first time to identify the presence and importance of Au^δ- species for "inert" SiO₂ supported gold catalyst.

Keywords: CO adsorption; CO oxidation; DRIFTS; Gold catalysis; Oxidation state; Ozone treatment; SBA-15.