Au3+ Species Boost the Catalytic Performance of Au/ZnO for the Semi-hydrogenation of Acetylene

Huiran Zhou; Bingxin Li; Yanxing Zhang; Xinyu Yan; Wenxin Lv; Xiaobing Wang; Bingbing Yuan; Yang Liu; Zongxian Yang; Xiangdong Lou

doi:10.1021/acsami.1c02723

Au³⁺ Species Boost the Catalytic Performance of Au/ZnO for the Semi-hydrogenation of Acetylene

ACS Appl Mater Interfaces. 2021 Sep 1;13(34):40429-40440. doi: 10.1021/acsami.1c02723. Epub 2021 Aug 24.

Authors

Huiran Zhou¹, Bingxin Li^{1

2}, Yanxing Zhang³, Xinyu Yan¹, Wenxin Lv¹, Xiaobing Wang¹, Bingbing Yuan¹, Yang Liu¹, Zongxian Yang³, Xiangdong Lou¹

Affiliations

¹ Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China.
² Luoyang Refinery Hongda Industrial Co., Ltd., Luoyang, Henan 471012, China.
³ School of Physics, Henan Normal University, Xinxiang, Henan 453007, China.

PMID: 34425673
DOI: 10.1021/acsami.1c02723

Abstract

Au nanoparticles have garnered remarkable attention in the chemoselective hydrogenation due to their extraordinary selectivity. However, the activity is far from satisfactory. Knowledge of the structure-performance relationship is a key prerequisite for rational designing of highly efficient Au-based hydrogenation catalysts. Herein, diverse Au sites were created through engineering their interactions with supports, specifically via adjusting the support morphology, that is, flower-like ZnO (ZnO-F) and disc-like ZnO (ZnO-D), and the catalyst pretreatment atmosphere, that is, 10 vol % O₂/Ar and 10 vol % H₂/Ar (denoted as -O and -H, respectively). The four samples of Au/ZnO were characterized by various techniques and evaluated in the semi-hydrogenation of acetylene. The transmission electron microscopy results indicated that the Au particle sizes are almost similar for our Au/ZnO catalysts. The charge states of Au species demonstrated by X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy with CO as the probe molecule, and simulation based on density functional theory, however, are greatly dependent on the ZnO shape and pretreatment atmosphere, that is, the percentage of Au³⁺ reduces following the order of Au/ZnO-F-O > Au/ZnO-F-H > Au/ZnO-D-O > Au/ZnO-D-H. The testing results showed that the Au/ZnO-F-O catalyst containing maximum of Au³⁺ possesses the optimal activity with 1.8 × 10^-2 s^-1 of specific activity at 200 °C, around 16.5-fold of that for Au/ZnO-D-H. More interestingly, the specific rate at 200 °C and the average conversion/selectivity in the entire operating temperature range are well correlated with the redox states of the Au species, indicating that Au³⁺ sites are more active for acetylene hydrogenation. A plausible explanation is that the Au³⁺ species not only facilitate acetylene adsorption via electrostatic interactions but also favor the heterolysis of H₂ via constructing frustrated Lewis pairs with O.

Keywords: Au3+; acetylene semi-hydrogenation; heterogeneous catalysis; support morphology; supported metal catalyst.