Asymmetric Sites on the ZnZrO x Catalyst for Promoting Formate Formation and Transformation in CO2 Hydrogenation

Zhendong Feng; Chizhou Tang; Pengfei Zhang; Kun Li; Guanna Li; Jijie Wang; Zhaochi Feng; Can Li

doi:10.1021/jacs.3c02248

Asymmetric Sites on the ZnZrO _x Catalyst for Promoting Formate Formation and Transformation in CO₂ Hydrogenation

J Am Chem Soc. 2023 Jun 14;145(23):12663-12672. doi: 10.1021/jacs.3c02248. Epub 2023 Jun 1.

Authors

Zhendong Feng^{1

2}, Chizhou Tang^{1

2}, Pengfei Zhang¹, Kun Li¹, Guanna Li³, Jijie Wang¹, Zhaochi Feng¹, Can Li^{1

2}

Affiliations

¹ State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Catalysis Engineering, Department of Chemical Engineering, Delft University of Technology, Van Oder Massage 9, 2629 HZ Delft, Netherlands.

PMID: 37261391
DOI: 10.1021/jacs.3c02248

Abstract

The role of formate species for CO₂ hydrogenation is still under debate. Although formate has been frequently observed and commonly proposed as the possible intermediate, there is no definite evidence for the reaction of formate species for methanol production. Here, formate formation and conversion over the ZnZrO_x solid solution catalyst are investigated by in situ/operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectroscopy (DRIFTS-MS) coupled with density functional theory (DFT) calculations. Spectroscopic results show that bidentate carbonate formed from CO₂ adsorption is hydrogenated to formate on Zn-O-Zr sites (asymmetric sites), where the Zn site is responsible for H₂ activation and the Zr site is beneficial for the stabilization of reaction intermediates. The asymmetric Zn-O-Zr sites with adjacent and inequivalent features on the ZnZrO_x catalyst promote not only formate formation but also its transformation. Both theoretical and experimental results demonstrate that the origin of the excellent performance of the ZnZrO_x catalyst for methanol formation is associated with the H₂ heterolytic cleavage promoted by the asymmetric Zn and Zr sites.