Zr-Modified ZnO for the Selective Oxidation of Cinnamaldehyde to Benzaldehyde

Catalysts

Pengju Du¹  Xinling Xie¹  Hongbing Ji¹  Zuzeng Qin¹  Xuan Luo¹  Tongming Su¹ 

[1]School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China

关键词: ZnO;    cinnamaldehyde;    oxidation;    benzaldehyde;    Zr-modified;   

DOI  :  10.3390/catal9090716

来源: DOAJ

【 摘 要 】

ZnO and Zr-modified ZnO were prepared using a precipitation method and used for the selective oxidation of cinnamaldehyde to benzaldehyde in the present study. The results showed that physicochemical properties of ZnO were significantly affected by the calcination temperature, and calcination of ZnO at 400 °C demonstrated the optimum catalytic activity for the selective oxidation of cinnamaldehyde to benzaldehyde. With 0.01 g ZnO calcined at 400 °C for 2 h as a catalyst, 8.0 g ethanol and 2.0 g cinnamaldehyde reacted at an oxygen pressure of 1.0 MPa and 70 °C for 60 min, resulting in benzaldehyde selectivity of 69.2% and cinnamaldehyde conversion of 16.1%. Zr was the optimal modifier for ZnO: when Zr-modified ZnO was used as the catalyst, benzaldehyde selectivity reached 86.2%, and cinnamaldehyde conversion was 17.6%. The X-ray diffractometer and N₂ adsorption−desorption characterization indicated that doping with Zr could reduce the crystallite size of ZnO (101) and increase the specific surface area of the catalyst, which provided more active sites for the reaction. X-ray photoelectron spectrometer results showed that Zr-doping could exchange the electrons with ZnO and reduce the electron density in the outer layer of Zn, which would further affect benzaldehyde selectivity. The results of CO₂ temperature-programmed desorption showed that Zr-modification enhanced the alkalinity of the catalyst surface, which caused the Zr−ZnO catalyst to exhibit higher catalytic activity.

【 授权许可】

Unknown