Structure design of CeO2–MoS2 composites and their efficient activity for imine synthesis

Abstract

Imines are important compounds in organic chemistry and polymer chemistry. Nanoflaked CeO 2 -MoS 2 composites, used as the catalyst in the imine synthesis, were synthesized by solvothermal method using calcined CeO 2 nanoflakes as substrate. XPS confirmed that the CeO 2 -MoS 2 (1:2) had the higher Ce 3+ % and the lower Mo 6+ % than the pure CeO 2 or pure MoS 2 , which benefitted the catalytic activity. Meanwhile, the imine conversion proved the excellent catalytic ability of CeO 2 -MoS 2 (1:2), better than pure CeO 2 or MoS 2 . This might be attributed to the heterogeneous junction formed between CeO 2 and MoS 2 , which caused faster Ce 4+ /Ce 3+ transformation (more O*generation) and extra H 2 O consumption.

CeO2 Structure Adjustment by H2O via the Microwave–Ultrasonic Method and Its Application in Imine Catalysis

“…The reaction rates of all the samples were far better than the 0.46 mmol g −1 h −1 reported in Angew ( Tamura and Tomishige, 2015 ). It has been reported earlier that CeO 2 can be used as an easily separable catalyst for imine synthesis at low temperature (<100°C) ( Zhang et al, 2017 ; Zhang et al, 2018 ; Chen et al, 2020 ; Wu et al, 2021 ) and oxygen vacancies (Ce 3+ defects) played an important role during this reaction. The Ce 3+ vacancies can promote the transition of benzyl alcohol to benzaldehyde, and the latter can easily couple with aniline to form an imine compound ( Tamura and Tomishige, 2015 ; Zhang et al, 2017 ; Qin et al, 2019 ).…”