Enhanced photothermal catalytic activity of CeO2 through Co-modified for the carbonylation of amine with CO2

Abstract

The photothermal catalytic carbonylation of n-alkylamine with CO₂ is one of the most promising “carbon neutral” pathways due to the coupling of CO₂ capture and conversion. And the development of high-performance catalysts is vital to the reaction due to the inherent chemical inertness of CO₂. Herein, Co-Ce composite oxides with rich oxygen vacancy (O_v) were successfully synthesized via hydrothermal method and applied firstly to photothermal catalytic carbonylation of n-butyl amine with CO₂. As optimizing the molar ratio of Co₃O₄/CeO₂, Co₃O₄/CeO₂-0.4 with up to both 95.51 % of n-butylamine conversion and 94.50 % of N,N′-dibutylurea were obtained in the presence of PEG 400 solvent using 500 W Xe lamp as the light source under 110 ℃ and 1.0 MPa for 4 h, respectively. Further characterizations such as XRD, BET, Raman, XPS, CO₂/NH₃-TPD, UV–Vis, PL and TPC show that both the high photocurrent density and O_v-rich content on the surface of Co₃O₄/CeO₂-0.4 enhances the adsorption-activation of CO₂ by facilitating the migration of d electrons from the active sites to the 2π antibonding orbitals of CO₂. Finally, a Lewis acid-base interactions mechanism was also proposed in the photothermal catalytic carbonylation of amine by CO₂ over the Co-Ce complex oxides.