Comparative study of manganese oxides with different oxidation states for catalytic carbonylation of n-butylamine by CO2

The four manganese oxides with different oxidation states (MnO, MnO2, Mn2O3, Mn3O4) was synthesized using the hydrothermal method through adjusting process parameters and feedstock ratio, and their catalytic performances for the carbonylation of n-butylamine by CO2 were also investigated. The results showed that the catalytic activities of manganese oxides with different oxidation states in the catalytic carbonylation of n-butylamine by CO2 follow the order of MnO2 > Mn3O4 > Mn2O3 > MnO, in which MnO2 with the Mn4+ ion exhibited as high as 91.60% yield of N,N'-dibutylurea using polyethylene glycol 400 (PEG 400) as solvent under the reaction conditions of 160 ℃, 4 h, and 5.0 MPa. And then a series of characterization including XRD, XPS, H2-TPR, and CO2/NH3-TPD were performed on the as-synthesized manganese oxides with different oxidation states, indicating that the content of oxygen vacancy on the surface of the manganese oxides with different oxidation states plays a key role in catalytic performances of the carbonylation of n-butylamine with CO2.