Enhanced base-catalyzed activity and structural stability of nitrogen-doped carbon modified MgO-MgFe2O4 magnetic composites as catalysts for transesterification of tributyrin
In this work, nitrogen-doped carbon modified MgO-MgFe2O4 (CN-MgFeO) magnetic composites were synthesized by a facile thermal decomposition of Mg-Fe layered double hydroxide (MgFe-LDH) and cyanamide mixture precursors. A series of comprehensive characterizations including powder X-ray diffraction, transmission electron microscopy, fourier transform infrared of CO2 adsorption, CO2-temperature programmed desorption, and X-Ray photoelectron spectroscopy indicated that the introduction of cyanamide could finely turning surface basicity of resulting CN-MgFeO composites, especially surface strong Lewis basicity. Compared with CN-free MgFeO, as-fabricated CN-MgFeO catalysts showed higher activity in the liquid-phase transesterification of tributyrin with methanol. Specially, the CN-MgFeO composite prepared at the cyanamide/Mg molar ratio of 1.5 in the systhesis mixture gave a highest methylbutyrate yield of 80 % after a reaction for 20 min. The high catalytic performance was attributable to the presence of a large amount of strong Lewis basic sites originating from highly dispersed basic MgO-MgFe2O4 mixed metal oxides and CN component in the composite. What is more, such cost-effective CN-MgFeO catalyst had the advantages of intrinsic magnetic property and excellent structural stability. We expect that they may have potential practical applications in the field of industrial production of biodiesels.