Efficient Activation of CO2 over Ce-MOF-derived CeO2 for the Synthesis of Cyclic Urea, Urethane, and Carbamate

Abstract

The synthesis of various commodity chemicals like cyclic urea, urethanes, and carbamates via effective utilization of CO2 has proved to be highly advantageous. Production of the chemicals mentioned above from CO2 requires a complicated catalyst design and stringent reaction conditions. A simple catalyst possessing suitable sites that can effectively adsorb and activate CO2 is required to synthesize these valuable chemicals. The catalyst should also have optimum acidity for amine adsorption to facilitate these reactions. This study demonstrates the synthesis of a highly efficient catalyst, Ce-BTC MOF-derived CeO2, for CO2 activation. Ce-BTC-MOF is synthesized and calcined to obtain Ce-BTC MOF-derived CeO2. The presence of various facets and the oxygen vacancy required for CO2 activation and adsorption is confirmed using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). CO2 adsorption efficiency is evaluated using the adsorption experiments. The acidity and basicity of the catalyst are evaluated using the temperature-programmed desorption (TPD) analysis. Cyclic urea is produced by the reaction of diamine and CO2 at low CO2 pressure, while the CO2 and amino alcohol reaction produce cyclic urethane. The reaction between CO2 and primary amine produces carbamate. The calcination of Ce-BTC MOF at 573 K generates a CeO2 catalyst, which offers an excellent activity for producing these chemicals. Ce-BTC MOF-derived CeO2 exhibits efficient recyclability and stability. The developed ecofriendly and robust catalyst will be of significant scientific interest because it can be industrially deployed in producing these commercial synthetic intermediates.