The Study of MgO and/or ZrO2 Modified Al2O3 for CO2 Adsorption

Abstract

Alumina (Al2O3) is widely used as a sorbent in CO2 adsorption and as a catalyst support in CO2 utilization. For this application, the CO2 adsorption ability is the most important property to be improved. Thus, this work presents the idea to modify the surface of a commercial alumina using an Mg-Zr mixed oxide. With this material, sites for CO2 adsorption can be created by generating oxygen mobility property simultaneously with the basicity. To prove this hypothesis, alumina modified with MgO, ZrO2, or Mg-Zr mixed oxide was prepared by an incipient wetness impregnation. The physicochemical properties of the bare alumina and the alumina modified with MgO, ZrO2, or Mg-Zr mixed oxide were investigated using N2 adsorption-desorption and X-ray diffraction. The achievement of oxygen mobility creation was quantitatively evaluated by O2-temperature programmed desorption measurement. The CO2 adsorption performance with the distribution of basic site strength was determined by CO2-temperature programmed desorption measurements. According to the results, the highest oxygen mobility was found in the alumina modified with Mg-Zr mixed oxide, which is approximately 1.7 times that of the bare alumina. The alumina modified with Mg-Zr mixed oxide showed the highest CO2 capacity by approximately 1.4 times compared to the alumina. It is because the cubic ZrO2 stabilized with MgO provided the number of oxygen vacancy sites that can be filled by oxygen atoms in adsorbed CO2 corresponding to the moderate and strong basic sites.