MgO insertion endowed strong basicity in mesoporous alumina framework and improved CO₂ sorption capacity

Abstract

Fine tuning the electronic properties of amorphous mesoporous alumina has been extensively studied due to its wide range of applications. Luckily, fundamental changes via secondary metal atom insertion has been broadly recognized and pave the way towards development of novel materials. In this study, structure-property correlation of mesoporous alumina framework has been evaluated for elevated temperature application via MgO insertion. The pristine Al2O3 possess an excellent specific surface area corresponding to 319 m2/g with average pore diameter of 14.8 nm. However, surface area and pore diameter were linearly decreased as a function of hydrothermal temperature. Remarkably, MgO insertion improved its specific surface area to 357 m(2)/g with narrow pore size distribution at 7.1 nm. The improved surface area is due to the coexistence of MgO with Al2O3 in its amorphous framework. Meanwhile, the improved CO2 sorption capacity attributed to the induced strong basic sites via MgO insertion and better kinetics is due to the appropriate pore structure of the derived nano composite. Further, the heterogeneity of the alumina framework with 6-coordinated and 4-coordinated environment established improved basicity as suggested by solid state 27Al-NMR and CO2-TPD results. The developed composite shows excellent thermal stability for temperature swing CO2 desorption with 95% retainment in its sorption capacity.