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 m²/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.

paper information

Journal of CO2 Utilization  Volume 42, December 2020, 101294

Received 18 May 2020, Revised 29 July 2020, Accepted 18 August 2020, Available online 31 August 2020.

Authors:  Vishwanath Hiremath, Bezawit Tatek Shiferraw, Jeong Gil Seo

DOI : https://doi.org/10.1016/j.jcou.2020.101294