Mg‐Ion Inversion in MgO@MgO−Al2O3 Oxides: The Origin of Basic Sites. Issue 12 (16th May 2019)

• Record Type: Journal Article
• Authors: Hiremath, Vishwanath; Kwon, Hyuk Jae; Jung, In‐Sun; Kwon, Soonchul; Kwon, Sung Hyun; Lee, Seung Geol; Lee, Hyun Chul; Seo, Jeong Gil
• Is Part Of: ChemSusChem. Volume 12:Issue 12(2019)
• Page Start: 2810
• Page End: 2818
• Publication Date: 2019-05-16
• Subjects: carbon capture -- metal oxides -- sorbents -- spinel phases -- structure elucidation; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201900072
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Although MgO−Al2 O3 is well known as having a spinel structure, the inversion of which occurs by exchange of the trivalent (Al 3+ ) and divalent (Mg 2+ ) cations, little analytical study of the degree of inversion has been carried out. This study concerns a simple methodology to identify the inversion by solid‐state NMR spectroscopy, whereby its correlation with the CO2 capture capacity of MgO‐rich MgO@MgO−Al2 O3 spinel structures is verified. Through 27 Al and 25 Mg NMR spectroscopy, temperature‐programmed CO2 desorption, and thermogravimetric analysis, higher inversion is found to occur at low Mg/Al ratios and the inversion is found to decrease as the Mg/Al ratio increases. Moreover, the degree of inversion correlates with CO2 sorption, which is associated with the medium‐strength basic sites induced by formation of the unsaturated O 2− species. These results will open new pathways to exploit defects in complex oxides beyond spinels and their derivatives for desired applications. This demonstration of MgO−Al2 O3 for CO2 sorption can contribute to the design of future CO2 sorbents. Abstract : Turn up the base : A simple methodology to identify the inversion of MgO‐rich MgO@MgO−Al2 O3 spinel structures by solid‐state NMR spectroscopy provides a correlation with their CO2 capture capacity. Through NMR spectroscopy, temperature‐programmed CO2 desorption, and thermogravimetric analysis, higher inversion is found to occur at low Mg/Al ratios and the inversion is found to decrease as the Mg/Al ratio increases.