Controlled oxidation state of Ti in MgO-TiO₂ composite for CO₂ capture

다국어 초록 (Multilingual Abstract)

Mesoporous MgO-TiO<SUB>2</SUB> sorbents denoted as (xMgO-TiO<SUB>2</SUB>) with different Mg/Ti molar ratios were synthesized by single step evaporation-induced self-assemble (EISA) method for its application to CO<SUB>2</SUB> capture. The effect of Mg/Ti molar ratio of mesoporous MgO-TiO<SUB>2</SUB> sorbents on their physicochemical properties, oxidation state of titanium, and CO<SUB>2</SUB> adsorption performance was investigated. The phase of xMgO-TiO<SUB>2</SUB> was transformed in the sequence of MgTiO<SUB>3</SUB> (Mg/Ti=1.0 and 2.0)→MgO-MgTi<SUB>2</SUB>O<SUB>4</SUB> (Mg/Ti=3.0 and 4.0)→MgO-Mg<SUB>2</SUB>TiO<SUB>4</SUB> (Mg/Ti=5.0). However, with the increasing Mg/Ti molar ratio, CO<SUB>2</SUB> adsorption performance increased in the order of MgTiO<SUB>3</SUB><MgO-MgTi<SUB>2</SUB>O<SUB>4</SUB><MgO-Mg<SUB>2</SUB>TiO<SUB>4</SUB>. Among the sorbents tested 3.0MgO-TiO<SUB>2</SUB> showed the best CO<SUB>2</SUB> adsorption performance corresponding to ~1mmol/g (4.39wt.%). It was observed that the MgTi<SUB>2</SUB>O<SUB>4</SUB> (Ti<SUP>3+</SUP>-O-Mg<SUP>2+</SUP>) could create highly basic sites compared to MgTiO<SUB>3</SUB> and Mg<SUB>2</SUB>TiO<SUB>4</SUB>. In the process of CO<SUB>2</SUB> adsorption, high surface area (111.4m<SUP>2</SUP>/g), large pore volume (0.45cm<SUP>3</SUP>/g) as well as appropriate basic sites of Mg-O-Ti make it a plausible candidate for CO<SUB>2</SUB> adsorption.