Development of mesoporous magnesium oxide–alumina composites for CO2 capture

Abstract

Mesoporous magnesium oxide-alumina composites were synthesized by evaporation induced self assembly (EISA) in the presence of triblock copolymer Pluronic P123 in absolute ethanol solution. These mesostuctures were prepared usingAl(NO 3 ) 3 •9H 2 O and Mg(NO 3 ) 2 .6H 2 O as alumina and MgO precursors, respectively. Block copolymer was completely removed by thermal treatment of as-synthesized samples at 350 o C in flowing nitrogen. Thermally treated composites displayed relativelyhigh specific surface area and large pore volume. Temperature programmed desorption (TPD) was used to investigate the active sites available on the surface of the aforementioned samples for CO 2 sorption at 120 o C. Magnesium oxide-alumina composite samples showed an enhanced CO 2 uptake under flue gas conditions (100~150 o C). The sample synthesized from Al(NO 3 ) 3 •9H 2 O) only showed adsorption capacity of about 1.30 mmol/g.Incorporation of 10 molar % of MgO did not significantly increase the CO 2 uptake of the alumina-based composite; however, incorporation of 30 molar % of MgO increased CO 2 uptake up to 2.08 mmol/g. An increase of the MgO content in the composite caused a gradual enhancement in the CO 2 uptake; namely, the composite with 70 % of MgO loading showed 2.87 mmol/g CO 2 uptake. High thermal and mechanical stability of the composites studied as well as their low cost, good resistance to the corrosion and oxidizing environment make these materials, especially MgO-rich composites, attractive candidates for CO 2 capture at flue gas conditions.

Ordered Mesoporous Alumina and Their Composites Based on Evaporation Induced Self-Assembly for Adsorption and Catalysis

“…Incorporating basic species like MgO into OMA is effective for strengthening the interaction with acidic CO 2 . 122 Hence, with the MgO content increasing, MgO-Al 2 O 3 composite oxides displayed enhanced CO 2 uptake from 1.30 to 2.87 mmol/g. A dual-templated MgO-Al 2 O 3 composite was also designed for CO 2 adsorption via the EISA route using P123 and ionic liquid as templates.…”

“…The basicity of adsorbents has a significant influence on CO 2 adsorption performance. Incorporating basic species like MgO into OMA is effective for strengthening the interaction with acidic CO 2 . Hence, with the MgO content increasing, MgO-Al 2 O 3 composite oxides displayed enhanced CO 2 uptake from 1.30 to 2.87 mmol/g.…”

Nanostructured MgO Sorbents Derived from Organometallic Magnesium Precursors for Post-combustion CO2 Capture

“…Precipitation, hydrothermal, and sol−gel methods have been widely adopted to fabricate highly efficient CO 2 sorbents with improved textural properties and controlled surface morphologies. 26,27,29,31 However, these synthesis routes will consume massive costly raw materials and chemical additives. In contrast, the solid-state reaction process could be a facile, economic, and green route for sorbent development.…”

“…Previous work indicated that MgO presented a high theoretical CO 2 capture capacity, while the CO 2 uptake of commercial bulk MgO could be as low as 0.5 mmol of CO 2 /g as a result of the limited base sites. , Besides, the carbonation process of MgO was kinetically controlled, and the reaction rate could be limited by its high lattice energy. , Thus, the principal problem for MgO sorbents is the limited CO 2 uptake and reaction rate. To improve their CO 2 capture performances, attempts, such as optimizing the synthesis methods and fabricating nanosized sorbents doped with alkaline metal eutectic mixtures, have been made to enhance their textural and surface properties and to reduce the activation energy. − One important approach to achieving such goals is to prepare porous MgO sorbents using different magnesium precursors. Precipitation, hydrothermal, and sol–gel methods have been widely adopted to fabricate highly efficient CO 2 sorbents with improved textural properties and controlled surface morphologies. ,,, However, these synthesis routes will consume massive costly raw materials and chemical additives.…”

“…To improve their CO 2 capture performances, attempts, such as optimizing the synthesis methods and fabricating nanosized sorbents doped with alkaline metal eutectic mixtures, have been made to enhance their textural and surface properties and to reduce the activation energy. − One important approach to achieving such goals is to prepare porous MgO sorbents using different magnesium precursors. Precipitation, hydrothermal, and sol–gel methods have been widely adopted to fabricate highly efficient CO 2 sorbents with improved textural properties and controlled surface morphologies. ,,, However, these synthesis routes will consume massive costly raw materials and chemical additives. In contrast, the solid-state reaction process could be a facile, economic, and green route for sorbent development. , Therefore, the direct pyrolysis or calcination of magnesium precursors should be promising for facile preparation of MgO sorbents.…”