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

Nanostructured MgO sorbents show promise for intermediate-temperature CO 2 capture from post-combustion flue gas stream. However, their CO 2 capture behaviors can be affected by the magnesium precursors applied for sorbent synthesis. To screen potential precursors for fabricating excellent CO 2 trappers, MgO nanoparticles (NPs) were synthesized by calcining several organometallic precursors, including magnesium ethoxide, magnesium acetate tetrahydrate, magnesium oxalate dehydrate, magnesium lactate dihydrate, magnesium citrate nonahydrate, and magnesium gluconate hydrate. The precursors and MgO NPs were characterized by thermogravimetric analysis, X-ray diffraction, N 2 adsorption–desorption, field emission scanning electron microscopy, and CO 2 temperature-programmed desorption. A fixed-bed reactor was used to evaluate the CO 2 capture performances of the MgO NPs in a simulated flue gas stream. The effect of organometallic precursors on CO 2 capture behaviors of the sorbents was further demonstrated. Results indicated that the different precursors would yield MgO NPs with distinct textural and surface properties, and these could further affect their CO 2 capture behaviors. MgO NPs derived from magnesium oxalate dehydrate exhibited the highest CO 2 uptake of 4.41 mmol of CO 2 /g. The excellent CO 2 uptake was mainly attributed to its superlative textural properties, uniform surface morphology, and abundant base sites.