Yafei Guo,Chang Tan,Jian Sun,Weiling Li,Chuanwen Zhao,Jubing Zhang,Ping Lu
Nanostructured MgO sorbents show promise for intermediate-temperature CO2 capture from post-combustion flue gas stream. However, their CO2 capture behaviors can be affected by the magnesium precursors applied for sorbent synthesis. To screen potential precursors for fabricating excellent CO2 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, N2 adsorption–desorption, field emission scanning electron microscopy, and CO2 temperature-programmed desorption. A fixed-bed reactor was used to evaluate the CO2 capture performances of the MgO NPs in a simulated flue gas stream. The effect of organometallic precursors on CO2 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 CO2 capture behaviors. MgO NPs derived from magnesium oxalate dehydrate exhibited the highest CO2 uptake of 4.41 mmol of CO2/g. The excellent CO2 uptake was mainly attributed to its superlative textural properties, uniform surface morphology, and abundant base sites.
Pengjian Wang,Yan Guo,Di Zhou,Da Li,Lixia Pang,Wenfeng Liu,Jinzhan Su,Zhongqi Shi,Shikuan Sun
High-temperature performance is critical to the dielectric polymer capacitors used in environment electronic and high-power applications. Here, the authors report a composite comprising polyimide (PI) dielectric polymers blended with high-insulation magnesium oxide (MgO) nano-filler that exhibits high breakdown strength, wide temperature range, and low dielectric loss. However, most dielectric polymers possess excellent energy storage properties at room temperature and cannot be used at high temperatures above 100 °C. Polyimide dielectric nanocomposites prepared by in situ polymerization, which are composed of easily prepared MgO fillers, have different morphologies, such as nanoparticles (0D), nanowires (1D), and nanoplates (2D). The experimental results show that the insulation behavior and breakdown strength of polymer composites are closely related to the morphology of MgO fillers, and the rationality of this conclusion is further proved by finite-element simulation results. The polymer composites containing ultra-low content (0.5 vol%) MgO nanosheets produce an ultra-high capacitance performance, that is, the discharge energy density is 4.78 J cm −3 at 150 °C, which is significantly better than the most reported dielectric polymers and nanocomposites.
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