Li 2 SO 4 doped nano CaO (Li 2 SO 4 @nano CaO) based CO 2 adsorbent has been developed to improve calcination–carbonation durability. Li 2 SO 4 @nano CaO adsorbent was obtained by calcination of Li 2 SO 4 doped nano CaCO 3 that was prepared by a simple wet solution impregnation method. The morphology and microstructural properties of the adsorbent were examined by scanning electron microscopy (SEM) and nitrogen physisorption tests, and its cyclic calcination–carbonation performance was evaluated by thermogravimetric analysis (TGA). The results show that Li 2 SO 4 @nano CaO adsorbent maintains a 51.0% CaO conversion after 11 cycles under the calcination temperature of 750 °C and carbonation temperature of 600 °C with an optimized Li 2 SO 4 content of 3.0–5.0 wt.%. Alternatively, pure nano CaO maintains only a 27.3% conversion at the same conditions. A physical property analysis reveals that the superior performance of Li 2 SO 4 @nano CaO adsorbent is attributed to the pore diameter enlargement and to the increase of macro-pore proportion due to Li 2 SO 4 incorporation. Moreover, the carbonation and calcination rates of Li 2 SO 4 @nano CaO adsorbent are accelerated compared with nano CaO adsorbent, and the complete decomposition temperature is at least 15 °C lower. In comparison with the adsorbent doped with other lithium salts (Li 2 CO 3 and LiCl), Li 2 SO 4 @nano CaO adsorbent possesses the best durability under equivalent doping conditions. Furthermore, the positive linear correlation between the complete decomposition temperature and CaO conversion has been maintained.
Ming-jie Liu,Feng Wei,Xue-mei Yang,Shi-an Dong,Ying-jie Li,Xiao-jun He
Porous graphene-like carbon materials (PGCMs) for supercapacitors were synthesized from petroleum pitch by a nano-CaCO 3 template strategy combined with KOH activation. The PGCMs were characterized by TEM, XPS, Raman spectroscopy and N 2 adsorption. Results show that their specific surface areas are 1542-2305 m 2 ·g −1 , depending on the template/pitch ratio, KOH/pitch ratio and activation temperature. The PGCMs feature interconnected graphene-like carbon layers with abundant small pores. The optimum supercapacitor electrode is produced when the PGCM is synthesized with a template/pitch ratio of 1.5, a KOH/pitch ratio of 1.5 at 850 °C for 1h. It has a specific capacitance of 293 F·g −1 at a current density of 0.05 A·g −1 , an excellent rate capability with a capacitance of 231 F·g −1 at a current density of 20 A·g −1 and an outstanding cycling stability with a 97.4% capacitance retention after 7000 cycles in a 6 M KOH aqueous electrolyte. It also exhibits a high specific capacitance of 267 F·g −1 at a current density of 0.05 A·g −1 , and a high energy density of 148.3 Wh·kg −1 at a power density of 204.2 W·kg −1 in a BMIMPF6 ionic liquid electrolyte. This is a possible method for the synthesis of PGCMs for high-performance supercapacitors.
Li Zhang,Kun-kun Deng,Kai-bo Nie,Cui-ju Wang,Chao Xu,Quan-xin Shi,Yu Liu,Jie Wang
Summary Incorporating graphite/graphene into a Mg alloy matrix is a promising approach for developing lightweight heat dissipation materials. However, carbon material is inherently incompatible with Mg because of their distinctly different surface characteristics, resulting in the challenge of composite fabricating and interface controlling. Herein, a new strategy of in situ interfacial modification was proposed to achieve excellent thermal conductivity and mechanical properties in graphite/Mg composites. A super-nano CaCO 3 interfacial layer was reported in this paper. The detailed interfacial structure, reaction thermodynamics and kinetics, and interface strengthening mechanisms were analyzed and discussed. Several preferential epitaxial relationships of the Mg/CaCO 3 interface were revealed, which are conducive to minimize the interfacial energy, stabilize and strengthen the interface. Moreover, strong ionic bond of graphite/CaCO 3 interface was demonstrated. The strong chemical interface bonding of graphite-Mg via in situ interface modification facilitates both the interfacial cohesion and interfacial thermal conduction, which endows the graphite/Mg composites with superior strength–thermal conductivity synergy.
Falong Wang,Yaqiang Dong,Liang Chang,Yan Pan,Qiang Chi,Mengji Gong,Jiawei Li,Aina He,Xinmin Wang
In this paper, a novel type of nano-CaCO 3 /epoxy nanocomposites insulating layer for the FeSiCr/carbonyl-iron soft magnetic composites (SMCs) has been successfully developed. The novel inorganic/resin nanocomposites can greatly reduce the core loss of the SMCs while maintain other excellent magnetic properties . By optimizing the content of insulating layer, the FeSiCr/carbonyl-iron SMCs exhibits the lowest core loss of 466.5 mW/cm 3 at a maximum magnetic induction of 50 mT and frequency of 100 kHz, which is greatly reduced by 24.2%, compared with the sample only coated by epoxy resin . Meanwhile, the effective permeability and quality factor remains high. In addition, the production process of the novel nano-CaCO 3 /epoxy nanocomposites insulating layer exhibits the advantages of simplicity, convenience and low cost compared with other ceramic coatings (Al 2 O 3 , MgO , SiO 2 , etc.) and surface nitride coatings, which is more suitable for the industrialization of molded inductors, and therefore has a variety of industrial application prospects.
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