| Many serious environmental problems have been triggered with the rapid development of industry. Worldwide concern has been received about how to protect the ecological environment. In this thesis, we aim at solving the problems of environmental protection about CO2 capture at flue gas temperature of power plant, and design a series of new porous solid base materials. We loaded MgO on coconut carbon through wet-impregnation method, and discovered the "self-dispersion" of newly formed carbon; Herefrom, insitu carbon-doped MgO with large surface area is successfully fabricated for CO2 capture at elevated temperature; Based on the "carbon insertion" concept, combining with the principle of isomorphous substitution, solid strong base of MgO-ZnO binary metal oxide was fabricated; Finally, Cu-MgO solid base was synthesized, meanwhile, the shrinkage effect of the volumes of CuO nanoparticles before and after reduction was utilized to increase the exposure of MgO. Furthermore, CO2 adsorption with the existence of other competitors, and volatile nitroamine degradation were applied to evaluate the actual performance of this new material.This thesis consists of the following parts:Firstly, MgO supported coconut shell activated carbon (AC) adsorbent was synthesized through wet-impregnation method. The magnesium acetate precursor was carbonized to produce many mixed particles of MgO and newly-formed carbon. The abundant surface curvature of AC support can prevent the newly-formed carbon particles from being blown away by gas flow, and enable them to leave behind and self-disperse MgO particles. The effects of magnesia precursor, support type and loading amount of MgO on the ability of CO2 capture of these materials were investigated. Besides, considering that CO2 concentration in the flue gas of power plant is varied, and the contact time between adsorbent and CO2 is limited, so that the new technology of instantaneous CO2 adsorption is proposed for the first time to precisely evaluate the application values of these adsorbents. Under the synergy of AC with hierarchical structure, MgO-C(newly-formed carbon) mixed particles can adsorb CO2 at 373 and 423 K efficiently, exceeding common amine-based solid materials.Secondly, the adsorption efficiency of per gram adsorbent is inevitably lowered in the existence of support, and the best solution is support non-use. Thus, we used a convenient strategy with low cost and non-solvent to fabricate MgO material with high surface area. Without using any added support, just utilizing the newly formed carbon during carbonization of magnesium acetate to in-situ insert into the MgO particles formed simultaneously, avoiding MgO aggregations and enhancing exposure of MgO. Effects of magnesium salts, carbonization temperature and contact mode between gas flow and sorbent during preparation process on the structures and properties of these sorbents were explored, to find the optimum synthetic condition. The adsorbent has a surface area of -300 m2 g-1 benefiting from the "carbon insertion" concept, and it can instantaneously adsorb 28 mg g-1 of CO2 at 473 K, meanwhile keeping well recyclability. The "carbon insertion" mode is helpful to synthesize other functional materials with large surface area.Then, utilizing the isomorphous substitution between Mg and Zn to produce additional defect sites on the surface of MgO by ZnO incorporating, combining with "carbon insertion" mode, novel porous solid strong base of MgO-ZnO binary oxides were fabricated. The effects of the ratios of Mg and Zn, along with preparation methods on the structure, morphology and property of this solid base were explored. Photoluminescence, UV-visible diffuse reflection spectra technology and High-resolution transmission electron microscopy proved the interactions among the components in this solid base. According to the temperature-programmed-desorption (TPD) results, the amount of basic sites on MgO-ZnO solid base was more than that on carbon-doped MgO, and its medium-strong basic sites can achieve to 79% of the total amount. The solid base can not only efficiently adsorb CO2 at 473 K, but also can desorb completely at 673 K, displaying a potential application in future.Finally, binary solid base was fabricated utilizing the volume changes of metal oxide nanoparticles before and after reduction. Reduction treatment of CuO-MgO enabled the volumes of CuO nanoparticles to shrinkage, making more active sites of adjacent MgO exposed and contact with CO2. CuO acted as an "anchor", inserting into MgO particles. After gentle reduction treatment, mesoporous structure of the solid base kept stable. During the CO2 adsorption with existence of other competitors, the strong basic sites of this solid base are firstly occupied by these competitors, mirroring the high exposure of strong basic sites. Besides, this complex also has high reactivity in nitrosamine degradation, having the potential to be applied into tobacco-specified catalyst to control nitrosamine pollution. |
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