基于烟气条件的改性分子筛吸附CO_(2)研究

Research on Adsorption of CO_(2) by Modified Molecular Sieve Based on Flue Gas Conditions

碳捕集是主要的“近零碳”能源技术,对雄安新区建设绿色低碳之城有重要意义。吸附法是目前最有前景的CO_(2)捕集技术之一。为获得稳定的吸附材料,对比了5种分子筛的微观结构和吸附性能,筛选了5A型分子筛作为改性基体,探索了多种碱金属离子改性对CO_(2)吸附容量的影响。结果表明,分子筛均具有较高的比表面积和有利于CO_(2)吸收的微孔与介孔结构;5A型分子筛的吸附容量最高,且因水蒸气与CO_(2)竞争活性点位会抑制CO_(2)的吸收;与K、Na、Li等离子相比,采用Zn离子改性可以增加碱性和孔内吸附势,将CO_(2)的吸附容量由9.61%增至12.02%。Zn改性5A型分子筛在含湿量低于8%条件下,形成的碳酸锌水合物会产生新的吸附点位,促进吸附容量随着含湿量的增加而升高,且多次吸脱附循环稳定性良好,表现出一定的应用潜力。

Carbon capture is a major "near-zero carbon" energy technology, which is of great significance to the construction of green and low-carbon city in Xiongan New Area.Adsorption method is currently one of the most promising technologies for CO_(2) capture.In order to obtain stable adsorption material, the microstructure and adsorption performance of five kinds of molecular sieve were studied, molecular sieves 5A was selected as modified matrix, and the influence of alkali metal ions modification on adsorption capacity of CO_(2) was explored.The results showed that molecular sieves have higher specific surface area and better CO_(2) adsorption with microporous and mesoporous structures.The adsorption capacity of molecular sieves 5A was the highest, and the CO_(2) adsorption was reduced due to the competition of water vapour with CO_(2) on active site.Compared with K,Na, Li ions, the modification of Zn ions could increase the alkaline and pore adsorption potential, and increase the adsorption capacity of CO_(2) from 9.61% to 12.02%.When the moisture content of Zn-modified 5A molecular sieve was lower than 8%,the zinc carbonate hydrate formed would produce new adsorption site, which would promote the increase of adsorption capacity with the increasing of moisture content.Moreover, the adsorption capacity of the Zn-modified 5A molecular under multiple absorption-desorption cycle reached great stability, which endowed the material with certain application potential.