碱金属碳酸盐吸收燃煤电厂烟气中的CO2及其再生的机理研究

It is focused on CO2 emission reduction for the attention from the international community. Large amounts of CO2 in flue gas from coal-fired power plant, can be captured by using the alkali metal-based (Na2CO3, K2CO3) absorbents through gas-solid reaction. However, the serious shortcomings exist, such as the unclear mechanism because of complicated structure of the adsorbents, the higher regeneration energy consumption and so on. Therefore, the efficient and suitable adsorbents of CO2 is the key of CO2 emission reduction. In this work, the density functional theory (DFT) methods, combined with experimental preparation as well as XRD, XPS, IR, SEM and ICP-AES techniques, will be used to build a series of models of CO2 adsorbents about alkali metal carbonate, to clarify the interaction between alkali metal carbonates and supports as well as the effect of the interactions on the capture of CO2. Further, to explore the mechanism of sorbent carbonation and adsorbents regeneration. On the bases of coupling of the mechanisms of capture and regeneration, it is analyzed for the internal factors to sorbent carbonation and regeneration, further, the theoretical clue will be provided for modifying the alkali metal-based CO2 adsorbents.

CO2的减排是国际社会关注的热点。燃煤电厂排放出的烟气中含有大量的CO2，可以利用碱金属碳酸盐（Na2CO3，K2CO3）作为吸收剂，通过气-固反应脱除。然而，该类吸收剂存在结构复杂使得反应机理不清晰，吸收剂再生能耗过高等缺点。因此，使用高效适宜的CO2吸收剂是减排CO2的关键问题。该项目拟利用密度泛函理论结合实验制备和XRD，XPS，IR，SEM以及ICP-AES等表征手段建立一系列吸收CO2的碱金属碳酸盐吸收剂的模型，在电子水平上阐明碱金属碳酸盐和载体之间相互作用以及这种相互作用对CO2吸收的影响，探讨吸收剂碳酸化的微观反应机理以及吸收剂的再生机理。耦合吸收和再生反应机理，分析影响吸收剂碳酸化和再生的内在原因，为CO2吸收剂的改性提供理论线索。

用碱金属碳酸盐M2CO3(M=K,Na)作为吸收剂进行燃烧后捕获CO2，具有原料廉价易得，反应所需温度温和等优点。但是M2CO3与CO2反应速率慢，CO2脱除效果较差，这些缺点严重阻碍了该吸收剂的工业应用。本项目通过量子化学计算方法，在电子-原子水平上系统地研究了单斜和六方晶型的共13种K2CO3低指数晶面以及活性炭、CaO、MgO、Fe2O3、V2O3、Al2O3和TiO2等载体负载的K2CO3吸收剂捕获CO2的微观机理和吸收剂的再生机理，筛选出（1）六方K2CO3（010）面作为吸收剂的活性组分具有高效捕获CO2的性能（2）V2O3，Fe2O3，金红石作为载体的吸收剂具有高效捕获CO2的性能和好的再生性能（3）CaO、MgO和Al2O3由于生成的副产物再生困难而不推荐作为吸收剂载体，提出了加入助剂用以提高OH的生成速率或者提高CO2的覆盖度来提高吸收剂效率的理论线索。.通过本项目的研究，我们培养出硕士生1名，在SCI收录的期刊发表了论文7篇，获得授权专利1项，在9届国际分子模拟会议上作口头邀请报告1次。