【作者】 于淼；

【导师】 贺高红；

【作者基本信息】 大连理工大学 ， 化学工程， 2016， 硕士

【摘要】 CO2作为最主要的温室气体,同时也可以作为碳源加以利用,对其进行高效地分离已经成为环保和能源领域的重要课题之一。膜分离法相比于传统的吸收法,吸附法和低温精馏等方法,具有环境友好,设备及操作费用低,占地面积小,易于与其他过程进行耦合等优点。在这其中,共混膜可以将不同材料的优点结合在同一张膜中,从而得到综合性能更优的C02分离膜。具有质子惰性的杂环阴离子可以与CO2进行可逆结合,对基于此类阴离子的离子液体及盐类溶液的研究表明其可以提高相应材料的C02吸收性能。本文采用溶剂蒸发法,以聚醚共聚酰胺(Pebax 2533)为膜材料,以1,2,4-三氮唑钠(TrizNa)的聚乙二醇200(PEG 200)溶液和TrizNa作为添加剂分别制备了共混膜。采用SEM、FTIR、TGA、DSC等方法对共混膜进行了表征。表征结果表明添加剂被成功的混入膜内,且对共混膜的结构与热性能均有一定的影响。相比于纯Pebax2533膜,在添加了一定量的添加剂之后,共混膜的机械性能受到影响,拉伸强度和断裂伸长率均有一定的降低。这是因为在共混膜成膜过程中,液体添加剂会与膜材料产生分相,而固体添加剂则会因与膜材料相容性不强产生一定的团聚。但当添加剂添加量较低时,共混膜机械性能下降不大,两项参数仍保持在较高水平。为确定PEG 200/TrizNa溶液在共混膜中的添加比例,首先测定了不同PEG 200添加量的Pebax 2533/PEG 200共混膜的C02分离性能。上述共混膜在PEG 200添加量为20 wt.%时性能最优,CO2渗透系数,CO2/N2, CO2/CH4和CO2/H2选择性分别达到191.83barrer,26.47,7.92和4.65。进一步考察了Pebax 2533/PEG 200/TrizNa共混膜的CO2分离性能。当TrizNa浓度占PEG 200质量的15、wt.%时,上述共混膜的CO2综合分离性能最优,CO2渗透系数,CO2/N2, CO2/CH4和CO2/H2选择性分别达到219.55 Barrer,32.33,10.12和6.52。提高操作压力能提高C02的渗透速率和选择性。提高操作温度会提高气体的渗透速率,CO2的选择性会大幅降低。进一步考察了单独添加TrizNa制备的Pebax 2533/TrizNa混合基质膜的C02分离性能。当TrizNa添加量为15wt.%时,上述混合基质膜的CO2分离性能最优,CO2渗透系数,CO2/N2,CO2/CH4和CO2/H2选择性分别达到219.01 Barrer,27.40,8.10和4.80。提高操作压力能提高CO2的渗透速率和选择性。提高操作温度会提高气体的渗透速率CO2的选择性会大幅降低。更多还原

【Abstract】 CO2 is regarded as the major greenhouse gas, and also an important carbon resource, so how to separate CO2 high efficiently has become a primary issue in the field of environmental protection and energy. Compared with traditional separation methods, e.g. absorption, adsorption and cryogenic distillation, membrane separation has its unique advantages, e.g. environmental friendly, low capital and operational cost, small footprint and easy to be coupled with other processes. Among kinds of membranes, blend membrane can combine the advantages of different materials, and result in better overall performance. Aprotic heterocyclic anions (AHAs) can react with CO2 reversibly, and recent research about ionic liquid and salt solution based on these anions demonstrated that AHAs can improve their CO2 absorption performance.In this research, solvent-evaporation method was used to prepare blend membranes with different composition. Poly(ether-b-amide) (Pebax 2533) was chosen as polymer matrix, the polyethylene glycol 200 (PEG 200) solution of sodium 1,2,4-triazole (TrizNa) and TrizNa were chosen as blend additives. SEM, FTIR, TGA, DSC were used to characterize the blend membranes. The results showed that the additives were successfully incorporated into the polymer matrix, and the addition of all additives had certain effects on the structure and thermal properties of the blend membranes.Compared with the pristine Pebax 2533 membrane, after the incorporation of additives, the mechanical properties of the blend membranes were affected, both tensile strength and elongation at break decreased. This is because during the formation of the blend membranes, the liquid additives and solid polymer matrix might generate phase separation, and the solid additives might aggregate in the polymer matrix due to the poor incompatibility. But when the additive loadings were not very high, the mechanical properties of the blend membranes were still on a relatively high level.In order to make sure the appropriate loading of PEG 200/TrizNa in Pebax 2533, the CO2 separation performance of Pebax 2533/PEG 200 blend membranes were studied first. When PEG 200 loading is 20 wt.%, the blend membrane exhibits best performance with CO2 permeability of 191.83 Barrer, and the CO2/N2, CO2/CH4 and CO2/H2 selectivities of 26.47, 7.92 and 4.65, respectively.The CO2 separation performance of Pebax 2533/PEG 200/TrizNa blend membranes were further studied. When TrizNa concentration of the PEG 200/TrizNa soluiton is 15 wt.%, the blend membrane exhibits best performance with CO2 permeability of 219.55 Barrer, and the CO2/N2, CO2/CH4 and CO2/H2 selectivities of 32.33,10.12 and 6.52, respectively. Improving operating pressure can increase CO2 permeability and selectivities. Improving operating temperature can increase gas permeabilities, and CO2 selectivities decrease a lot.The CO2 separation performance of Pebax 2533/TrizNa mixed matrix membranes were further studied. When TrizNa loading is 15 wt.%, the mixed matrix membrane exhibits best performance with CO2 permeability of 219.01 Barrer, and the CO2/N2, CO2/CH4 and CO2/H2 selectivities of 27.40,8.10 and 4.80, respectively. Improving operating pressure can increase CO2 permeability and selectivities. Improving operating temperature can increase gas permeabilities, and CO2 selectivities decrease a lot.更多还原