【作者】 陈建华；

【导师】 刘庆林；

【作者基本信息】 厦门大学 ， 工业催化， 2008， 博士

【摘要】 醋酸是化学工业上需求量最大的基本有机化工原料之一,醋酸-水虽然不形成恒沸物,但是二者的相对挥发度不大,特别是在醋酸的含量高于80wt%时,两者的气.液相组成相近。若用传统的精馏的方法进行分离,将消耗大量的能量,长期以来醋酸-水体系的分离问题一直受到人们的重视。渗透蒸发作为一种新型的分离技术,对于混合物中低含量（小于20wt%）的物质的脱除,在经济上是非常有利的。由于醋酸水溶液的强酸性,常用的脱水材料,如聚乙烯醇、聚丙烯酸、聚碳酸酯、聚丙烯腈和海藻酸钠等,在醋酸脱水时所表现出来的性能都不太理想。基于醋酸脱水的重要的工业意义,本论文首次以耐化学溶剂性能优异的亲油性材料酚酞侧基聚醚酮（PEK-C）为膜材料,通过对其进行改性,制备醋酸渗透蒸发脱水膜。利用X一射线衍射（XRD）、红外光谱（FTIR）、扫描电镜（SEM）和透射电镜（TEM）、差示扫描量热仪（DSC）以及接触角分析等手段对膜的微观形态进行表征,系统研究了膜的溶胀吸附、扩散以及渗透蒸发性能。利用浓硫酸对PEK-C进行磺化改性,有效地提高了膜的亲水性,通过控制磺化度可调节磺化聚芳醚酮（sPEK-C）的亲-憎水平衡,膜在醋酸水溶液中的抗溶胀性能良好。SPEK-C膜的渗透蒸发综合指数随着磺化度的增大而提高,当磺化度为0.75时,达到了极大值。利用该磺化度的膜进行醋酸渗透蒸发脱水,在进料水浓度为10wt%和进料温度为50℃,可得到通量和分离因子分别为248 gm^-2h^-1和103的优良性能。为了提高磺化聚芳醚酮（SPEK-C）的通量,利用对醋酸水溶液具有高通量的聚乙烯醇（PVA）与选择性高的磺化酚酞侧基聚芳醚酮（SPEK-C）共混制备了PVA/SPEK-C共混渗透蒸发膜。SEM测试结果表明PVA和SPEK-C相容性很好,XRD结果表明,膜中高分子链之间的距离随着PVA的含量的增大而增大;研究了PVA的含量对膜的性能的影响,结果表明随着PVA含量的增大,共混膜的通量随之增大,同时分离因子随之有所降低。在PVA的含量为40wt%时,膜的分离指数达到了极大值。当进料水浓度为10wt%和进料温度为50℃,通量和分离因子分别为492 gm^-2h^-1和59.3。利用高亲水性的硅钨酸（STA）(H₄SiW₁₂O₄₀)填充交联PVA/ SPEK-C共混膜,制备了STA/PVA-SPEK-C无机-有机杂化膜,很好地解决了PVA/ SPEK-C膜的"trade-off”现象。渗透蒸发结果表明,通量随着STA含量的增大而增大;而分离因子先是随着STA含量的增大而增大,在STA的含量为12wt%时达到极大值,然后,随着STA的含量的增大而减少。当STA的含量为12wt%时,膜的分离指数达到了极大值。当进料水浓度为10wt%和进料温度为50℃,通量和分离因子分别为597 gm^-2h^-1和70.3。利用PEK-C制备复合膜的支撑层,以戊二醛交联的SPEK-C和STA/PVA-SPEK-C为活性层,制备各种复合膜。研究均质膜与复合膜的渗透蒸发性能之间的差异,结果表明,与均质膜相比,复合膜的性能有了很大的提高。扫描电镜测试表明,利用共溶剂可提高STA-PVA-SPEK-C-GA/PEK-C活性层与支撑层相容性;界面形态对膜的渗透蒸发性能有很大的影响,采用水和二甲亚砜为共溶剂的膜的性能高于单一以二甲亚砜为溶剂的膜的性能。当进料水浓度为10wt%和进料温度为50℃,采用共溶剂的STA-PVA-SPEK-C-GA/PEK-C的膜的通量和分离因子分别为592 gm^-2h^-1和91.2。更多还原

【Abstract】 Acetic acid is one of the most demand products in the chemical industry. Although acetic acid and water mixture is not an azeotropic compound, the relative volatility of water to acetic acid is close to unity. It becomes even more difficult to separate by distillation as the compositions of water in liquid and vapor phase approach almost equal, especially in the region of the acetic acid content being higher than 80 wt%. A conventional dehydration of acetic acid is completed by distillation an energy-consumption skill. So the separation of acetic acid from water is an eye-catcher task. As a novel separation technology, pervaporation （PV） is very economical to remove the component from the mixtures when its content is lower than 20 wt%. The most used hydrophilic membranes, such as Poly（vinyl alcohol）（PVA）, Polyacrylic acid （PAA）, Ployacrylonitrile （PAN） and sodium alginate（NaAlg）, show discouraging separation capability in PV of acetic acid aqueous for its strong acidity. From the dehydration of acetic acid in industry, novel membranes used for this purpose were prepared by modifying Cardo polyetherketone （PEK-C） （which is solvent resistance and hydrophobic） for the first time. The membranes were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FTIR）, Scanning electron microscope （SEM）, Transmission electron microscope （TEM）, Differential Scanning Calorimetry （DSC） and contact angle meter, and their swelling and sorption properties, diffusion properties, and pervaporation properties were investigated systematically.The hydrophilicity of PEK-C can be effectively endowed by reacting it with concentrated sulfuric acid, and the hydrophilic-hydrophobic balance of the membranes can be realized by controlling the sulfonation degree （SD）, and the membranes maintain well swelling resistance in the acetic acid aqueous. The pervaporation separation index （PSI） of the SPEK-C membranes increased with SD increasing, and it arrived at an optimum when the SD is 0.75. The membranes has good separation performance with a permeation flux of 248 gm^-2h^-1 and separation factor of 103 at 50℃at the feed water content 10wt%.In order to improve the permeation flux of the SPEK-C membranes, PVA and SPEK-C blending membranes were prepared. SEM result shows that the PVA and SPEK-C are compatible, and the membranes are homogeneous. XRD indicates that the intermolecular distance of the polymer chains increases with PVA content increasing. The permeation flux increases and the separation factor decreases with PVA content increasing. The PSI of the membranes increases with increasing PVA content and arrived at a maximum when the PVA content is 40wt%, then decreases with further addition of PVA. The membrane has an encouraging separation performance with a permeation flux of 492 gm^-2h^-1 and separation factor of 59.3 at 50℃at the feed water content 10 wt%.The "trade-off" effect of PVA/SPEK-C blending membranes was solved by filling high hydrophilic silicotungstic acid （STA） into the blending membranes. The pervaporation results show that the permeation flux increased with STA content increasing; however, the separation factor increased with STA content increasing, and arrived at a maximum when the STA content is 12 wt%, then decreased with STA content further increasing. The PSI of the membranes achieved the maximum when the STA content is 12wt%. The membranes show encouraging separation performance with a permeation flux of 597 gm^-2h^-1 and separation factor of 70.3 at 50 C at the feed water content 10wt%.Glutaraldehyde （GA） cross-linked SPEK-C and STA-PVA-SPEK-C homogeneous membranes and composite membranes with a microporous PEK-C substrate were prepared. The PV performance of the homogeneous and composite membranes was investigated. The PV results show that the performance of composite membranes is higher than that of homogeneous membranes under the same operation condition. SEM and PV experiments show that the compatibility between the STA-PVA-SPEK-C/GA layer and the PEK-C substrate and PV performance can be improved by using water and DMSO as a co-solvent for STA-PVA-SPEK-C/GA instead of using DMSO as a solvent only. The permeation flux and separation factor of STA-PVA-SPEK-C-GA/PEK-C composite membranes, using water and DMSO as a co-solvent, could be to 592 gm^-2h^-1 and 91.2 at 50℃at the feed water content 10wt%, respectively.更多还原