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Separation of supercritical fluid mixtures with a membrane process

用膜工艺分离超临界流体混合物

基本信息

批准号：
02453111
负责人：
OHYA Haruhiko
金额：
$ 3.26万
依托单位：
Department of material science and chemical engineering, Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02453111/
关键词：
Membrane Gas separation Supercritical fluid Polyimide Polyamic acid Asymmetric High temperature polyimide polyamic acid

项目摘要

Asymmetric polyamide Kapton^R membrane was made by casting a solution of 18 wt% polyamic acid and 5 wt% phenanthrene in dimethylacetainide at 70ﾟC with a four-minutes evaporation time. Usine this membrane, a separation factor alpha_<ethanol/CO2>, 8.7 was obtained at 373 K and 15 MPa and 6.5 at 423 K and 15 MPa for the experimemt involving the separation of gaseous mixtures Of CO_2 and ethanol with a concentration ratio of 15 : 1. Its value at 373 K is 1.3 times higher than at 423 K, and increases with total pressure, while the separation factor at 423 K remains constant with pressure.The activation energies of permeability were 2.6 kj/mol for ethanol and 7.1 kj/mol for supercritical CO_2・These values are very small compared to those of 48 kj/mol for ethanol and 25 kj/mol for CO_2 with the symmetric polyamide membrane. Supercritical fluid permeation experiment might be the best method to determine the permeation mechanism whether pore flow model or solution-diffusion model, from the measurement of activation energy of permeation.From the data obtained, a calculation was carried out to determine the required membrane area for 90% recovery of ethanol from mixtures with an initial concentration of 1 mol% and a feed rate of 36 mol/h. This area is 0.82 m^2 for separations conducted at 10 MPa and 373 K and 0.28 m^2 at 15 MPa and 373 K. And three quarters of operating energy of pressurization might be saved. Therefore, the process integrated with membrane recovery could save operating energy about 3/4 and the size of the main compressor will be reduced to 1/4 theoretically.

不对称聚酰胺Kapton ® R膜通过在70 ° C下用4分钟蒸发时间浇铸18重量%聚酰胺酸和5重量%菲在二甲基乙酰胺中的溶液来制备。在373 K、15 MPa和423 K、15 MPa条件下，用该膜分离浓度比为15：1的CO_2和乙醇混合气体，其分离因子α_<乙醇/CO_2>分别为8.7和6.5。其值在373 K时比在423 K时高1.3倍，并且随着总压的增加而增加，在423 K时，分离因子随压力的变化保持不变，渗透活化能分别为乙醇2.6 kJ/mol和超临界CO_2 7.1 kJ/mol，与乙醇48 kJ/mol和CO_2 25 kJ/mol相比，这一数值很小2与对称聚酰胺膜。超临界流体渗透实验是确定渗透机理的最佳方法，无论是孔流模型还是溶解-扩散模型，都可以从渗透活化能的测定中确定，并根据所得数据计算出在进料速率为36 mol/h、初始浓度为1 mol%的混合物中乙醇回收率为90%所需的膜面积。对于在10 MPa和373 K下进行的分离，该面积为0.82 m^2;对于在15 MPa和373 K下进行的分离，该面积为0.28 m^2。可节省增压运行能耗的四分之三。因此，与膜回收集成的工艺在理论上可以节省操作能量约3/4，主压缩机的尺寸将减少到1/4。