Olefin/alkane separation membrane and preparation method thereof

Abstract

The invention provides an olefin / alkane separation membrane and a preparation method thereof. The olefin / alkane separation membrane comprises a supporting membrane layer and a separation membrane layer which are sequentially stacked, wherein the separation membrane layer is composed of a polyether-polyamide block copolymer and ionic liquid with a transition metal ion complex as a cation. Accordingto the invention, the synergistic effect of the polyether-polyamide block copolymer and the components in the ionic liquid taking the transition metal ion complex as the cation is utilized; the permeability coefficient of the olefin / alkane separation membrane can be increased to 33*10<-10> / cm<3>(STP).cm / (cm<2>.S.cmHg) or above, the separation coefficient of olefin can reach 7 or above, the service life of the membrane can reach 30 days or above under the condition that moisture wetting is not needed, and the olefin / alkane separation membrane is suitable for further application and popularization.

Description

technical field [0001] The invention relates to the field of composite materials, in particular to an olefin / alkane separation membrane and a preparation method thereof. Background technique [0002] The separation of alkenes / alkanes has always occupied a very important position in the chemical industry. Since alkenes and alkanes have similar physical properties, such as similar boiling points and vapor pressures, traditional chemical processes such as liquefaction and distillation are used to separate Alkenes and alkanes usually require lengthy unit operations and high energy consumption, therefore, the separation of alkenes and alkanes using traditional chemical processes is expensive. According to statistics, 50-75% of the production cost of olefins comes from its separation process. Under the background of high cost and complex process of energy-intensive separation processes such as conventional cryogenic distillation, exploring efficient and energy-saving olefin / alkane...

AI Technical Summary

Problems solved by technology

[0004] At present, the facilitated transfer separation membranes based on the π complexation effect obtained in the prior art are mainly divided into supported liquid membranes, polymer electrolyte membranes and ion exchange membranes according to their structures. The supported liquid membranes belong to the category of liquid membranes and have high selectivity, The mass transfer rate is high, but the liquid membrane itself has poor stability and short life. So far, there is no example of industrial application. The polymer electrolyte membrane and ion exchange membrane with fixed carrier can overcome the problems such as the loss of membrane liquid caused by the structure of the liquid membrane itself, but These two kinds of membranes not only require the amount of carrier during the preparation of the membrane, but also the active olefin carrier is easily poisoned during use.

For example, CN101693167A discloses a composite membrane loaded with transition metals, including a support layer and a separation layer. The support layer is a porous or microporous membrane. Infiltrating transition metal soluble salts to obtain transition metal infiltrating layers, the separation coefficient of the obtained composite membrane for olefins can reach 100; CN107835797A discloses a method for preparing silver polymers, by fluorinating the side chains containing sulfonic acid groups The polymer is contacted with a strong acid such as nitric acid and a silver salt with pKa<1, so that silver ions are attached to the surface of the polymer. When the polymer containing silver ions obtained is used for the separation of alkanes and olefins, the selectivity to olefins can also reach above. However, when the separation membrane material obtained in the above-mentioned prior art is used for alkane / olefin separation, the performance of the carrier transition metal ion in the membrane material is unstable, resulting in that the selectivity of the membrane material to alkene is reduced as the service time increases. And the permeability to gas drops significantly. In addition, the ion exchange membrane also needs to maintain the wettability of the membrane surface by sweeping the inert gas containing water vapor on the membrane surface or side. The above problems are in other similar prior art, such as The membrane materials disclosed in CN106336519A, CN107614465A and CN107683273A also obviously exist, and then the separation membrane obtained in the above prior art cannot be applied to the requirements of separation membrane life, separation efficiency and separation selectivity in the modern industrialized olefin production process

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