First, about high performance membrane materials

High performance membrane material is the core of the new type of efficient separation technology, has the characteristics such as energy saving and environmental friendly, is to address the issue of water resources, energy, environmental and industrial technologies to upgrade traditional strategic new materials, has become a supporting environment pollution control, energy conservation and emissions reduction, the people's livelihood security areas such as one of the key common technology, It plays an important role in promoting the development of Chinese national economy, national technical progress and enhancing international competitiveness.
High performance membrane materials have the characteristics of high separation performance, high stability, low cost and long life. According to the different application objects of membrane materials, it can be divided into water treatment membrane, special separation membrane, gas separation membrane, biomedical membrane, battery membrane and so on. Among them, water treatment membrane can be divided into microfiltration membrane, ultrafiltration membrane, nanofiltration membrane, reverse osmosis membrane, etc. Special separation membrane can be divided into ceramic film, ion exchange film, pervaporation film, etc. Gas separation film can be divided into gas-gas separation film, gas-solid separation film, volatile organic compounds recovery film.
The industrial chain of high-performance membrane materials includes membrane raw materials, membrane components, membrane components, membrane separation devices and industrial application systems, etc. It belongs to the cross fields of materials, chemical industry, energy, biology, environment and so on. Its research and development level plays a vital role in the development of process industry, environmental protection and other industries.

Ii. Current situation and trend of world development

High performance membrane materials have been highly valued by governments of various countries, and the membrane material industry has an annual growth rate of about 15%. Among them, the water treatment membrane material has realized industrialization and large-scale application, entered a relatively mature period, occupy the majority of the market share, the market growth rate has slowed down; Special separation membrane materials are in the stage of rapid industrial development, membrane varieties and application scale continue to increase, sales into a period of rapid growth; At present, gas separation membrane materials have been initially industrialized. With the improvement of environmental protection requirements, gas-solid separation membrane, volatile organic compounds recovery membrane and other rapid development, broad prospects.

01 Gas separation membrane material

In terms of gas separation membrane materials, carbon dioxide separation membrane, hydrogen separation membrane, organic steam recovery membrane, gas-solid separation membrane, etc., have realized industrial production, and have been applied in natural gas purification, hydrogen recovery, organic steam recovery, gas dust removal and other fields. However, high temperature mixed conductor oxygen permeable film for pure oxygen separation, fixed carrier film for carbon dioxide separation, palladium film and alloy film for high temperature hydrogen separation and purification are still in the early stage of industrialization. The development trend is mainly focused on reducing the cost of membrane materials, improving the selectivity, permeability and operation stability of membrane materials, and the study of gas separation membrane containing fluorine.
Internationally, membrane material research and development and industrial scale production institutions, mainly concentrated in the United States, Japan and Europe and other developed countries and regions. Main research and development institutions include: French National Institutes of Sciences, National University of Singapore, University of Leuven, Russian Research Institute, US Department of Energy, University of Tuen Mun, etc. The main production enterprises include Toray, Nitto Denko, Kubota, GE, DOW, NGK, GFT, Air Products, UOP, Ube, Pall and other companies.

02 Special separation membrane material

In terms of special separation membrane materials, ceramic ultrafiltration membrane has been industrialized production, and has been widely used in the field of process industry, ceramic nanofiltration membrane has been put on the market; The development trend mainly focuses on the research and development of ceramic membrane with high loading density, the low temperature preparation technology of ceramic ultrafiltration membrane, the improvement of the separation performance and operation stability of ceramic nanofiltration membrane, and the development of high-performance ceramic membrane materials for membrane distillation, membrane desulfurization and industrial wastewater treatment and other application processes.
Pervaporation membrane material has been widely used in alcohol-water separation, and has been gradually applied to the separation of organic matter. The development trend mainly focuses on improving the stability and acid resistance of pervaporation film materials. At present, ceramic membrane crystallization and membrane distillation technology has been developed in Italy. The United States is focusing on promoting the application of ceramic membranes in the oil and gas industry.

03 Water treatment film material

In terms of water treatment membrane materials, reverse osmosis membrane materials used in the desalination process have formed high pressure, medium pressure and low pressure series products and dominate the market; The development trend mainly focuses on the performance improvement of polyamide reverse osmosis membrane materials, the development of new membrane materials and membrane processes, the development of large membrane elements, and the further improvement of membrane operation stability, increasing desalting rate and water production, reducing operation energy consumption and production costs, etc.
Membrane materials used for water purification, ultrafine membrane materials have been widely used in drinking water, seawater desalination and water reuse pretreatment, sewage treatment and other large-scale water treatment projects and tend to mature, nanofiltration membrane materials have been large-scale production, engineering applications in the field of tap water deep purification; The development trend is mainly focused on improving permeability flux, pollution resistance and oxidation resistance, reducing membrane manufacturing cost and so on.
Membrane bioreactors for wastewater treatment have been put into practice, and the market share of membrane components for lined enhanced membrane bioreactors has been rapidly developed. The development trend is mainly focused on improving the pollution resistance and mechanical properties of membrane materials, as well as improving the water quality and so on.
In the research and development of water treatment membrane materials, reverse osmosis membrane has made great progress. By using the 3D printing technology based on reactive monomer electrospray instead of the traditional interfacial polymerization technology, American scientists successfully realized the nano-level fine control of the film thickness and surface roughness of polyamide reverse osmosis membrane materials. Compared with commercial reverse osmosis membrane products, it has higher NaCl rejection rate and pure water penetration rate, and its comprehensive performance is significantly improved (Science,2018).
Dow has developed high-performance polyamide reverse osmosis membranes with high throughput, low energy consumption and moderate desalting by using the complexing agent and acyl halide functional group to control the interfacial polymerization process before the interfacial polymerization.

Third, our country development present situation and level

In recent years, China has made great progress in the direction of water treatment membrane materials, special separation membrane materials and gas separation membrane materials, the performance of water treatment membrane materials has been improved significantly, and narrowed the gap with the international advanced level, special separation membrane materials and gas separation membrane materials have reached the international advanced level. Domestic membrane production capacity has been rapidly expanded, and has been widely used in wastewater treatment, food, medicine, chemical industry and other fields, the industry's scientific and technological innovation ability and industry market competitiveness has been significantly improved, by 2019 statistics, membrane industry scale has been nearly 200 billion yuan.

01 Gas separation membrane material

In terms of gas separation membrane materials, high performance metal membrane materials for gas-solid separation have been industrialized and applied to the production process of nuclear fuel, polysilicon and non-ferrous metallurgy in China. At present, they are developing towards higher precision and multi-function. Their technical achievements have won the second prize of the National Technological Invention Award in 2017. Developed new polytetrafluoroethylene membrane material and built a large-scale production line; Membrane materials have been successfully used in the purification of boiler exhaust gas, waste incineration flue gas treatment, dye product recovery and other fields.
In the respect of membrane materials for organic solvent recovery, our country has developed new polyoctyl methylsiloxane membrane materials, developed high performance volatile organic compounds recovery membranes, improved the swelling resistance and selectivity of composite membranes, realized the low cost, low energy consumption of light hydrocarbons recovery industrial applications; The organic and inorganic composite volatile organic compounds recovery membrane has been developed, and the world's largest organic gas separation membrane production base has been built, which has been widely used in volatile organic compounds recovery in petroleum, chemical, pharmaceutical and other industries.

02 Special separation membrane material

In the aspect of special separation membrane materials, China's ceramic membrane materials have made important progress in the small pore size membrane materials, water-oriented treatment and solvent separation. A series of ceramic nanofiltration membrane products, such as TiO, ZrO, TiO/ZrO and RGO, have been developed by using improved sol-gel technology. By using AlO membrane as the core material of vacuum membrane distillation technology, efficient desalting process is successfully realized. The annual capacity of TiO/AlO/ZrO ceramic membrane has exceeded 100,000 square meters, which has been successfully applied to the lithium extraction process in salt lake, and the company has been listed on the GEM.
China's flat ceramic membrane has also been industrialized, and successfully applied in Sinopec oil and gas field produced water advanced treatment demonstration project (treatment scale 1440m/d), and China National Coal Group coal methanol chemical wastewater treatment demonstration project (treatment scale 9000m/d).
To meet the needs of organic solvent dehydration, Jiangsu Jiutian Company has developed hollow fiber molecular sieve membranes with high throughput and high loading density, and developed a series of new solvent dehydration processes, which are applied to more than 10 kinds of solvent dehydration with low energy consumption. Its molecular sieve membrane annual capacity of more than 20,000 square meters.
In terms of ion exchange membrane materials, Shanghai Jiao Tong University and Shandong Dongyue Group cooperated to achieve the successful production of the third generation of chlor-alkali ion membrane DF2807, and the product performance reached the international advanced level. Shandong Tianwei Film Company diffusion dialysis film annual capacity of 300,000 square meters; The University of Science and Technology of China (USTC) team has developed a green and scalable homogeneous ion-exchange membrane preparation route by selecting polymers with specific structures and replacing chloromethylation of methyl chloride with bromination process. The ion exchange membrane with low cost and stable performance made by this technology has been industrialized.

03 Water treatment film material

In terms of water treatment membrane materials, the development and application of reverse osmosis membrane materials, water treatment membrane materials and water purification membrane materials have been developed rapidly. Guiyang Times Wharton COMPANY's ANNUAL capacity of reverse osmosis membrane has exceeded 17 million square meters, Jin film TECHNOLOGY company's annual capacity of polyvinylidene fluoride hollow fiber membrane has also exceeded 4 million square meters, Bishuiyuan company has built hundreds of square meters of nanOFILtration membrane production line.
With the rapid development of industrial scale, breakthroughs have also been made in basic research: By introducing potassium ions with minimum hydration diameter between graphene layers, effective interception of all ions in salt solution and rapid transmission of water molecules can be achieved at the same time, which is expected to be used in seawater desalination (Nature,2017). By adding polyvinyl alcohol to the aqueous phase to improve the diffusion coefficient difference between the active agent and the inhibitor, the Turing structure was formed, and the water flux and selectivity of the polyamide reverse osmosis membrane were greatly improved (Science,2018). Guiyang Times Wharton Co., LTD developed a new polyamide reverse osmosis membrane product with complete and defected membrane layer and loose membrane pore structure by adding modified graphene oxide in the reaction phase and ethanol in the aqueous phase. It has the characteristics of high desalination rate and high flux.
In general, the R&D and production institutions with strong scientific research strength or industrial scale include: The Chinese Academy of Sciences, tsinghua university, zhejiang university, nanjing university of technology, China university of science and technology, tianjin university, northwest nonferrous metal research institute and other institutes of colleges and universities, as well as the water source, guiyang era Walton, hainan lisheng, hangzhou water treatment center, membrane science and technology, tianjin, Beijing, ningbo qinyuan d, nanjing, jiangsu long we, shandong days nine companies such as thought, jiangsu nine days. There are more than 10 listed companies focusing on the production and application of membrane materials, but overall the scale of enterprises is relatively small, and the innovation ability needs to be further strengthened.

Fourth, further development countermeasures and suggestions

Although high performance membrane materials have made great progress in China, there are still some difficulties and challenges.

First, the original innovation capacity still needs to be strengthened. The separation mechanism and preparation technology of membrane materials have not formed a substantial breakthrough, the basic structure design ability of membrane materials is weak, and the performance and specifications of membrane materials need to be further improved and expanded. Domestic film product tracking imitation more, less original products. Although there are domestic membrane materials in some application fields, there is still a gap between the product performance and foreign products, and the membrane product specifications are not complete, resulting in the actual application of Chinese membrane products is not strong competition.

Second, the achievement conversion rate still needs to be improved. Many original membrane materials stay in the laboratory research stage, the subsequent results of the transformation of the lack of the corresponding platform, funds and manpower support, transformation speed is slow, difficult to achieve application. At the same time, the production of high-performance membrane materials is closely related to the production of raw materials, molding processing, automation control and so on. It belongs to the interdisciplinary field. At present, no effective multi-disciplinary linkage mechanism has been formed to achieve the rapid development of high-performance membrane materials.

Third, it is not enough in large projects or high-end fields. At present, in the high-end application field and large chemical industry process, such as large seawater desalination and large water treatment project, the membrane products used are mostly monopolized by foreign products, and domestic membrane material market share is less than 10%. Although some domestic membrane products have achieved certain market competitiveness, the application system based on "domestic membrane component-membrane equipment-membrane engineering" still needs to be further developed.

In order to further promote the development of high-performance membrane materials technology and industry, it is suggested that:

First, strengthen original basic research. We will focus on the research of homogeneous pore and limited domain plasma transfer membranes, and develop subversive membrane materials such as two-dimensional membrane materials. The molecular design, surface property tuning and pore microstructure control methods for application process membrane materials were constructed. The study of membrane surface, domain limiting effect and material transfer behavior in nanomicro channels during the separation process has made a breakthrough in the basic theory of membrane materials.

2. Develop high-performance membrane material products. In response to major national needs, High performance and low cost water treatment membrane (such as mixed matrix membrane, organic - Inorganic composite membrane materials, reverse osmosis membrane, nanofiltration membrane organic pollution resistance, etc.), special separation membrane with high loading density, low cost, acid type hollow fiber ceramic membrane molecular sieve membrane, advanced ion exchange membrane, etc.) and gas separation membrane (new high recovery of membrane separation membrane, volatile organic compounds, carbon dioxide separation membrane, etc.) and so on large-scale preparation of key technologies, Develop high performance membrane material products for major engineering or high-end applications.

Third, strengthen the application demonstration of domestic membrane materials. Carry out research on membrane integrated application technology, explore the application of domestic membrane technology in coal chemical industry, petrochemical industry, bioenergy and other fields, actively promote the application of membrane technology in the separation of bulk chemicals, especially in the production of electronic solvents and chemicals, and carry out integrated application demonstration; Strengthening the application of high performance membrane materials, promoting it to play important roles in the fields of comprehensive environmental governance of water resources, energy structure adjustment and clean utilization, transformation and upgrading of traditional industries, social development and circular economy, etc.

(Source: Chemical Think Tank)