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Aerogel is the solid material with the lowest thermal conductivity and lowest density known at present. It has an extremely long service life, strong thermal insulation performance, and ultra-high fire resistance. It is known as "the magic material that changes the world". It is also known as "blue smoke" because it is as light as mist and blue in color.

Aerogels have excellent performance, flexible and wide application fields, and are widely used in aerospace, petrochemical, military, construction, transportation, batteries and other fields. Aerogels have large market demand, high cost performance ratio, and can replace large space.

High temperature resistance, high elasticity, strong adsorption and other characteristics

Aerogel is a new type of nano porous solid material. The volume of all pores together accounts for the vast majority of the volume of the entire aerogel, even more than 99%. It has special microstructure characteristics such as high specific surface area, high void ratio, nano pores, low density, etc. It has stable chemical performance, low thermal conductivity, high temperature resistance, high elasticity, strong adsorption, good waterproof effect, wide temperature range and long life.

"Aerogel can be understood as a nano version of porous sponge." Wang Beier, a technical expert in the field of aerogel, said that its pore diameter is between 20 nm and 50 nm. The size of the air molecule is about 70 nm, which is larger than the diameter of the pores of the gel, so the air flow efficiency on the gel is extremely low. In addition, the specific heat capacity of the gel itself is very high, and the heat radiation transfer energy is minimized, so it has good heat insulation performance.

Aerogels can be divided into three categories: inorganic gel, organic gel and organic-inorganic hybrid gel. Among them, inorganic gel are mainly composed of inorganic materials, including simple matter aerogels, oxide aerogels gel and sulfide aerogels gel. Organic aerogels are mainly organic compounds, including phenolic gel, cellulose aerogels, polyimide aerogels, chitosan aerogels, and chitosan cellulose aerogels gel. Organic inorganic hybrid aerogels can use the respective advantages of organic and inorganic materials to realize the special functionalization of aerogels, Huacheng Import and Export Data Observation Report.

In 2021, Science magazine listed aerogel as one of the top ten popular science and technology, and called it "a multi-functional new material that can change the world". Wang Beier said that aerogel is the only one among the top ten new materials selected by Science magazine that has been applied to the actual business scene on a large scale. Huacheng Import and Export Data Observation Report.

The preparation process of gel is mainly divided into two steps, that is, the gel is prepared through the sol gel process, and then the liquid matter in the gel is replaced by the gas by a certain drying method, so as to prepare the aerogel.

According to Huacheng Import and Export Data Observation, manufacturing costs account for about 45% of the cost structure of the aerogel industry. Zheng Song, assistant to the chairman of Suzhou Jinfu Technology Co., Ltd., said that reducing the cost of aerogel is a direction the industry is striving for. At present, one of the main paths is the landing of automated production lines, and cost reduction will open up more application scenarios.

Market pattern of aerogel

With the continuous maturity of aerogel application technology, the continuous promotion of industrialization, and the strong support of superposition policies, the output and demand have been greatly increased in recent years.

In terms of output, the output of China's aerogel materials and aerogel products will be 121000 m3 and 154000 tons respectively in 2021, and the CAGR will be 20.8% and 32.6% respectively in 2016-2021.

In terms of demand, China's demand for aerogel materials and aerogel products will be 119000 m3 and 179000 tons respectively in 2021, and CAGR will be 25.1% and 21.2% respectively in 2016-2021.

In terms of market size, from 2018 to 2021, China's aerogel market size will grow from 925 million yuan to 1.756 billion yuan, with an annual growth rate of more than 20%.

In the future, in the context of energy conservation and emission reduction, with the continuous promotion of gel industrialization, its cost is expected to continue to decline. While the oil and gas field is the cornerstone of demand, construction, transportation and other emerging fields are becoming new drivers of demand growth for gel.

According to the prediction of Aspen Aerogel's 2020 annual report, the domestic demand for aerogel will reach 1 million m in 2025 ³/ In, the corresponding market space was about 15 billion yuan, an increase of more than 7.5 times over 2021; Global demand will reach 1.6 million m ³/ In, the market size reached US $4.6 billion. According to the Aspen forecast data quoted by Aibang Polymer, the market space of aerogel products in the field of electric vehicle thermal insulation will reach 30 billion dollars from 2021 to 2030, and the industry has a large growth space.

Research Status of Aerogel Materials

In 1931, American scholar Kistler successfully prepared SiO2 aerogel materials by using supercritical ethanol fluid drying method and sodium silicate as raw material, while maintaining the gel structure, replacing the ethanol liquid in the network structure with gas. Later, he successively prepared inorganic aerogels such as Al2O3, W2O3, Fe2O3, NiO3, and organic aeronenenebd gels such as cellulose, gelatin, agar. Major countries have paid great attention to the research of aerogel materials, developed a variety of new aerogel materials, and expanded the application range of aerogel.

（1） Major countries have developed a variety of new aerogel materials

The preparation process of aerogel can be divided into two steps: one is to prepare gel through the sol gel process; The other is to use a certain drying method to replace the liquid substances in the gel with gas, so as to prepare the aerogel. The drying process can be divided into supercritical drying, subcritical drying, freeze drying, atmospheric drying and other methods. Among them, the sol gel process is the core process for the preparation of aerogels, which directly determines the various microstructures and properties of aerogels, including hydrolysis and polycondensation.

In recent years, researchers from China, the United States and Europe have developed a variety of new aerogel materials such as bio based aeronenenebb gel, graphene aeronenenebc gel and polymer aeronenenebd gel by improving the preparation process of aerogels. Researchers at the University of Colorado in the United States used the waste from the beer brewing industry as the culture medium, used bacterial cellulose prepared by Acetobacter, and prepared a bacterial cellulose aerogel material through supercritical drying and other methods, which has the characteristics of low thermal conductivity. Researchers from the French National Science Research Center used hydrothermal treatment method different from the traditional preparation process to prepare tannin based carbon aerogels with high specific surface area and specific electric capacity. Researchers from Shandong University have successfully prepared a high-performance amidoxime modified cyclodextrin/graphene aerogel, which shows strong affinity and selectivity for uranium in seawater. It has excellent uranium extraction ability in natural seawater, and 19.7mg/g of uranium can be adsorbed in 21 days. Researchers from Sichuan University, China, used bi-directional oriented carbon aerogels to composite multi walled carbon nanotubes, and developed a new polymer aerogel material that can maintain functionality and hyperelasticity at extreme temperatures. It can play a role in the temperature range of - 196 ℃ to 500 ℃.

（2） Biomass based aerogel material has become a major national research hotspot

Carbon aerogel (CA) is a new type of nano porous carbon material obtained from organic gel as the precursor after pyrolysis in inert gas atmosphere. At the same time, it has the characteristics of high porosity, high specific surface area and low density of aerogel, as well as the characteristics of carbon materials such as heat resistance, acid and alkali resistance and high conductivity. However, due to its complex process, long production cycle, small production scale and expensive raw materials, it is easy to cause environmental pollution, The industrial production and application of carbon aerogel are limited. However, biomass raw materials have a wide range of sources, low cost and rich carbon sources, so it is an economic and sustainable production method to prepare environmentally friendly porous carbon fiber aerogels from biomass raw materials.

Chinese, American and European researchers have carried out research on the preparation and application of biomass based aerogel materials, and achieved a series of research results. Researchers from the French National Science Research Center dissolved the cellulose material in sodium hydroxide solution to prepare a new highly porous pure cellulose aerogel material, whose internal specific surface area is 200-300m2/g and density is only 0.06-0.3g/cm3. Researchers at the University of Colorado in the United States used the waste of the beer brewing industry as the culture medium to prepare bacterial cellulose using Acetobacter, and then prepared bacterial cellulose aerogel materials with low thermal conductivity by supercritical drying and other methods. Researchers from the China Australia Advanced Materials and Manufacturing Research Institute (IAMM) of Jiaxing University in China developed cellulose nanofiber based gel with underwater mechanical tenacity, high elasticity and super hydrophilicity, which can be used for water in oil lotion separation and solar steam power generation. It solved the problem of poor water resistance and low underwater mechanical tenacity of cellulose aerogel, and broke the barrier of its application.

（3） 3D printing aerogel materials have made many technical advances

Due to the limited mechanical properties of traditional aerogels, it is difficult to form the required complex shape structure through post processing. Therefore, 3D printing technology for customized preparation of complex shape structure materials is expected to become an advanced manufacturing technology that breaks through the bottleneck of application of aerogel materials. In 2015, researchers at the University of California in the United States prepared graphene aerogels through 3D printing technology for the first time. Since then, 3D printing aerogels have gradually become a research hotspot. At present, there are three main printing methods in the preparation of 3D printing aerogel materials: extrusion, cold field assisted on-demand drop (DOD) and UV curing. According to the main composition of 3D printing aerogels, they can be divided into 3D printing carbon aerogels, 3D printing inorganic aerogels and 3D printing organic aerogels. The researchers of Akron University in the United States first used the stereo light curing molding (SLA) technology to make small bricks similar to Lego bricks, and then used the fused deposition manufacturing (FDM) process to make the forming mold. After injecting aerogel into the mold and bricks, after demoulding, curing and other post-processing, the modular production of aerogel bricks was realized. Researchers in the Swiss Federal Laboratory of Materials Science and Technology directly use the slurry of silica aerogel powder to directly write and print micro silica aerogel objects. This object has high specific surface area and ultra-low thermal conductivity, which can be used as thermal insulator and micro air pump and can degrade volatile organic compounds.

The development of aerogel has entered the "fast lane"

According to Huacheng Import and Export Data Observation, the development of aerogel has been continuously supported by national policies. In 2014 and 2015, the National Development and Reform Commission listed aerogels in the National Key Energy Saving and Low Carbon Technology Promotion Catalog for two consecutive years, and began to preliminarily promote and apply aerogels; In June 2018, aerogel was listed in the emerging industry of building materials; In September of the same year, the first national standard for aerogels, Nanoporous Aerogel gel Composite Thermal Insulation Products, was released; In 2020, the Technical Standard for Aerogel Thermal Insulation Coating System will be launched; In 2021, the Opinions of the CPC Central Committee and the State Council on Completely, Accurately and Comprehensively Implementing the New Development Concept and Doing a Good Job in Carbon Peak and Carbon Neutralization was put forward to promote the research, development and application of new materials such as aerogels.

With the continuous maturity of aerogel application technology, aerogel has entered the "fast lane" of development. However, Li Weike said that at present, there are still some problems in the research of aerogels. For example, the thermal conductivity of aerogels increases rapidly at high temperatures, and their adhesion to fiber and other reinforced matrix materials is poor; Many organic solvents will be used in the production process, which is easy to cause environmental pollution; It is difficult to recycle aerogel, which is not conducive to sustainable development.

In addition, the production cost of aerogel is high, and the product price is expensive. The 2022 Aerogel Industry Research Report points out that the production cost of aerogel is mainly concentrated in the raw material silicon source, equipment depreciation and energy consumption. Effective cost reduction depends not only on breakthroughs in preparation technology, but also on large-scale industrialization of low-cost raw materials.

Aerogel is a rare material that can simultaneously meet the needs of fire prevention, waterproof, heat insulation, sound insulation and other needs. Li Weike said that the development and application of gel are still in the process of continuous exploration, and the future research direction will mainly focus on the development of cellulose aerogels, graphene aerogels, perovskite structure aerogels, non-metallic elemental aerogels gel and other new aerogels.

The development and application of aerogel materials are still in the process of continuous exploration. Although research progress has been made in some fields, problems such as insufficient resource utilization, high manufacturing costs, and defects in technology and process still need to be solved. Major countries will also develop fierce competition in this field. China's research level in the field of aerogel materials is in the forefront of the world. We should continue to carry out research on the preparation and large-scale production process of aerogel materials, expand the application field of aerogel materials, and maintain a leading position in this field. Huacheng Import and Export Data Observation Report.