Introduction to carbon molecular sieve.
Carbon molecular sieve is a new adsorbent developed in 1970s. It is a good non-polar carbon material. Carbon molecular sieves (CMS) for nitrogen production are used to separate air and enrich nitrogen. Adopt low pressure nitrogen technology at room temperature. Compared with the traditional low temperature and high compression nitrogen process, it has the advantages of low investment cost, fast nitrogen production speed and low cost of nitrogen production. Therefore, it is a recommended PSA nitrogen-rich adsorbent in engineering field. This nitrogen is widely used in chemical industry, oil and gas industry, electronics industry, food industry, coal industry, pharmaceutical industry, cable industry, metal heat treatment, transportation and storage.
In the 1950s, with the wave of the industrial revolution, the application of carbon materials is more and more extensive, and the application of activated carbon is used in PSA carbon molecular sieve for nitrogen production
From the initial filtration of impurities to the separation of different components, the expansion rate is fast. At the same time, with the progress of technology, the ability of human beings to process materials has become stronger and stronger. In this case, carbon molecular sieve emerged.
The main component of carbon molecular sieve is simple carbon, and its appearance is black columnar solid. Since there are many micropores with a diameter of 4 angstroms, the micropores have a strong instantaneous affinity for oxygen molecules and can be used to separate oxygen and nitrogen from air. In industry, pressure swing adsorption (PSA) is used to produce nitrogen. Carbon molecular sieve has high nitrogen production capacity, high nitrogen recovery rate and long service life. Suitable for various types of PSA nitrogen machine, PSA nitrogen machine is the recommended product.
Carbon molecular sieve air separation of nitrogen has been widely used in petrochemical, metal heat treatment, electronic manufacturing, food preservation and other industries.
Carbon molecular sieve is a sieve that uses sieving characteristics to separate oxygen and nitrogen. When molecular sieve adsorbs impurities, macropores and mesopores are only used as channels to transport adsorbed molecules to micropores and submicrons, and micropores and submicrons are adsorption volumes. As shown above, carbon molecular sieves contain a large number of micropores, which allows molecules with smaller kinetic sizes to rapidly diffuse into the pores, while also limiting the entry of larger diameter molecules. Because the relative diffusion rate of gas molecules of different sizes is different, the components of gas mixtures can be separated effectively. Therefore, in the manufacture of carbon molecular sieve, according to the molecular size, the distribution of micropores in carbon molecular sieve should be 0.28~0.38 nm. Within the size range of the micropore, oxygen can rapidly diffuse into the micropore, while nitrogen is difficult to pass through the micropore, thus achieving oxygen and nitrogen separation. The pore size of micropores is the basis of carbon molecular sieve separation of oxygen and nitrogen. If the pore size is too large, oxygen, nitrogen molecular sieve easy to enter the micropore, can not play a role in separation; If the pore size is too small, neither oxygen nor nitrogen can enter the micropore and be separated.
Due to the limitation of conditions, the pore size of domestic molecular sieve has not been well controlled. The micropore size of carbon molecular sieve on the market is 0.3~1nm, and only the rock molecular sieve reaches 0.28~0.36nm. Carbon molecular sieve raw materials are coconut shell, coal, resin, etc. The first step is processing, followed by crushing, and then mixing with the substrate. The base material is mainly used to increase strength and prevent crushing; The second step is to activate pore formation. The activator was introduced at 600~1000℃. Common activators are water vapor, carbon dioxide, oxygen and their mixtures. They react thermochemically with active amorphous carbon atoms, increasing the specific surface area and gradually forming holes. The activation time of pore formation was 10-60 minutes. The third step is to adjust the pore structure. The vapor of benzene and other chemical substances is deposited on the micropore wall of carbon molecular sieve to adjust the pore size to meet the requirements.