Activated alumina as a catalyst and carrier for chemical reactions
Activated alumina has a large specific surface area, a variety of pore structures and pore size distributions, and rich surface properties. Therefore, it has a wide range of uses in adsorbents, catalysts and catalyst carriers. Alumina for adsorbent and catalyst carrier is a fine chemical and also a special chemical. Different uses have different requirements for physical structure, which is the reason for its strong specificity and many varieties and grades. According to statistics, the amount of alumina used as catalysts and carriers is more than the total amount of catalysts using molecular sieve, silica gel, activated carbon, diatomaceous earth and silica alumina gel. This shows the pivotal position of alumina in catalysts and carriers. Among them, η-Al2O3 and γ-Al2O3 are the most important catalysts and supports. They are both spinel structures containing defects. The difference between the two is: the tetrahedral crystal structure is different (γ>η), and the hexagonal layer stack The row regularity is different (γ>η) and the Al—O bond distance is different (η>γ, the difference is 0.05～0.1nm).
Carbon molecular sieves is a new type of non-polar adsorbent
The ability of molecular sieve to separate air depends on the diffusion speed of various gases in the air in the pores of Carbon Molecular Sieves, or the adsorption force, or both. Carbon Molecular Sieves PSA air separation nitrogen production is based on this performance. Carbon Molecular Sieves are used to produce nitrogen. The N2 concentration and gas production volume can be adjusted according to the user's needs. When the gas production time and operating pressure are determined, the gas production volume will be lowered, and the N2 concentration will increase, otherwise, the N2 concentration will decrease. Users can adjust according to actual needs.
Influence of molecular sieve in PSA nitrogen generator
Carbon molecular sieve PSA nitrogen generator production relies on van der Waals force to separate oxygen and nitrogen. Therefore, the larger the specific surface area of the molecular sieve, the more uniform the pore size distribution, and the greater the number of micropores or submicropores, the greater the adsorption capacity; , If the pore size can be as small as possible, the van der Waals force field overlaps, and it has a better separation effect on low-concentration substances. Carbon molecular sieve is a non-quantitative compound, and its important properties are based on its microporous structure. Its ability to separate air depends on the different diffusion speeds of various gases in the air in the pores of the carbon molecular sieve, or different adsorption forces, or both effects work at the same time. Under equilibrium conditions, the adsorption capacity of carbon molecular sieve for oxygen and nitrogen is quite close, but the diffusion rate of oxygen molecules through the narrow gaps of the carbon molecular sieve microporous system is much faster than that of nitrogen molecules. Carbon molecular sieve air separation nitrogen production is based on this Performance, before the time to reach equilibrium conditions, the nitrogen is separated from the air through the PSA process.
What is carbon molecular sieve？
Carbon molecular sieve is a new type of adsorbent developed in the 1970s. It is a kind of excellent non-polar carbon-based cellulose material. Carbon Molecular Sieves (CMS) is used for separation and enrichment of air. Nitrogen adopts a normal temperature and low pressure nitrogen production process, which has the advantages of less investment cost, faster nitrogen production speed, and lower nitrogen cost than the traditional cryogenic high pressure nitrogen production process. Therefore, it is currently the preferred pressure swing adsorption (PSA) nitrogen-rich adsorbent for air separation in the engineering industry. This nitrogen is used in the chemical industry, oil and gas industry, electronics industry, food industry, coal industry, pharmaceutical industry, cable industry, and metal It is widely used in heat treatment, transportation and storage. R & D background In the 1950s, with the tide of the industrial revolution, the application of carbon materials became more and more extensive. Among them, the application field of activated carbon was PSA carbon molecular sieve for nitrogen production. The expansion is the fastest, from the initial filtration of impurities to the separation of different components. At the same time, with the advancement of technology, mankind's ability to process materials has become stronger and stronger. In this case, carbon molecular sieves have emerged. Main components of carbon molecular sieve The main component of carbon molecular sieve is elemental carbon, and the appearance is a black columnar solid. Because it contains a large number of 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 in the air. The pressure swing adsorption device (PSA) is used in industry to produce nitrogen. Carbon molecular sieve has large nitrogen production capacity, high nitrogen recovery rate and long service life. It is suitable for various types of PSA nitrogen generators and is the first choice for PSA nitrogen generators. Carbon molecular sieve air separation nitrogen production has been widely used in petrochemical, metal heat treatment, electronics manufacturing, food preservation and other industries. working principle Carbon molecular sieve uses the characteristics of sieving to achieve the purpose of separating oxygen and nitrogen. When the molecular sieve adsorbs impurity gas, the macropores and mesopores only play the role of channels, transporting the adsorbed molecules to the micropores and submicropores, and the micropores and submicropores are the real adsorption volume. As shown in the previous figure, the carbon molecular sieve contains a large number of micropores. These micropores allow molecules with a small dynamic size to rapidly diffuse into the pores while restricting the entry of large-diameter molecules. Due to the difference in the relative diffusion rate of gas molecules of different sizes, the components of the gas mixture can be effectively separated. Therefore, when manufacturing carbon molecular sieves, according to the size of the molecules, the distribution of micropores inside the carbon molecular sieve should be 0.28 to 0.38 nm. Within the size range of the micropores, oxygen can quickly diffuse into the pores through the pores of the micropores, but it is difficult for nitrogen to pass through the pores of the micropores, thereby achieving oxygen and nitrogen separation. The pore size of the carbon molecular sieve is the basis for the separation of oxygen and nitrogen. If the pore size is too large, oxygen and nitrogen molecular sieves can easily enter the pores and cannot separate; and if the pore size is too small, neither oxygen nor nitrogen can enter. In the micropores, there is no separation effect.
The difference between 3a, 4a, 5a molecular sieves
The difference between 3a, 4a, and 5a molecular sieves is mainly due to the different uses, such as the difference in bulk density and compressive strength. Many people who do not understand will think that the difference between these different molecular sieves is in diameter. In fact, this is wrong. Let’s compare the differences and similarities of these three molecular sieves. 3A molecular sieve The bulk density is 680Kg/m³, and the compressive strength (N)≧80/P. Mainly used in the drying of petroleum cracking gas, olefin, gas training field, oil field equipment, and industrial dryer for chemical industry, medicine, hollow spirit, etc. 4A molecular sieve The bulk density is 680Kg/m³, and the compressive strength (N)≧80/P. Mainly used for the drying of natural gas and various chemical gases and liquids, refrigerants, medicines, electronic materials, and abnormal substances. 5A molecular sieve , The bulk density is 680Kg/m³, the compressive strength (N)≧80/P. Mainly used for natural gas drying, desulfurization, carbon dioxide removal, nitrogen and hydrogen separation, production of oxygen, nitrogen and hydrogen, petroleum dewaxing, etc. Molecular sieve has 3A/4A/5A/10X/13X and other models, each model has diameters of 0.4-0.8mm, 1-2mm, 1.6-2.5mm, 2-4mm, 3-5mm and 4-6mm. Molecular sieve.
Carbon molecular sieve adsorption and desorption process
The main component of Carbon molecular sieve is elemental carbon, and the appearance is a dark gray cylindrical solid. Because it contains many microporous plates with a diameter of 4 angstroms, the microporous plates have a strong instant appeal to oxygen molecules, and can be used to extract CO2 and N2 in the air. Pressure swing adsorption machinery and equipment ( PSA) Make N2. Carbon molecular sieve has a large nitrogen production capacity, a high N2 utilization rate, and a long service life. It can be used with various specifications and models of pressure swing adsorption nitrogen generators. It is a product of pressure swing adsorption nitrogen generators. Carbon molecular sieve air separation nitrogen production has been widely used in petrochemical equipment, machinery and equipment, metal surface solution, electronic component production and processing, vegetable preservation and other industries. Basic concept of production process Carbon molecular sieve absorption and treatment of organic waste gas is the application of Carbon molecular sieve microplates to digest and analyze the characteristics of chemical compounds, and absorb the organic solvents in the lower concentration of analytical chemical industrial waste gas into Carbon molecular sieve. After purification, the gas after suction and cleaning up to the standard is emptied immediately. The essence is a physical absorption and purification process. The organic solvents are not disposed of. Absorption is the use of the remodeling machinery and equipment produced by our company to melt the organic waste gas caused by the air heating of the organic solvent absorbed in the Carbon molecular sieve to ensure the melting point of the solvent, so that the organic solvent is absorbed from the Carbon molecular sieve And introduce the purified industrial waste gas with a higher concentration value into the catalytic combustion device equipment. The oxidation-reduction reaction of organic waste gas with a higher concentration value in the remodeling machinery and equipment reflects the conversion into harmless water and carbon dioxide into the gas. Absorption can be carried out in addition, using multiple Carbon molecular sieve adsorption beds for adsorption treatment, in addition to one bed for adsorption development prospects, suitable for continuous production and processing sites. Advantages of production process 1. High professional ability to absorb organic molecules in industrial waste gas; 2. High temperature resistant and not easy to corrode; 3. Molecular sieves can be continuously reshaped. The catalytic reaction speed is used to reshape the machinery and equipment to reshape it on time, and the concentrated gas produced in the manufacturing process enters the remolding machinery and equipment and is compounded, resulting in harmless gas sewage treatment and difficult to correct Geographical environment causes secondary pollution; 4. It saves operating costs and does not need to be disassembled on time like activated carbon.
