Production and application of carbon molecular sieves

Carbon Molecular Sieve (CMS) is a molecular sieve made of carbon-based materials with a unique microporous structure that can effectively screen gas molecules. Its preparation technology and application fields involve complex processes and scientific principles, and are widely used in gas separation, adsorption and storage.

 

Litong Machinery is a molecular sieve made of carbon-based materials with a unique microporous structure that can effectively screen gas molecules. Its preparation technology and application fields involve complex processes and scientific principles, and are widely used in gas separation, adsorption and storage.

1. Preparation method of carbon molecular sieve The preparation of carbon molecular sieve mainly depends on steps such as carbonization, activation and pore size regulation.

The process is roughly as follows:  

The raw materials of carbon molecular sieve are mainly organic polymer materials, such as phenolic resin, polyacrylonitrile (PAN), wood, etc. These materials have rich carbon content and good processability, and are suitable for carbonization into carbon materials through heat treatment processes.  

Carbonization process Carbonization is a key step in the preparation of carbon molecular sieves. The precursor is usually heated to 800-1000°C in an inert atmosphere (such as nitrogen or argon) to cause a pyrolysis reaction. This process removes volatiles (such as water, hydrogen, oxygen, etc.) in the material, leaving a carbon skeleton in the end. Temperature control during carbonization is crucial, as it determines the pore structure of the final material.  

Activation treatment In order to further control the pore size and improve the adsorption performance, carbon molecular sieves usually need to be activated. Common activation methods include physical activation and chemical activation:  

Physical activation: The carbonized material is treated with gases such as water vapor or carbon dioxide at high temperature to further etch the carbon surface and generate more micropores and mesopores.  

Chemical activation:

Activation is performed using chemical reagents such as zinc chloride, phosphoric acid or potassium hydroxide. This method has a high activation efficiency, but a subsequent washing step is required to remove residual chemical reagents.  

Regulating pore size The core feature of carbon molecular sieves is that their pore size is usually between 0.3-0.8 nanometers, which can separate small molecule gases. The size of these pores can be precisely adjusted by controlling the activation conditions, such as activation temperature, time, gas flow rate, etc.  

Post-processing steps After activation, carbon molecular sieves usually need to be post-processed, such as drying, mechanical processing, etc., to obtain the desired physical shape and mechanical properties. The final product can be granular, columnar or blocky, customized according to the needs of different application fields.

2. Application of carbon molecular sieves Carbon molecular sieves have good gas selectivity, chemical corrosion resistance and high mechanical strength, so they are widely used in gas separation, gas adsorption and storage.  

Nitrogen preparation Carbon molecular sieves are widely used in the field of nitrogen preparation, especially in separating nitrogen from the air through **Pressure Swing Adsorption (PSA)** technology. Carbon molecular sieves have strong oxygen adsorption capacity, but almost no nitrogen adsorption, so oxygen can be separated from the air through PSA technology at room temperature and pressure, thereby obtaining nitrogen with a purity of up to 99.99%. This technology is widely used in food packaging, metallurgical industry, electronics industry and other occasions that require high-purity nitrogen.  

Hydrogen purification In the chemical and energy fields, carbon molecular sieves are often used for hydrogen purification. Through the pressure swing adsorption process, carbon molecular sieves can separate impurities such as nitrogen, oxygen, carbon dioxide and methane from gas mixtures, thereby improving the purity of hydrogen. This technology is widely used in fields that require high-purity hydrogen, such as hydrogen fuel cells, ammonia synthesis and petroleum refining.  

Methane purification Carbon molecular sieves also play an important role in the natural gas purification process. By adsorbing carbon dioxide and water in the gas mixture, carbon molecular sieves can effectively increase the methane content in natural gas, thereby improving the combustion efficiency and economic value of natural gas. In addition, carbon molecular sieves can also help separate methane from biogas (such as biogas) so that it can be converted into renewable energy.  

Carbon dioxide capture Carbon molecular sieves are also widely used in carbon dioxide capture and storage (CCS) technology. Due to its unique pore structure and high specific surface area, carbon molecular sieves can separate carbon dioxide from combustion exhaust gas or industrial waste gas by adsorption. This technology is of great significance for addressing climate change and reducing greenhouse gas emissions, especially in high-emission industries such as power plants and cement plants. It has broad application prospects.  

Other gas separation and purification Carbon molecular sieves can also be used to separate other gases, such as ethylene and ethane, propylene and propane, and other olefins and alkane gases. These gas separation processes are usually used in the petrochemical field and play an important role in improving the efficiency and purity of chemical production.

Environmental protection and gas adsorption Due to its excellent adsorption performance, carbon molecular sieve is also widely used in air purification and industrial waste gas treatment. It can adsorb toxic gases in the air such as carbon monoxide, hydrogen sulfide and volatile organic compounds (VOCs), thereby purifying the air and protecting the environment. In the field of water treatment, carbon molecular sieve can also remove organic pollutants and heavy metal ions in water by adsorption.  

As an important gas separation and adsorption material, carbon molecular sieve has broad application prospects. After years of development, its preparation technology has formed a relatively mature process system. However, with the continuous increase in industrial demand, the performance requirements for carbon molecular sieves are also getting higher and higher. In the future, with the advancement of materials science and process technology, carbon molecular sieves will play an important role in a wider range of fields and make greater contributions to solving environmental problems and improving resource utilization efficiency.