Activated carbon specific surface area analyzer - Database & Sql Blog Articles

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Activated carbon, also known as carbon molecular sieve, is a black porous solid carbonaceous material. Ordinary activated carbon has a specific surface area of ​​500--1700 m 2 /g, and has strong adsorption performance, and is an industrial adsorbent with extremely wide application. It relies on its developed pore structure and surface area to adsorb some pollutants into the pore structure. The larger the surface of the activated carbon and the more developed the pore structure, the stronger the adsorption capacity.

The main characteristics of activated carbon:

Adsorption characteristics

Activated carbon is a very fine carbon particle with a large surface area, and there are finer pores in the carbon particles - the capillary. This capillary has a strong adsorption capacity and is sufficiently in contact with gas (impurities) because of its large surface area. When these gases (impurities) hit the capillary, they are adsorbed and purify. The surface area of ​​activated carbon is very important. The specific surface area detection data of activated carbon is true and reliable by the BET method. The specific surface area measurement standard developed at home and abroad is based on the BET test method. Please refer to the Chinese national standard. (GB/T 19587-2004) - Method for determining the specific surface area of ​​solid materials by gas adsorption BET principle. The JW-DA specific surface area tester is an instrument that can truly realize the BET detection function (both direct contrast method). The more important JW-DA specific surface area tester is the only fully automated and intelligent surface area detection equipment in China. A foreign customized equipment has been exported to Japan, the United States and other countries, the stability is super good, the software is designed and developed jointly by China and Japan, very humanized, and the test results are highly accurate.

Adsorption capacity of activated carbon for each gas (unit: ml/cm3):

H2, O2, N2, Cl2, CO2

4.5, 35, 11, 494, 97

Catalytic properties

Activated carbon is accompanied by a catalytic reaction in many adsorption processes, exhibiting catalyst activity. For example, activated carbon adsorption of sulfur dioxide is catalytically oxidized to sulfur trioxide. Since activated carbon has a specific surface oxygenate or complex, it has catalyst activity for various reactions, such as chlorine gas and carbon monoxide to generate phosgene.

Since a complex is formed between the activated carbon and the support, the complex catalyst greatly increases the catalytic activity, for example, the activated carbon carrying the palladium salt, even if the catalyst without the copper salt is present, the oxidation reaction of the olefin can be catalyzed. And the speed is fast and the selectivity is high.

Since activated carbon has a developed pore structure, a large internal surface area, and good heat resistance, acid resistance, and alkali resistance, it can be used as a carrier for the catalyst. For example, in the reaction of hydrogenation, dehydrocyclization, isomerization or the like in organic chemistry, activated carbon is an excellent carrier for platinum and palladium catalysts.

Mechanical properties

(1) Particle size: A set of standard sieve sieving method was used to determine the weight of activated carbon remaining in and passing through each sieve to indicate the particle size distribution.

(2) Static density or bulk density: the weight of the activated carbon per unit volume of the dietary pore volume and the interparticle void volume.

(3) Bulk density and particle density: the weight of the activated carbon per unit volume of the dietary pore volume without the intergranular void volume.

(4) Strength: the crushing resistance of activated carbon.

(5) Abrasion resistance: that is, wear resistance or anti-friction performance.

These mechanical properties directly affect the application of activated carbon, for example: density affects the size of the container; the thickness of the powder affects the filtration; the particle size distribution of the carbon affects the fluid resistance and pressure drop; the fracture affects the service life of the activated carbon and the regeneration of the waste carbon.

Chemical properties

In addition to physical adsorption, adsorption of activated carbon also involves chemical adsorption. The adsorption of activated carbon depends on both the pore structure and the chemical composition.

Activated carbon not only contains carbon, but also contains a small amount of chemically bonded, functional group-starting oxygen and hydrogen, such as carbonyl, carboxyl, phenols, lactones, terpenes, ethers. Some of the oxides and complexes contained on these surfaces are derived from derivatives of raw materials, some of which are formed by the action of air or water vapor upon activation and activation. Surface sulfides and chlorides are sometimes formed. In the activation, the minerals contained in the raw materials are concentrated into activated carbon to become ash, and the main components of the ash are alkali metal and alkaline earth metal salts, such as carbonates and phosphates, which can be washed by water or pickled. reduce.