Physical Activation Method

The physical method, also known as gas activation method, involves contacting carbonized raw materials with activated gases such as water vapor, flue gas (a mixture of water vapor, CO2, N2, etc.), CO, or air at a high temperature of 800-1000 ℃ to carry out activation reactions. The basic process of the physical activation method mainly includes carbonization, activation, impurity removal, crushing (ball milling), refining and other processes. The preparation process is environmentally friendly with minimal liquid phase pollution. During the preparation process, the disordered carbon atoms and heteroatoms react first with the high-temperature activated gas having oxidizing properties to open previously closed pores and expose the surface of basic microcrystals. Subsequently, the activated gas continues to undergo oxidation reactions with the carbon atoms on the surface of basic microcrystals causing continuous expansion of pore gaps. Some unstable carbons generate CO, CO2,H2 and other Carbon compounds gases due to gasification leading to formation of new pores. Simultaneously tar and unburned substances are removed resulting in obtaining activated carbon products. The developed specific surface area of activated carbon originates from an increase in mesopore and macropore volume which leads to interconnection and connection between macropores,micropores,and mesopores.Due to its relatively simple process,the generated waste gas is primarily composed of CO2.
water vapor, which has less environmental pollution. Moreover, the resulting activated carbon products have a high specific surface area, well-developed pore structure, and a wide range of applications. Therefore, more than 70% of activated carbon manufacturers worldwide use the physical method to produce activated carbon. During the carbon activation process, a large amount of waste heat is generated, which can meet the heat energy requirements for raw material drying, high-temperature steam production from waste heat boilers, and product washing and drying.