Activated carbon There are two production methods, chemical activation method and physical activation method.
1. Chemical activation method
The chemical activation method is to prepare activated carbon through carbonization, activation, recovery of chemicals, rinsing, drying and other processes after evenly mixing various carbon containing raw materials with chemicals at a certain temperature.
Phosphoric acid, zinc chloride, potassium hydroxide, sodium hydroxide, sulfuric acid, potassium carbonate, polyphosphoric acid and phosphate ester can all be used as activation reagents. Although different chemical reactions occur, some have erosive, hydrolysis or dehydration effects on raw materials, and some have oxidation effects, these chemicals can all promote the activation of raw materials to a certain extent. The commonly used activator is phosphoric acid Zinc chloride and potassium hydroxide.
The activation principle of chemical activation method is not very clear. It is generally believed that chemical activator can erode and dissolve cellulose, and can decompose and separate hydrogen and oxygen contained in hydrocarbons in raw materials to H2O, CH4 and other small molecules escape, resulting in a large number of pores. In addition, chemical activator can inhibit the formation of tar by-products and prevent tar from blocking the pores generated during pyrolysis, thus improving the yield of activated carbon.
In China, powdered activated carbon produced by wood phosphoric acid process has achieved large-scale, automatic and clean production, and the overall technology has reached the international leading level.
2. Physical activation method
Physical method, also known as gas activation method, refers to the process of converting carbonized raw materials into The process of activating reaction by contacting with water vapor, flue gas (mixture of water vapor, CO2, N2, etc.), CO or air and other activated gases at a high temperature of 800~1000 ℃. The basic process of physical activation mainly includes carbonization, activation, impurity removal, crushing (ball milling), refining and other processes. The preparation process is clean and the liquid phase pollution is less.
