Activated carbon is a highly porous carbon with an exceptionally large internal surface area, created by a highly branched network of micro-, meso-, and macropores. This pore structure enables a particularly high adsorption capacity for gases, vapors, and dissolved substances. The production of activated carbon from non-porous, carbonaceous starting materials is called activation. In this process, raw materials such as wood, coal, or coconut shells are activated by treatment with steam or carbon dioxide at high temperatures of 700–900 °C. This process removes unwanted components such as tar or volatile substances and creates pores of varying sizes within the carbon.

The structure of the remaining carbon skeleton is significantly influenced by the chosen starting material. This structure determines both the distribution of pore sizes – from microscopically small pores for molecules to larger cavities – and the mechanical properties of the activated carbon, such as hardness and abrasion resistance. For example, the use of particularly hard raw materials, such as coconut shells, results in an activated carbon with exceptional stability and durability, making it especially suitable for applications with high mechanical stress.

Due to the aforementioned properties, activated carbon, in addition to its function as an adsorbate, is also suitable as a support material for precious metal catalysts due to its high specific surface area (BET method). For example, platinum and palladium applied to activated carbon are used for the hydrogenation of unsaturated hydrocarbons.