Activated Carbon from CPL Carbon Link: Production Operations and Processing Techniques

1.2 Production Operations and Processing Techniques

There is a wide variety of production and processing techniques used in the manufacture of activated carbons, these are dependent on;

Nature and type of raw material available
Desired physical form of the activated carbon
Characteristics required for the intended application

A Coconut Shell factory in Asia

The activation techniques which are principally used by commercial production operations are;

Chemical Activation

This technique is generally used for the activation of peat and wood based raw materials. The raw material is impregnated with a strong dehydrating agent, typically phosphoric acid (H3PO4) or zinc chloride (ZnCl2), mixed into a paste and then heated to temperatures of 500 - 800°C to activate the carbon. The resultant activated carbon is washed, dried and ground to powder. Activated carbons produced by chemical activation generally exhibit a very 'open' pore structure, (commonly refered to as 'Macroporous'), ideal for the adsorption of large molecules.

Steam Activation

CarboTech Aktivkohlen GmbH
activated carbon plant

This technique is generally used for the activation of coal and coconut shell raw material, which is usually processed in a carbonised form. Activation is carried out at temperatures of 800 - 1100°C in the presence of steam.

Initially, gasification of the carbonised material with steam occurs; a reaction known as the Water-Gas reaction:-

C + H20 -> CO + H2 -175,440 kJ/(kg mol)

This reaction being endothermic, temperature is maintained by partial burning of the CO and H2 formed:-

2CO + O2 -> 2CO2 +393,790 kJ/(kg mol)
2H2 + O2 -> 2H2O +396,650 kJ/(kg mol)

The air is added so as to burn the gases without burning the carbon.

The resultant activated carbon is graded, screened and de-dusted.

Activated carbons produced by steam activation generally exhibit a 'fine'to 'medium' pore structure, (commonly refered to as 'Microporous and Mesoporous'),ideal for the adsorption of compounds from both the liquid and vapour phase.

CPL Carbon Link specialises in the use of steam activation for the production of coconut shell and coal based activated carbons.

Experience gained over many years of operation is used to ensure that products are of uniform quality for consistent high performance.