Potassium carbonate, the main component of potash and was primarily derived from mined salt potash. The old method was collecting or producing from wood ash (1). Currently, it is mainly synthetically produced by the following three manufacturing processes (2):
1. Obtaining potassium hydroxide first by electrolysis of potassium chloride and then reacting with carbon dioxide. Chlorine (Cl2) and hydrogen (H2) are the byproducts. This is the most used commercial method and also the way to produce potassium hydroxide. The following is the chemical equation for this process:
2 KCl + 2 H2O → 2 KOH + H2 + Cl2
2 KOH + CO2 → K2CO3 + H2O
2. Treating a solution of potassium hydroxide with excess carbon dioxide. 2KOH + 2CO2 = K2CO3
3. Carbon dioxide gas is passed into the potassium hydroxide solution to produce potassium bicarbonate first, then heated. 2KOH + 2CO2 + H2O= 2KHCO3 2KHCO3= K2CO3 + CO2 + H2O
The above three methods are mainly used to produce heavy potassium carbonate, which has a higher density than its light type, the latter can be produced by the ion exchange method: (NH4)2CO3 + KCl
Potassium carbonate hydrate is formed after the process of crystallization and drying from the above solution, which can further be heated above 200°C to obtain potassium carbonate anhydrous.
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