Hou's alkali method
The reaction is carried out in three steps:
1.NH3 + CO2 + H2O → NH4HCO3
2.NH4HCO3 + NaCl → NaHCO3 + NH4Cl
3.2NaHCO3 → Na2CO3 + CO2 + H2O
The carbon dioxide (CO2) produced by the reaction can be recycled, and ammonium chloride (NH4Cl) can be reacted with quicklime to produce NH3, which is reused as a raw material:
2NH4Cl + CaO → 2NH3 + CaCl2 + H2O
The ammonia-alkali method enables continuous production, the utilization of salt is improved, and the quality of the product is pure, so it is called "soda ash", but the biggest advantage is the low cost.
Combined alkali method
The difference between Hou's (combined alkali method) and Soxhlet is the treatment of ammonium chloride. Soxhlet is made by adding quicklime to make ammonia escape, while Hou is adding salt to crystallize ammonium chloride.