| 摘要 |
<p>NaHCO3 is prepd. by reaction at elevated temp. pref. 70-110 degrees C, of amalgam-process NaOH with CO2, in which in a 1st stage NaOH and CO2 react to give a crystallized product contg. Na2CO3H2O, the water of the reaction mixture being simultaneously evaporated the crystallised product is separated from the mother-liquor, which is recirculated to the 1st stage. In the 2nd stage the crystallized product is dissolved and reacted with CO2, the solid NaHCO3 being separated from the mother liquor, which is recirculated as solvent for the 2nd stage. Pref. the second stage is at 20-70 degrees C. The 1st stage may be performed by countercurrent passage of the NaOH and CO2, the temp. decreasing as the reaction-mixture proceeds. Practically complete transformation of NaOH is achieved with minimum supply of external heat.</p> |
