GB874589A - Process for the manufacture of chlorine dioxide - Google Patents

Abstract

<PICT:0874589/III/1> Chlorine dioxide is prepared in a continuous process by reacting an aqueous solution of H2SO4 containing an alkali, or alkaline earth, metal chlorate with SO2 in a first stage to convert 70-95% of the chlorate, and reacting the residual chlorate in the solution discharged from the first stage with SO2 in a second stage. Chlorates may be NaClO3, KClO3, Ca(ClO3)2, Ba(ClO3)2, or Sr(ClO3)2. 35-60% H2SO4 and chlorate are charged at 3, 4 into first reactor 1, while air or inert gas containing 0.5-10% SO2 is introduced through distributer 5. Conditions in the first reactor are adjusted, at 15-60 DEG C., so that the chlorate concentration is maintained above 1%, preferably 1.5-4%, and 70-95% of the chlorate is reacted at the rate 0.3-0.5 mol. ClO31 per hr. per litre solution. The solution flows at 2 into second reactor 7 also supplied with SO2-containing gas through distributer 8, and conditions in the second reactor are adjusted, at 15-60 DEG C., so that the concentration of chlorate is maintained below 1, preferably 0.15-1.0%, which is reacted at the rate 0.01-0.1 mol. ClO31 per hour per litre solution. The ClO2 gases from both reactors are withdrawn at 6 and exhausted solution at 10.