GB1358839A - Method for the production of chlorine monoxide gas - Google Patents

Abstract

1358839 Chlorine monoxide PULP & PAPER RESEARCH INSTITUTE OF CANADA 28 July 1971 [5 Aug 1970] 37803/70 Heading C1A Chlorine monoxide is prepared by reacting a highly reactive porous form of a solid alkaline reacting salt of an alkali metal having a surface area within the range 1À0 to 1000 m.<SP>2</SP>/g. with a moist mixture of chlorine and a diluent gas, the chlorine being dry and in substantially stoichiometric amount and the diluent gas being moist air, oxygen, nitrogen or a mixture thereof at a temperature of - 20‹ to + 30‹ C. and removing the chlorine monoxide formed either as a gas or as a solution in carbon tetrachloride. The preferred salt is sodium carbonate which may be prepared by carbonating an aqueous green liquor from the wash water of pulp bleaching operations and containing Na 2 S and Na 2 CO 3 together with minor amounts of Na 2 S 2 O 3 , Na 2 SO 3 and Na 2 SO 4 , drying and pulverizing the so-formed slurry of NaHCO 3 and heating the dried product at 150-300‹ C. Other salts specified include sodium bicarbonate, sodium sesquicarbonate, potassium and lithium carbonates, bicarbonates and sesquicarbonates, sodium and potassium phosphates and sodium and potassium silicates. The salt may be used in stoichiometric or excess amounts. The diluent gas (air, O 2 or N 2 ) should be used in an amount such as to provide a diluent/Cl 2 ratio of at least 77/23 v./v. Ions such as Ni, Co or Cu should not be present as impurities in the alkaline reacting salt since their presence leads to formation of oxygen instead of Cl 2 O. The process may be carried out batchwise or continuously, and it may be associated with a pulp bleaching process. As shown in Fig. 3, dried and ground NaHCO 3 is fed into a fluidized bed calciner 100 where it is heated by a stream of hot CO 2 and H 2 O, the hot gas stream being that evolved by the decomposition of the bicarbonate, heated in a heater 104 and recirculated as fluidizing gas. The porous Na 2 CO 3 is passed to a cooler 108 where it is cooled by air stream 109. The cooled carbonate passes to reactor 112 at a temperature of 150‹ to 500‹ C. where it is fluidized by a stream of gas in line 119, the said stream comprising a mixture of chlorine 113 which is dried at 114 and diluent air, O 2 or N 2 116 the relative humidity of which is controlled between 5% and 95% by apparatus 114. The solid reaction product comprising NaCl with traces of NaClO 3 , Na 2 CO 3 and NaHCO 3 is withdrawn at 120, the gaseous product comprising Cl 2 O, CO 2 and diluent gas passing via line 122 directly to a pulp bleaching reactor 121.