method for recovering chlorine from electrolytic hydrogen chloride or hydrochloric acid solution.

摘要

Mercuric chloride is made by reacting aqueous hydrochloric acid with oxygen and metallic mercury at a temperature from 40 DEG C. to the boiling point of the HCl solution in the presence of a catalyst. The catalyst may be a salt of a metal exerting at least two valencies such as FeCl3 or CuCl2 used alone or in admixture with one another or with another metal compound such as PdCl2, CoCl2, Na2MoO4 or NaVO3. Other possible catalysts are TiCl4 or KReO4. MnSO4 may be added to FeCl3. The preparation of dissolved mercuric chloride comprises a step in the recovery of Cl2 from HCl by electrolysis (see Division C7). U.S.A. Specification 2,468,766 is referred to.ALSO:Clorine is recovered from aqueous rydrocloric acid by reacting the acid with oxygen and metallic mercury at a temperature from 40 DEG C. upto boiling point of the HCl solution in the presence of a catalyst to form dissolved mercuric chloride and then electrolysing the HCl solution containing mercuric chloride at a current density below the current density at which evolution of hydrogen at the cathode occurs to form Cl2 and Hg. The resulting Hg is returned to react with more HCl and O2 whereas the electrolyte resulting from the electrolysis, which has a low content of HgCl2 is returned to the process and may be used as an absorbent for HCl gas to form HCl solution. Water formed during the oxidation of the Hg is withdrawn from the system, e.g. by evaporation at the oxidation stage or by evaporation using heat produced in the electrolytic cell. The catalyst may be a salt of a metal exerting at least two valencies such as FeCl3 or CuCl2 used alone or in admixture with one another or with another metal compound such as PdCl2, CoCl2, Na2MoO4 or NaVO3. Other possible catalysts are TiCl4 or KReO4. MnSO4 may be added to FeCl3. For the electrolysis, a graphite anode and a cathode of graphite, mercury or a metal wettable by mercury such as Cu, Ni or "Morel" (Registered Trade Mark) metal may be used. The Hg may trickle down an inclined or vertical surface. The cathode may comprise metal discs or a metallic band moved through the electrolyte and a mercury sump. U.S.A. Specification 2,468,766 is referred to.