Oxalic acid prepn. - by reductive oxalation of carbon di:oxide in electrolysis cell with an electronegative metal anode

摘要

In an electrochemical process for the prodn. of oxalic acid, CO2 is led up to an electrically (semi)conductive cathode in an electrolysis cell, and is reduced by oxalation. The cell contains a single, non-partitioned, aprotic electrolyte and the anode is composed of an electronegative metal or alloy giving metal ions which form insoluble oxalates with oxalate ions. The resulting insoluble oxalate is sepd and treated with a strong acid to form oxalic acid. Pref the anode is of Zn and H2SO4 is used to liberate the oxalic acid. The metal salt or sulphate formed as by-prod. is pref. subjected to electrolytic treatment to recover the metal. The operations may be carried out continuously in a recirculation process which need virtually no input of chemicals. The process overcomes the drawbacks of prior art electrolytic oxalic acid prodn processes, and does not require the use of compartmentalised electrolysis cells. The process can be operated continuously on a prodn scale.