GB496721A - Process for the removal or conversion of one or more of the constituents of a gaseous mixture - Google Patents

Abstract

496,721. Electrolysis; gas-purifying processes. GAS LIGHT & COKE CO., and DUDDEN, W. R. June 1, 1937, No. 15187. [Class 41] [Also in Group XII] Impurities such as nitric oxide or hydrogen sulphide in town gas or sulphur dioxide in waste flue gas are removed or converted by bringing the gas preferably at atmospheric temperature and pressure into contact with the anode of an electrolytic cell at which oxygen is being evolved. A voltage not greater than 5 is applied across the cell. A lead anode may be employed in a dilute solution of sulphuric acid or sodium sulphate, an iron or nickel anode in a dilute solution of caustic soda, or a platinum anode in any of these baths. In the apparatus shown in Fig. 1, the anode consists of a platinum wire 11 wound over a porous fireclay pot 7 containing sulphuric acid (5 per cent by volume) and enclosing a lead cathode 10. Coal gas is fed upwards through a passage formed by a glass spiral 8 mounted between the pot 7 and the container 1. Electrolyte percolating through the pot 7 leaves by a liquid seal 9 provided with a vent 13. The apparatus shown in Fig. 3 comprises lead pipes 41, 42 separated by insulators 43, 44, and packed with lead wool separated into two parts by a layer of porous asbestos or coarse sand 47 to form the electrodes, the anode mass 46 being supported on a spring-pressed perforated plate 48. A small stream of 10-25 per cent sulphuric acid is introduced by a pipe 51 and a faster stream of water by a pipe 52 ; the liquid percolating through the electrodes overflows at 55. The gas is passed downwardly through the cell. Lead nitrate is formed at the anode and reacts with the electrolyte to form lead sulphate and nitric acid. The process may be applied to the quantitative determination of nitric oxide in town gas, a platinum anode being employed in this case and the nitrogen peroxide produced determined with Griess reagent. The Provisional Specification describes also an apparatus similar to that shown in Fig. 1 in which the gas passage is formed solely by a spiral anode fitted closely between the porous pot and the container.