GB1154083A - Chemical Process and Product. - Google Patents

Abstract

1,154,083. Treated carbon. STANDARD OIL CO. 7 July, 1966 [12 July, 1965], No. 30513/66. Heading C1A. [Also in Division H1] A porous carbon body is prepared by heating carbonaceous material e.g. petroleum, wood, sodium lignosulphonate, bituminous coal, polyvinylidene chloride, and polyacrylonitrile, in a non-oxiding atmosphere at a temperature in the range between 500-1250‹ C. to produce a char containing occluded non-carbon elements, which char is then oxidized and reduced in any order to remove oxide structures and oxygen containing materials by imposing an electrical potential on the char whilst it is immersed in a fused salt, and cycling the potential between a more positive and a more negative value. The char is preferably shaped into a body before the oxidation and reduction treatment and such shaping may be accomplished by mixing the char with a pitch or resin binder shaping the mix and baking at a temperature in the above range. The fused salt used may be a chloride, fluoride or bromide of an alkali metal, an alkaline earth metal, a metal of Group IIIB of the Periodic Table according to Mendeleeff, or a metal of the rare earth or actinide contraction series, perferably a molten bath of lithium chloride-potassium chloride when the body is charged over the potential range from -0À3 to -3 volts relative to the standard chlorine electrode. If desired the salt absorbed into the body may subsequently be removed from it. Before such desalting, the body has an analysis in the range Na, 10-13% by wt. K, 18-21% by wt. Cl, 29-31% by wt., carbon constituting the balance, and after removal of the salt an analysis of the type C, 87À56% by wt., H, less than 0À10% by wt., Cl, 5À51% by wt., Ash, 1À52% by wt., and 0 (by difference) 5À31% by wt. As shown in Fig. 2, the composition of the present invention may be used as an electrode in an electrical energy storage cell. Container 10 holds a fused melt 11, maintained in the molten state by heating coil 12 insulated from container 10 if necessary, by layer 14, heat loss being reduced by thermal insulating layer 16. Immersed in the melt are electrodes 18, 20 at least one of which is in accordance with the present invention, and spacer 22. Current collectors 24 of graphite or tantalum are placed in intimate contact with the electrodes. If desired the electrode may have been treated by the process of the invention before being placed in the cell, or the electrodes may be treated in situ. In Fig. 3 (not shown), a unitary assembly of two such electrode pairs is illustrated. If desired the first oxidation step of the above oxidation-reduction treatment may be carried out by treating the char in an atmosphere of chlorine the reduction being performed in an electrochemical cell, followed by an oxidation in the said cell.