GB291043A - Process of making absorptive carbon and product thereof - Google Patents

Abstract

291,043. Carbide Carbon Chemicals Corporation, (Assignees of Ray, A. B.). May 25, 1927, [Convention date]. Carbon.-In the preparation of activated carbon, non-coking coals of a bituminous or subbituminous nature are impregnated with an aqueous solution of a carbonizing agent, heated to dryness and then calcined at temperatures upwards of 600‹ C. The calcined product is cooled, leached with water or dilute acid and dried, or it may be further activated by a treatment at high temperatures under oxidizing conditions, e.g., with superheated steam at 800‹-1000‹ C. Coking coals and lignites may also be employed with suitable pre-treatment such as prolonged heating at 200-300‹ C. under oxidizing conditions, for instance in presence of air, mixed or not with oxygen or nitrogen, or of combustion products, or to an equivalent treatment with solvents or oxidizing agents such as strong nitric acid, sulphuric acid, or moist chlorine. This pretreatment may either precede or follow the impregnation with the carbonizing agent. As suitable carbonizing agents, zinc chloride, phosphoric acid, and potassium sulphide are mentioned. The coal may be granulated, or briquetted before heating. The process may be applied to weathered coals and in general to all coals and coal-like products which are or can be rendered non-coking and to mixtures of non- coking coals with cellulosic materials, peats, lignites and the like. Tar or glucose may be added as a binding agent. Heating may be effected in an internally fired rotating drum, or in an electric resistance furnance, at temperatures above 600‹ C., and preferably between 800‹ and 850‹ C. Oxygen is admitted if phosphoric acid has been used. Reference has been directed by the Comptroller to Specification 230,293.