Patent GB-446892-A (GB)
Title: Non-structural activated carbon and process for the production thereof
IPC: C01B32/336
Filed: 1934-08-01
Abstract: Active carbon for use in finely divided condition is prepared by mixing a finely divided inactive carbon, active carbon, or carbonaceous material yielding an active carbon char, with an aqueous emulsion of a binder which chars on heating, consisting mainly of hydrocarbons, one or both ingredients of the mixture being adapted to form active carbon, carbonizing the mixture without first compressing it, and activating the product.  In a modification, the carbon is mixed directly with the solid pitch or other binder, and an aqueous emulsion of oil, tar, anthracene oil, or creosote oil, or other organic liquid is added which will dissolve, disperse or flux with the binder.  This emulsion is preferably of the oil-in-water type. The active carbon may be a vegetable charcoal, carbon from natural gas, or it may be formed within the mixture during carbonization by using freely divided organic substances such as straw, hulls, or wood.  The binder may be prepared by emulsifying tars and pitches obtained by distinctive distillation, e.g. pitches from the tars of wood, bones, coal, oil shales, lignite, peat, straw, hulls, bitumens, water gas, and oil gas; oil pitches including those obtained in distillation and cracking of animal, vegetable, and petroleum oils; pitches from the destructive distillation of stearin, palm oil, bone fat, fat waste, other animal and vegetable substances, natural bitumen, asphalt, asphaltites, coal, peat, and lignite. The preferred binder is pitch obtained as a residue from the distillation of "soluble tar," which is itself the residue from the distillation of the aqueous or tarry pyroligneous acid layer formed in the destruction distillation of hard wood.  Soluble wood-tar or the pitch therefrom may be blended with settled wood-tar, coal-tar, or the corresponding pitches.  Mixtures specified for carbonizing are hardwood char, with or without active carbon from natural gas, and wood-tar pitch or coal-tar pitch; petroleum coke and wood-tar pitch. Hardwood chars specified are those from maple, oak, hickory, and birch.  In one procedure, ground hard pitch is suspended in water containing a protective colloid, e.g. an alkaline casein solution; anthracene oil, creosote oil or other coal-tar distillate is emulsified with a similar protective colloid; the pitch suspension and the oil emulsion are mixed forming an emulsion of soft pitch, and this emulsion is mixed as a binder with a thick paste formed from the finely divided carbon and water containing a protective colloid. Water is separated, by filtration if necessary, and the residue is dried at 88--122 DEG  C., or is fed directly into the carbonizing furnace.  The emulsified binder may be stabilized by ammonium tannate.  Carbonization may be effected by heating in a rotary drum furnace for 20 to 60 minutes at 480--985 DEG  C., and preferably at 650--820 DEG  C., with the material in thin layers.  Activation may be effected by heating in the presence of steam, air chlorine, flue gas or other activating gas for 1 to 5 hours at 650--985 DEG  C. The product may be treated with water or dilute acid to remove ash.  the mixture of carbon and binder may be mixed also with calcium or magnesium carbonate or oxide, a finely divided metal, oxide or salt, then added substance being removed from the activated carbon by treatment with water or dilute acid.  There may also be added substances which volatilize or react with the carbonaceous material during the treatment, such as zinc chloride or phosphoric acid.