GB704810A - Improvements in or relating to the production of activated carbon, catalysts or catalyst carriers - Google Patents

Abstract

In producing materials with surface active properties, especially activated carbon, catalysts, or catalyst carriers, from carbonaceous substances, such as wood, peat, coke, brown or mineral coal, which are conducted through the activating zone by means of an activating or inert gas, the requisite heat for activation is partly or wholly transmitted to a mixture of the substances to be activated and the gaseous activating agents and/or other activating agents by means of moving heat transferring solids and the heat transferring solids are subsequently separated from the activated product, e.g. by difference in specific gravity. The heat carriers, which may be reheated and reused after giving up utilisable heat, may be ceramic substances, e.g. alumina or other metal oxides, quartz, refractory silicates, metals, silicon, silicon carbide, or carbonaceous substances, e.g. coke, coal, or graphite, preferably of specific heat exceeding 0.3, moving countercurrent, cocurrent, or transverse current, or any combination of these, to the gas carrying the material to be activated. Heat remaining in the heat carrier may be used for preheating. If a carbonaceous heat carrier is used part may become activated and may be separated from the non-activated part, which is reused. The heat carrier may be heated outside the treatment zone by fuel combustion, or, if combustible materials are used as heat carriers, these may be heated by partial combustion outside the treatment chamber. Heat may also be supplied by fuel combustion during the activation and the gases generated in the activation may be used for this purpose. The material to be activated, which may be pre-dried, may be carried in suspension in activating gases, e.g. carbon dioxide or steam, or may form a fluidized bed with the heat carrier passing therethrough, and part or all of the activated carbon may be treated more than once. The material to be activated may be impregnated with chemical activating agents, e.g. alkali metal hydroxides or salts, zinc chloride, or phosphoric or sulphuric acids, and by use of inert gas or activating gas at 200-500 DEG C., or activating gas at 500-600 DEG C. or above chemical activation alone or a combination of chemical and gas activation may be effected. The activated product may be separated in cyclones, with or without a simultaneous division into fractions on grain size by screening, on ash content, or on specific gravity or bulk density by elutriation, or the division into fractions may be effected after separation. The activated product or the fractions may be after treated with distilled water, acids, alkalies, or solution of salts of alkali, alkaline earth or heavy metals, or with impregnating chemicals for specified purposes, e.g. iodine, alkalies, copper salts, phosphoric acid, wetting agents, or fats or oils. The activated product may be partly or wholly ground, agglomerated with a binder with or without impregnating chemicals and subjected to further activation, or classified by electrostatic precipitation. Specifications 676,391 and 679,095 are referred to.