GB357135A - Improvements in the catalytic manufacture and production of carbon black - Google Patents

Abstract

<PICT:0357135/III/1> <PICT:0357135/III/2> <PICT:0357135/III/3> In the manufacture of carbon black by catalytic thermal decomposition of gaseous or vaporous carbon compounds, such as carbon monoxide or gaseous unsaturated hydrocarbons, the catalyst, in the form of a fine powder, is allowed to fall through the gases, its fall being interrupted repeatedly. For this purpose conveyer worms, bucket wheels, scrapers and shaking sieves or spreaders may be employed. Where vertical decomposition chambers are employed, opposed inclined surfaces down which the catalyst falls may be furnished. In horizontal devices, longitudinal ribs may be formed on the interior of the vessel which lift the catalyst and then allow it to fall. The decomposition chamber may be composed of materials favouring the decomposition, such as copper, manganese-copper or zinc. Other gases and vapours such as water vapour or carbon dioxide, hydrogen, nitrogen, or small amounts of all may be present. As catalysts, there may be employed the metals and oxides of the iron group to which small amounts of activators may be added. Salts of these metals stable to heat, e.g. silicates, phosphates &c., may be used as catalysts, also metals obtained from their carbonyls. As activators may be employed the oxides, carbonates and other alkali or alkaline earth salts, or salts of magnesium, zinc or other metals forming oxides not reducible by hydrogen below 600 DEG C. Atmospheric, increased or diminished pressure may be used and the temperature lies between 300 DEG and 500 DEG C. preferably between 370 DEG and 380 DEG . The mean diameter of the catalyst should be below 0,1 millimetres, preferably 0.01 to 0,0001 millimetres. Separation of the carbon black from the catalyst may be effected by flotation in a liquid or gas, magnetically, by electrical precipitation or by the action of acids. In an example metallic cobalt derived from its carbonyl is contained in an axially-rotated, horizontal cylinder A lined with manganese-copper, gas derived from the carbonization of brown coal and freed from sulphur being led through a pipe D. Longitudinal ribs B raise the catalyst and allow it to fall through the gas, the temperature of the cylinder being maintained at 370-380 DEG C. by an electric heating jacket C. Prior to the introduction of the gas to be decomposed, hydrogen is led over the catalyst for three hours at a temperature of 350 DEG C. Part of the carbon black remains in the cylinder and part is collected in a vessel F. In a second example, the catalyst, consisting of 80 per cent of cobalt, with 10 of nickel, 7 of zinc, 2,5 of calcium oxide, and 0,5 of potash and previously treated with hydrogen, falls from a conveyer P, Fig. 3, through carbon monoxide led in at a pipe F, the internal temperature of the cylinder N being maintained at 380-400 DEG C. by an electric heater R. Interruption of the fall is effected by funnels M and sloping surfaces S carried by a rotating shaft K, scrapers O being provided. Removal of the catalyst from the carbon blacks is effected by treatment with dilute nitric acid at 50 DEG C.