GB383402A - A process for the treatment of carbon obtained by the decomposition of a carbon-containing gas in the presence of a metal containing catalyser - Google Patents

Abstract

Carbon obtained by the catalytic decomposition with metal or metallic compound of a carbon-containing gas, e.g. carbon monoxide or a hydrocarbon, is rendered fit for use as a pigment by connecting the metal or metallic carbide resulting from the catalyst into a dark-coloured compound which harmonizes with the carbon. In the case of carbon obtained by the use of ferric oxide as a catalyst, iron carbide remaining is treated with an acid, such as tannic or gallic acid, or with a phenol, thus producing the desired dark-coloured compound. To convert the carbides to Prussian blue, the carbide is first treated with an acid, then with a cyanide and finally with an oxidizing agent. The catalysts described are iron, ferric oxide and oxalate, nickel, nickel oxalate, cobalt and cobalt oxalate. In the case of nickel and cobalt, the carbides formed may be converted to dark-coloured sulphides. In an example, 100 kilogrammes of carbon containing 5 per cent of iron are heated with 9,8 kilogrammes of sulphuric acid diluted with enough water to moisten the whole of the carbon. The mass is mixed with a concentrated solution of potassium ferrocyanide and potassium chlorate and dried. The potassium salts may be removed by washing with water.