GB737995A - Method for the manufacture of hydrocyanic acid from volatile nitrogen compounds and hydrocarbons - Google Patents

Abstract

Hydrocyanic acid and hydrogen are produced from volatile nitrogen compounds and hydrocarbons by passing a mixture thereof containing at least a half a nitrogen atom per atom of carbon with oxygen in such quantities if at all, as to ensure the reaction remains endothermic, through or around continuously heated metal tubes or elongated chambers made of or coated with catalysts, the reaction taking place on the catalytic surfaces at above 800 DEG C., preferably at 900-1200 DEG C. Catalysts may be metals or alloys of Pt, Ru, Os, Pd, Rh, Ir, Cu, Au, Re, Ta, Nb, V, Mo, or W, as well as one or more oxides of the second or third groups of the Periodic Table, such as Al, Sc, Y, La, Be, Mg. These may be in the form of foils or gauzes, which may in addition to lining the tube walls, project into the tube, or as coatings, or the tubes may be provided with ceramic layers or inserts which may themselves be catalytic or suitably impregnated. The gas mixture may be passed through the tubes at a linear speed of more than 5 metres per second. The preferred apparatus consists of a bundle of tubes, vertically or horizontally arranged in a heating furnace, the tubes having individual flexible connections and lead-in pipes of smaller diameter which enable the gas to be fed to and withdrawn from the hottest parts of the tubes. Cooling devices may be arranged externally of the heating chamber. The tubes may be heated electrically, by irradiation or by heating gases. According to an example, ammonia and methane in a volumetric ratio of about 1 : 1 were passed through an externally heated heat resistant steel tube lined with a platinum foil containing 10 per cent ruthenium. The rate of flow employed at reaction temperatures between 950 DEG and 1150 DEG C. was from 6 to 60 kilograms of ammonia per day using a 10 mm. diameter tube or 30 to 240 kilograms per day for a 60 mm. diameter tube. Industrial gas mixtures may be used containing as well as ammonia and methane, hydrogen or nitrogen contaminants.