GB190200698A - Improvements in the Manufacture of Nitric Acid and Nitrogen Oxides. - Google Patents

Abstract

698. Ostwald, W. Jan. 9. Nitric acid; nitrogen oxides.-A mixture of ammonia and an excess of air is converted catalytically into nitric acid or higher nitrogen oxides by passing over solid or spongy platinum, or a compound of the two, or over metallic iridium, rhodium, or palladium, or over oxides of heavy metals, such as lead, or over silver, copper, iron, chromium, nickel, or copper oxide. The catalytic material is in every case heated to a red heat. Free nitrogen is also liberated, but its quantity is kept as low as possible. In one form, platinum foil is arranged in alternate series of flat and corrugated strips, the gases passing through the tubular passages formed thereby ; but the foil may be otherwise twisted or made uneven. In other arrangements, several layers of wire netting or of perforated plates may be used, or a resistant material, such as porcelain, may be coated with platinum, or, finally, shavings, chips, balls of wire, or the like may be used as porous layers or bungs. The mixture of air and ammonia may be formed by passing air in contact with a solution containing ammonia, the air flowing in the reverse direction to the ammoniacal solution. The ammoniacal solution may be heated, the heat generated by the catalytic reaction being conveniently employed for this purpose