Patent GB-128939-A (GB)
IPC: C01C1/04
Abstract: Ammonia is produced from its elements at comparatively low temperatures and under pressure, by a catalyst consisting of a porous cyanamide, or paracyanogen, employed under sufficient pressure to prevent the dissociation or decomposition of the catalyst during the process but not under a pressure greatly exceeding this.  The catalysts mentioned are the cyanamides of calcium, barium, strontium, copper, and silver; and paracyanogen. The catalysts should be prepared under a lower temperature and pressure than those used in the catalytic synthesis.  Calcium cyanamide in suitable form is obtained by dissolving the commercial body in water, removing sulphur by silver nitrate, passing carbonic acid through the filtered solution to produce free cyanamide, dissolving the crystallized free cyanamide in liquid ammonia and adding metallic calcium; or hydrocyanic acid gas may be passed through a solution of calcium in liquid ammonia, forming calcium cyanide which on heating in the catalytic apparatus in the nitrogen-hydrogen mixture blackens and is apparently converted into calcium cyanamide.  Barium and strontium cyanamide are prepared by heating the pure cyanides in nitrogen or ammonia at about 350-450 DEG  C.  Copper and silver cyanamides are prepared by reacting with cupric or silver chloride on a pure solution of calcium cyanamide, the precipitated product being carefully dried in small portions; or by preparing ammonium cyanamide by adding ammonium carbonate or oxalate to a solution of calcium cyanamide, filtering, and adding copper or silver chloride.  Copper or silver cyanamide prepared as described above may be treated with a solution of calcium in liquid ammonia and the ammonia expelled, the product being then heated to about 250-300 DEG  C., when a mixture of copper or silver and calcium cyanamides with free copper or silver is produced.  Dry silver cyanide is heated to 200-300 DEG  C. to form a mixture of silver and paracyanogen.  Paracyanogen may be used when otherwise prepared. Paracyanogen may be dissolved in sulphuric acid and introduced into pumice or other support, after which the support is treated with water to precipitate the paracyanogen and wash away the acid.  The Specification as open to inspection under Sect. 91 (3) (a) describes the catalysts as nitrogenous bodies which may contain carbon, and includes silver and copper nitrides which may be produced by heating the corresponding cyanamides to 500 DEG  C. in a mixture of nitrogen and hydrogen.  Hydrocyanide acid is evolved. This subject-matter does not appear in the Specification as accepted. ALSO: Ammonia is produced from its elements at comparatively low temperatures and under pressure, by a catalyst, consisting of a porous cyanamide or paracyanogen, employed under sufficient pressure to prevent the dissociation or decomposition of the catalyst during the process but not under a pressure greatly exceeding this.  The catalysts mentioned are the cyanamides of calcium, barium, strontium, copper, and silver, and paracyanogen. The catalysts should be prepared under a lower temperature and pressure than those used in the catalytic synthesis, and should be in a porous condition. Calcium cyanamide in suitable form is obtained by dissolving the commercial body in water, removing sulphur by silver nitrate, passing carbonic acid through the filtered solution to produce free cyanamide, dissolving the crystallized free cyanamide in liquid ammonia and adding metallic calcium; or hydrocyanic acid gas may be passed through a solution of calcium in liquid ammonia, forming calcium cyanide which on heating in the catalytic apparatus in the nitrogen-hydrogen mixture blackens, and is apparently converted into calcium cyanamide.  Barium and strontium cyanamide are prepared by heating the pure cyanide in nitrogen or ammonia at about 350-400 DEG C. Copper and silver syanamides are prepared by reacting with cupric or silver chloride on a pure solution of calcium cyanamide, the precipitated product being carefully dried in small portions; or by preparing ammonium cyanamide by adding ammonium carbonate or oxalate to a solution of calcium cyanamide, filtering, and adding copper or silver chloride.  Copper or silver cyanamides prepared as described above may be treated with a solution of calcium in liquid ammonia and the ammonia expelled, the product being then heated to about 250-300 DEG  C. when a mixture of copper or silver and calcium cyanamides with free copper or silver is produced.  Dry silver cyanide is heated to 200-300 DEG  C. to form a mixture of silver and paracyanogen. Paracyanogen may be used when otherwise prepared.  Paracyanogen may be dissolved in sulphuric acid and introduced into pumice or other support, after which the support is treated with water to precipitate the paracyanogen and wash away the acid. The Specification as open to inspection under Sect. 91 (3) (a) describes the catalysts as nitrogenous bodies that may contain carbon, and includes copper and silver nitrides, which may be prepared by heating the corresponding cyanamides to 500 DEG  C. in a mixture of nitrogen and hydrogen. Hydrocyanic acid is evolved.  This subject-matter does not appear in the Specification as accepted.