Patent GB-140439-A (GB)
Title: Improvements in and relating to the production of ammonia
IPC: C01C1/04
Filed: 1920-03-17
Abstract: Ammonia is prepared by passing a mixture of nitrogen and hydrogen over a catalyst consisting of a mixture of an alkali or alkali earth metal cyanamide and a nitride-forming metal; such metals are iron, manganese, cobalt, ruthenium, osmium, vanadium, columbium, and tantalum, and as cyanamides those of calcium, barium, strontium, or potassium may be employed.  It is not essential that the cyanamide should be initially present as such, but may be formed during the course of the process, being introduced in the form of carbide or cyanide; and the nitride-forming metal may be added as such or as a compound such as a nitride, ferrocyanide or ferricyanide, or as a compound containing a plurality of nitrogen-carriers such as manganese ferrocyanide, ferric cobaltocyanide, or manganese-iron cobaltocyanide.  The process may be carried out at atmospheric pressure, although increased yields are obtained by employing higher pressures, for example, 10 atmospheres; and it is preferred to employ a nitride-forming metal such that the process may be carried out at a temperature below 600 DEG  C., and above 400 DEG  C., and preferably at about 450 DEG  C.  The materials constituting the catalyst are preferably purified or prepared as follows:-Calcium cyanamide, by dissolving the commercial products in water, treating with sufficient silver nitrate solution to precipitate sulphur, and then with carbonic acid to precipitate cyanamide, which is dissolved in liquid ammonia and reconverted into calcium cyanamide by adding metallic calcium; calcium carbide, by passing acetylene through a solution of calcium in liquid ammonia -such carbide has the formula CaC and gives ethylene when treated with water; calcium cyanide, by passing hydrocyanic acid gas through a solution of calcium in liquid ammonia. The materials for the catalyst may be briquetted together by treating with a solution of potassium cyanide in liquid ammonia.  The Specification as open to inspection under Sect. 91 (3) (a) included also a process in which a cyanamide was employed alone in conjunction with the application of pressure, for example 100 atmospheres.  This subject-matter does not appear in the Specification as accepted.ALSO:Ethylene is obtained by treating with water calcium &c carbides of the formula CaC.ALSO:Calcium cyanamide in a pure condition is prepared by dissolving the commercial product in water, treating with sufficient silver nitrate solution to precipitate any sulphur, and then with carbonic dioxide to precipitate cyanamide which is afterwards dissolved in liquid ammonia and reconverted in calcium cyanamide by adding metallic calcium.  Calcium cyanide in a fine condition and as a white flocculent powder is prepared by passing hydrocyanic acid through a solution of metallic calcium in liquid ammonia.  Carbides, particularly calcium carbide, of the formula CaC, and which give ethylene when treated with water, are prepared by passing acetylene through a solution of calcium in liquid ammonia.  Reference has been directed by the Comptroller to Specification 143,550, [Class 1 (i), Chemical processes &c.]