Patent GB-1009784-A (GB)
Title: Production of ammonia and ammonia synthesis and hydrogen-containing gases
Inventor: FRANK SIDNEY MARVIN
IPC: C01B3/02
Filed: 1962-07-18
Abstract: Ammonia synthesis gas is produced by contacting a hydrocarbon with sufficient steam to provide a steam-carbon ratio of at least 3.5 in an indirectly heated first reforming zone maintained at a pressure above 200 p.s.i.g. and at an exit temperature of 1300 DEG  to 1600 DEG F., thus producing an effluent containing hydrogenoid between 2 and 15 mol per cent methane on a dry basis, and contacting effluent from said first reforming zone containing residual and/or added steam with an oxygen containing gas in a second reforming zone maintained under conditions, including a pressure substantially the same as that at which said first reforming zone is maintained, sufficient to reduce the percentage of methane equivalent on a dry basis to less than two and significantly less than said methane equivalent content of the effluent from the first reforming zone.  The effluent from the second zone may be contacted with steam in a shift conversion zone at 600-850 DEG F. and a pressure as above to reduce the CO content to 0.5-2% on a dry basis, CO2 being removed from the product, which then passes through a catalytic methanation zone at 400-800 DEG F. and 200 p.s.i.g. at least (as in the three preceding zones) to produce an effluent containing 1-3% inert gas (A1CH4) on a dry basis, and N2 and H2 in the molar ratio 1 : 3.  Oxides of nickel, cobalt, chromium or molybdenum may be used as catalysts in either the reforming or the shift conversion zones; elemental nickel is also useful as reforming, and tungsten oxide as shift conversion, catalyst.ALSO:Ammonia synthesis gas is prepared in the first stage, and converted to ammonia in the second stage, of the following process.  Hydrocarbon and sufficient steam to provide a steam-carbon ratio of at least 3-5 are mixed in a reaction zone which is held at a pressure above 200 p.s.i.g. and which is indirectly heated to provide an exit temperature of 1300-1600 DEG  F., and product is withdrawn when it contains 2-15% CH4 on a dry basis.  This effluent is contacted with steam and air in a second reaction zone at the same pressure and is withdrawn therefrom at 1600-1800 DEG  F. as an effluent containing nitrogen, hydrogen, carbon monoxide and less than 2% CH4 (all percentages are molar).  The effluent from the second zone is contacted with steam in a shift conversion zone at a temperature from 600-850 DEG  F. and the same pressure as above-mentioned to obtain a gas containing 0.5-2% CO on a dry basis.  CO2 is removed from the product of the shift conversion zone, and the product passes in contact with a catalyst through a methanation zone at a temperature between 400 and 800 DEG  F. and a pressure above 200 p.s.i.g. (as in the three previous zones) to produce an effluent containing 1-3% inert gas (i.e. A and CH4) on a dry basis, and N2 and H2 in the molar proportion 1 : 3.  Ammonia is obtained by mixing this effluent at a pressure of 4000-6000 p.s.i.g. with recycle gas to produce a mixture containing 8-30% inert gas, and contacting the mixture with a catalyst (e.g. Fe) at 4000-6000 p.s.i.g. and 500-1000 DEG  F. Ammonia is separated from the product and unreacted effluent is recycled. Catalysts may be used in the first and second reforming zones and in the shift conversion zone.  Examples of reforming catalysts are Ni, NiO, CoO, Cr2O3, MoO2, while examples of shift conversion catalysts are Fe2O3, NiO, CoO, Cu2O3, MoO2, WO2.