Patent ID: 8692034

Claim:
Process for co-producing methanol and ammonia from a hydrocarbon feedstock comprising the sequential steps of: (a) producing a methanol synthesis gas containing hydrogen, carbon oxides and nitrogen by steam reforming the hydrocarbon feedstock in a primary reforming stage and subsequently in an air-blown secondary reforming stage; (b) splitting the methanol synthesis gas into a first methanol synthesis gas stream containing 1-50 vol % of the methanol synthesis gas and a second methanol synthesis gas stream containing 50-99 vol % of the methanol synthesis gas stream, forming a first methanol synthesis gas stream with reduced content of carbon dioxide by passing the first methanol synthesis gas stream through a CO 2 Pressure Swing Adsorption (CO 2 PSA) while bypassing the second methanol synthesis gas stream, withdrawing an off-gas stream containing hydrogen, carbon dioxide, carbon monoxide and methane from the CO 2 Pressure Swing Adsorption, and forming a combined methanol synthesis gas by mixing the first methanol stream with reduced content of carbon dioxide with the by-passed second methanol synthesis stream; (c) catalytically converting the carbon oxides and hydrogen of the combined methanol synthesis gas in a once-through methanol synthesis stage and withdrawing an effluent containing methanol and a gas effluent containing nitrogen, hydrogen and unconverted carbon oxides; (d) producing an ammonia synthesis gas by methanation of unconverted carbon oxides of the gas effluent of step (c) in a catalytic methanation stage and withdrawing an ammonia synthesis gas having a H 2 :N 2 molar ratio of 3:1 without the use of water gas shift and without further use of carbon dioxide removal; (e) catalytically converting the nitrogen and hydrogen of the ammonia synthesis gas in an ammonia synthesis stage and withdrawing an effluent containing ammonia and an off-gas stream containing hydrogen, nitrogen and methane.