Abstract: An improved process for the separation of gases by selective membrane diffusion or permeation by means of plural stages of membrane separation without increasing the work required by directing a permeant mixture from a second or later stage of separation to a recycle stage of membrane separation to provide a permeate enriched in the desired gas or gases and blending said permeate with the gaseous feed to said second or later stage of separation.

Abstract: Ammonia synthesis processes are disclosed which provide enhanced conversion of hydrogen values to ammonia. In the processes, a purge stream from an ammonia synthesis loop, which purge stream contains ammonia, is contacted at a superatmospheric pressure with the feed side of a separation membrane which exhibits selective permeation of each of hydrogen and ammonia as compared to the permeation of each of methane and argon. A total pressure differential across the membrane is maintained to provide a driving force for the permeation of hydrogen and ammonia through the membrane. A hydrogen-rich permeating gas which contains ammonia is obtained on the permeate exit side of the membrane. The permeating gas is combined with the gas in the ammonia synthesis loop and passed to the ammonia synthesis reaction zone for conversion to ammonia. Ammonia which permeates the membrane can be recovered by the means to remove product ammonia from the gas in the synthesis loop.