(WO9408923-A1)      In sepg. an operating process stream consisting essentially of hydrogen, methane, and C3/C4 hydrocarbons which has previously undergone a treatment step e.g. dehydrogenation, and which is then at least subject to a single stage condensation and separation into a C3/C4 hydrocarbon-rich fraction and a H2/CH4 fraction, after which a partial stream of the H2/CH4 fraction is added back to the original, as yet untreated process stream, the H2/CH4 gas fraction withdrawn from the first separator (S1) is divided into two streams (10,17), where the first stream (10) together with the liquid fraction (11) from the bottom of the first separator (S1) is fed, after partial condensation in (W2), to a second separator (S2). The C3/C4 hydrocarbon-rich liquid fraction withdrawn from the bottom of the second separator (S2) together with the second H2/CH4 gas fraction stream (7) from the first separator (S1) are fed into a stripping column (S3). A H2-rich gas fraction of high purity (13) is withdrawn from the top of the second separator (S2) and, after evaporation *in a heat exchanger (W2) against the operating process stream to be cooled, is mixed with the as yet untreated operating stream (2,2a,2b). From the bottom of stripper column (S3) a C3/C4-rich product fraction (20) and from the top of stripper column (S3) a H2-rich gas fraction of lower purity (18), are withdrawn.    USE/ADVANTAGE -   Separation process for reaction products stream containing hydrogen, methane and other low molecular weight hydrocarbons arising from e.g. dehydrogenation of iso-butane to iso-butene for subsequent production of MTBE (me-t-butyl ether). Reduction of soot formation, increasing the capacity and economy of the dehydrogenation reaction by using a low methane content hydrogen recycle stream to provide the necessary ballast for the reactor.    (ZA9307662-A)      In sepg. an operating process stream consisting essentially of hydrogen, methane, and C3/C4 hydrocarbons which has previously undergone a treatment step e.g. dehydrogenation, and which is then at least subject to a single stage condensation and separation into a C3/C4 hydrocarbon-rich fraction and a H2/CH4 fraction, after which a partial stream of the H2/CH4 fraction is added back to the original, as yet untreated process stream, the H2/CH4 gas fraction withdrawn from the first separator (S1) is divided into two streams (10,17), where the first stream (10) together with the liquid fraction (11) from the bottom of the first separator (S1) is fed, after partial condensation in (W2), to a second separator (S2). The C3/C4 hydrocarbon-rich liquid fraction withdrawn from the bottom of the second separator (S2) together with the second H2/CH4 gas fraction stream (7) from the first separator (S1) are fed into a stripping column (S3). A H2-rich gas fraction of high purity (13) is withdrawn from the top of the second separator (S2) and, after evaporation *in a heat exchanger (W2) against the operating process stream to be cooled, is mixed with the as yet untreated operating stream (2,2a,2b). From the bottom of stripper column (S3) a C3/C4-rich product fraction (20) and from the top of stripper column (S3) a H2-rich gas fraction of lower purity (18), are withdrawn.    USE/ADVANTAGE -   Separation process for reaction products stream containing hydrogen, methane and other low molecular weight hydrocarbons arising from e.g. dehydrogenation of iso-butane to iso-butene for subsequent production of MTBE (me-t-butyl ether). Reduction of soot formation, increasing the capacity and economy of the dehydrogenation reaction by using a low methane content hydrogen recycle stream to provide the necessary ballast for the reactor.