NOVELTY - Carbon dioxide is separated from a gas stream (101) by providing a first membrane (111) having a first feed side and a first permeate side and is selective for 3C hydrocarbons over methane.    USE - For separating CO2 from a gas stream.    ADVANTAGE - The invented method yields a lighter, sweeter product natural gas stream.    DETAILED DESCRIPTION - Separation of carbon dioxide (CO2) from a gas stream containing CO2, methane and 3C hydrocarbons involves providing a first membrane having a first feed side and a first permeate side and is selective for 3C hydrocarbons over methane; passing the gas stream, under conditions where the gas stream has a CO2 partial pressure of at least 30 psia and a 3C hydrocarbons combined partial pressure of at least 30 psia to the first membrane on the first feed side; withdrawing from the first permeate side a first permeate stream (112) enriched in 3C hydrocarbons compared with the gas stream; providing a second membrane having a second feed side and a second permeate side and is selective for CO2 over methane; passing the first residue stream (112) to the second membrane and across the second feed side; withdrawing from the second feed side a second residue stream depleted in CO2 compared with the first residue stream; withdrawing from the second permeate side a second permeate stream enriched in CO2 compared with the first residue stream; providing a third membrane having a third feed side and a third permeate side and is selective for CO2 over methane; passing the second permeate stream to the third membrane and across the third feed side; withdrawing from the third feed side a third residue stream depleted in CO2 compared with the second permeate stream; withdrawing from the third permeate side a third permeate stream enriched in CO2 compared with the second permeate stream; and withdrawing from the third permeate side, a third permeate stream enriched in carbon dioxide compared with the second permeate stream.    An INDEPENDENT CLAIM is also included for an apparatus for separating CO2 from a gas stream comprising a first compressor having a compressor inlet and outlet lines; cooler positioned in the compressor outlet line for cooling compressed gas passing through the compressor outlet line; a phase separator positioned in the compressor outlet line such that condensed liquids can be removed from compressed, cooled gas; a first membrane separation unit containing a first membrane; a recirculation line connecting the first permeate side and the compressor inlet line; second membrane separation unit containing a second membrane selective for CO2 over methane, and having a second feed and second permeate side, where the membrane separation unit is connected to the first membrane separation unit such that gas can flow from the first feed side to and across the second feed side; a third membrane separation unit containing a third membrane selective for carbon dioxide over a methane and having a feed side and a third permeate side; second compressor connected between the second and third membrane separation units such that gas leaving the second permeate side can be compressed before flowing to the third feed side.    DESCRIPTION OF DRAWING(S) - The figure is a schematic view of a basic of an optional compression, cooling and phase separation of the incoming raw gas stream.    Gas stream (101)    Membrane (111)    Permeate stream (112)    Residue stream (112)    Hydrocarbon dew point stream (117)