NOVELTY - Separating methane or nitrogen from fluid mixture containing methane and nitrogen comprises flowing fluid mixture into micro channel separator (100), removing the non-sorbed parts of the fluid mixture from the micro channel separator, desorbing the methane or nitrogen from the sorption medium, and removing the desorbed methane or nitrogen from the micro channel separator. The micro channel separator comprises process micro channels.    USE - For upgrading sub-quality methane gas containing nitrogen and methane from coal mines, landfills, and other sub-quality sources.    ADVANTAGE - The invention does not require capital-intensive operations for product recompression. It provides the inventive process with significant cost advantages. It lowers capital operating costs as compared to membrane separation systems, thus allowing marginal natural gas sources to be economically upgraded and utilized. It also offers a modular approach allowing units to be redeployed that is difficult for equipment intensive processes, e.g. cryogenic distillation and lead oil absorption. It can be operated over a wide range of flow rates making it applicable to numerous applications.    DETAILED DESCRIPTION - Separating methane or nitrogen from fluid mixture containing methane and nitrogen comprises flowing fluid mixture into micro channel separator, removing the non-sorbed parts of the fluid mixture from the micro channel separator, desorbing the methane or nitrogen from the sorption medium, and removing the desorbed methane or nitrogen from the micro channel separator. The micro channel separator comprises process micro channels. The process micro channel comprises sorption medium. The fluid mixture is maintained in the micro channel separator until part(s) of the methane or nitrogen is sorbed by the sorption medium.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of micro channel separator used to separate methane or nitrogen from fluid mixture comprising methane and nitrogen.    Micro channel separator (100)    Micro channel separator core (102)    Header (104)    Process footer (106)    Heat exchange header (108)    Heat exchange footer (110)