Methods and systems of enhanced carbon dioxide recovery

Methods and systems of enhanced carbon dioxide recovery from an inlet gas stream are provided, by introducing the gas stream to one or more membrane-based separation units to produce a permeate byproduct gas stream having increased concentration of carbon dioxide compared to the inlet gas stream and then introducing the permeate byproduct gas stream to one or more pressure swing adsorption units or trains to enhance recovery of hydrocarbons, such as methane, lost in the byproduct stream and to produce a substantially pure carbon dioxide stream, while minimizing process compression and eliminating process heat for process regeneration. The methods introduced herein are for enhancing product recovery by enhancing carbon dioxide recovery from gas streams with pressures greater than atmospheric conditions. Further refinement to the methods would be the introduction of hydrogen sulfide polishing units within the process to produce product that meets or exceeds sales quality specifications.