Membrane separation system, and uses thereof

A carbonylation method, comprising:

• combining epoxide, carbon monoxide, carbonylation catalyst and reaction solvent to produce a product stream comprising beta-lactone, residual epoxide, residual carbon monoxide, carbonylation catalyst, and the reaction solvent;
• contacting the product stream with a membrane separation system, wherein the membrane separation system comprises a membrane having a permeate side and a retentate side, and wherein the product stream is contacted with the membrane separation system on the retentate side of the membrane;
• contacting the membrane separation system with a sweep stream on the permeate side of the membrane, wherein the sweep stream comprises solvent saturated with one or more components of a feed stream, whereby the sweep stream minimizes flux of the one or more components across the membrane;
• outputting a permeate stream on the permeate side of the membrane, wherein the permeate stream is formed when at least a portion of the feed stream crosses the membrane and joins with the sweep stream, wherein the permeate stream comprises beta-lactone;
• and
• retaining a retentate stream on the retentate side of the membrane, wherein the retentate stream is formed from the remaining feed stream after at least a portion of the feed stream crosses the membrane, wherein the retentate stream comprises carbonylation catalyst and carbon monoxide.