How to separate butane from air? I work in a manufacturing company specializing in polyethelene foam and I have been struggling to separate butane from air in our warehouse during curing period where all the butane gas used to make our product is just released in the air. I have been thinking of ways how to separate and recycle the butane? Can someone help me?
Butane has pretty high  boiling point (around $\ce{0 °C}$). This means, that just cooling air to $\ce{-30 °C}$ should condense a lot (if not all) of butane from it.

However, as I guess, most of butane used in foam production remains in the foam, otherwise the foam would collapse.  So, it is very possible that there is not much to recycle in air itself. The gas, of course, will be released eventually, but only when foam itself is destroyed.