Efficient gas separation

A new polymer developed by researchers at Cardiff may lead to more efficient large-scale separation of gas mixtures for chemical engineering and energy generation.

Gas separation is crucial for many industrial processes including obtaining nitrogen or oxygen from air and purifying natural gas or hydrogen. Currently, the most energy efficient method for separating gases involves polymer membranes, however, most polymers either let gases pass through slowly (i.e. have low permeability) or are not selective towards one gas over another. Gas separation would be cheaper and use less energy if polymer membranes could be made both highly permeable and selective.

A team from the School of Chemistry reports in the journal Science a new polymer that efficiently separates gas mixtures based on the different sizes of the gas molecules. The polymer's molecular structure is very contorted so that it cannot fill space efficiently, therefore leaving gaps for small gas molecules to move through quickly. However, the transport of larger gas molecules is hindered by the polymer's extreme rigidity so that it acts as an

The Cardiff's team's collaborators at the Institute on Membrane Technology, ITM-CNR, Italy, confirmed that membranes prepared from the polymer are both highly permeable to gases and demonstrate remarkable selectivity for smaller gases such as hydrogen or oxygen over larger gases such as nitrogen or methane.