Industrial processes for chemical separations, including the purification of natural gas and production of nitrogen and oxygen for medical or industrial uses collectively account for nearly 15% of the energy used across the world. These processes account for a corresponding amount of greenhouse gas emissions in the world.
In a new development, researchers at Stanford University and MIT have developed a new type of membrane to undertake separation processes using nearly 1/10th energy and accounting for 1/10th emissions.
The use of membranes for separating chemicals is a much more effective process than distillation or absorption. But permeability has always been a trade-off, how fast gases can penetrate through the substance, and selectively let the desired molecules to pass through while obstructing the others.
Based on ‘hydrocarbon ladder’ polymers, the advent of a new family of membrane materials overcomes this trade-off, and provides high permeability as well as extremely good selectivity.
The findings of the research is published in the journal Science.
Industrially, gas separation is an important and widely used process with a number of uses. It includes eliminating impurities and unwanted compounds from biogas or natural gas, separating nitrogen and oxygen from air for industrial and medical purposes, separating carbon dioxide from other gases for carbon capture, and generate hydrogen for use as a carbon-free transportation fuel.
The advent of new polymer membranes is promising for drastically improving the performance of these separation processes. For example, separation of carbon dioxide from methane, the use of polymer membranes offer five times more selectivity and 100 times more permeability than existing cellulosic membranes for the purpose.
The polymer membranes displayed 100 times more permeability and three times more selectivity for separation of hydrogen gas from methane.
