Electrochemical pumps based on ion-pair membranes for separation of hydrogen from low-concentration mixtures

Abstract

Producing pure, compressed hydrogen from gas mixtures is a crucial, but expensive, aspect of hydrogen distribution. Electrochemical hydrogen pumps offer a promising energy-efficient solution, but struggle with gas mixtures containing less than 20% hydrogen. Here we show that electrochemical hydrogen pumps equipped with phosphate-coordinated quaternary ammonium ion-pair polymer membranes can overcome this challenge. By using a protonated phosphonic acid ionomer and selective cathode humidification, mass transport of the device is enhanced, boosting hydrogen production from low-concentration hydrogen gas mixtures. A tandem ion-pair electrochemical hydrogen pump system achieves high-purity hydrogen (>99.999%) from a 10% hydrogen–methane mixture with nearly 100% faradaic efficiency and hydrogen recovery. A techno-economic analysis reveals that electrochemical hydrogen pumps can reduce hydrogen delivery costs by up to 95% and energy consumption by up to 65% by allowing the use of existing natural gas pipelines, compared to traditional pressure swing adsorption and mechanical compression techniques.