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. Electrochemical pumps can effectively purify and compress hydrogen for subsequent use in energy and industrial applications but struggle with low hydrogen concentrations. Here the authors present an electrochemical pump based on an ion-pair membrane that can produce high-purity hydrogen from a 10% blend in methane.