NOVEL ELECTROCHEMICAL HYDROGEN SEPARATION DEVICE USING PHOSPHORIC-ACID MEMBRANE CELL

State-of-the-art hydrogen separation technologies operate at/or near ambient temperatures and are not considered very effective with gases containing low concentrations of hydrogen (such as coal-gas) and are susceptible to common impurities such as H2S, H2O, and NH3. Energy Research Corporation is developing an alternate, versatile process for hydrogen separation from any hydrogen-containing gas. This novel process involves oxidation of hydrogen at a gas diffusion anode to hydrogen ions, transportation of the ions under applied electrical field to a cathode, and reduction of the hydrogen ions at the cathode to hydrogen gas. The device offers many attractive features, including high hydrogen recovery (> 90%), high product purity (> 99%), tolerance to a variety of impurities, flexible product pressure, efficient operation with very dilute gases, negligible pressure loss, and wide operating pressure range including atmospheric. The feasibility of this electrochemical hydrogen separation device (EHSD) has been demonstrated at ERC using hydrogen concentrations as high as 75% (reformer product) and as low as 10% (process purge). The operating principle, design, and performance (current-potential relationship, product gas purity, effect of feed hydrogen concentration on hydrogen recovery and power requirements) of this process are presented in this paper.