Combining electrochemical hydrogen separation and temperature vacuum swing adsorption for the separation of N2, H2 and CO2

Abstract

In biohydrogen processes, H2 is often present in gas mixtures with CO2 and N2. Therefore, we present a separation process that combines electrochemical hydrogen separation (ECHS) and amine-based temperature vacuum swing adsorption (TVSA). Such a separation process does not require the compression of the bulk feed. For the ECHS, a trade-off between cell potential, i.e. power consumption, and stack size, i.e. investment costs, existed. The optimal cell voltage laid in the range of 0.1–0.2 V resulting in costs of 0.37 €/kgH2. Equivalently, the energy consumption and throughput for the TVSA must be balanced. The optimal desorption pressure and temperature of 0.025 bar and 100 °C resulted in costs of 2.30 €/kgH2. Thus, the total costs for the separation process were 2.67 €/kgH2, which are in the range of the separation costs of a binary H2/CO2 mixture with a similar H2 feed fraction.