Deblending and purification of hydrogen from natural gas mixtures using the electrochemical hydrogen pump

Abstract

This work evaluates the use of Electrochemical Hydrogen Pumps (EHPs) for H2 deblending from natural gas (NG) grids for use in H2 refuelling stations which need to meet the high ISO 14687-2019-D purity standards. Concentrations of 20, 50 and 80% H2 in either CH4 or NG were tested at current densities of 0.2 and 0.3 A cm−2. Moreover, the impact of adding O2 and O2/O3 bleeds to the inlet EHP feeds were investigated for their effectiveness in mitigating poisoning of the EHP catalysts. The CH4 concentration requirement of <100 μmol mol−1 was met using NG at 0.3 A cm−2 (20–80% H2) or with 80% H2 at 0.2 A cm−2; however, the CO2 limit of <2 μmol mol−1 could not be met, due to the high permeability of CO2 in Nafion®. Moreover, the other hydrocarbon concentrations limit of <2 μmol mol−1 could be met when operating with 80% H2 in NG at 0.3 A cm−2. Additionally, the EHP demonstrated low energy consumption, particularly at 0.2 A cm−2 ranging from 3.5 to 12.5 kWh kgH2−1.