High-efficient removal of Oxygen(O2) impurity from H2 flow on nickel-manganese Oxide: Regulating the exposed crystal plane, structure-activity relationship and determination of active sites

The presence of oxygen (O2) impurity in hydrogen produced by water electrolysis can pose safety hazards when hydrogen is used as a power source. Therefore, oxygen (O2) impurities must be removed from H2 flow to meet the strict purity requirements. In this work, nickel manganese oxide is applied to remove oxygen from H2 flow. It is synthesized via the co-precipitation method using different precipitants, manganese and nickel precursors. The results of the oxygen removal test show that NiMn-4 catalyst, prepared using oxalic acid, manganese acetate and nickel nitrate as the precursors, has the best performance in removing oxygen impurities from the hydrogen flow. The catalyst could retain an oxygen removal efficiency of nearly 70 % at the reaction temperature of 80 degrees C. Also, XRD, Raman spectra and HRTEM analysis results show that the crystal phase of NiMn-4 (Ni6MnO8) exhibits much stronger crystallinity than the other catalysts and has (400) and (222) planes of Ni6MnO8. H2/O2-TPD and H2-TPR analysis results indicate that NiMn-4 catalyst has much more adsorbed oxygen species, overflow hydrogen and hydrogen consumption at per specific surface area compared to the other catalysts. The XPS results of Ni2p and O1s imply that there is much higher valence of Ni (Ni3+).