Hydrogen production from waste-derived synthesis gas over Ni(x)Fe(3-x)-CeO2 catalyst: optimization of Ni/Fe ratio

Abstract

In this study, the effect of the Ni/Fe molar ratio on the Ni(x)Fe(3-x)-CeO2 catalyst was investigated for the high-temperature water-gas shift reaction, which produces hydrogen from waste-derived synthesis gas. The catalysts were synthesized via a co-precipitation method, using different Ni/Fe molar ratios (0.5:2.5, 1.0:2.0, 1.5:1.5, 2.0:1.0, and 2.5:0.5). The physicochemical properties of these catalysts were analyzed by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), temperature-programmed reduction using hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and H2-O2 pulse analyses to determine their reaction performance. The Ni1.0Fe2.0-CeO2 catalyst exhibited the highest activity (Xco = 88%, T = 500 °C) without any side reactions at a high gas hourly space velocity of 41,823 mL·g−1 h−1, compared to the other catalysts tested, owing to its high oxygen vacancies and oxygen storage capacity (OSC). In addition, when the Ni/Fe molar ratio was higher than 1, a side reaction (methanation) occurred. Therefore, it was concluded that the Ni1.0Fe2.0-CeO2 catalyst is optimal for hydrogen production via the high-temperature water-gas shift reaction from waste-derived synthesis gas.