The investigation of non-noble metal doped mesoporous cobalt oxide catalysts for the water-gas shift reaction

In this study, we report an investigation of the low temperature water-gas shift (LT-WGS) reaction over a series of non-noble metal doped (Me = Mn, Fe, Co, and Ni) mesoporous Co₃O₄ catalysts. The effect of metal dopants on the structure and reducibility of the mesoporous Co₃O₄ oxide was examined using X-ray diffraction (XRD), N₂-adsorption/desorption isotherm measurements, and H₂-temperature programmed reduction (TPR) measurements. Experimental results revealed that among the Me-doped Co₃O₄ catalysts, Ni/Co₃O₄ demonstrated the highest catalytic performance (X_CO = 93% with 47% H₂ yield at 280 °C). The higher activity of the Ni-doped Co₃O₄ catalyst was mainly due to its smaller crystallite size (8.6 nm) and strong interaction between Co and Ni, which lead to the higher reducibility of Co₃O₄ compared to the other metal-doped Co₃O₄. To further optimize the loading of Ni- over the mesoporous Co₃O₄, a series of Ni(x%)/Co₃O₄ catalysts were prepared by varying the Ni-loading in the range of 3 to 15 wt%. Among these catalysts, 5 wt% Ni- was found to be the optimum loading, whereas higher Ni-loaded samples (10 and 15 wt%) showed a decrease in catalytic performance and hydrogen yield during the WGS reaction.