The impact of synthesis method of CNT supported CeZrO₂ and Ni-CeZrO₂ on catalytic activity in WGS reaction

Carbon nanotube (CNT) supported catalysts containing ceria-zirconia mixed oxide (CeZrO₂) and nickel were synthesized and tested in water gas shift (WGS) reaction. Physicochemical characterization including N₂ adsorption, X-ray diffraction (XRD), scanning and transmission microscopy (SEM/TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and temperature programmed reduction with H₂ (H₂-TPR), as well as catalytic tests of WGS reaction showed that the synthesis method had significant impact on composition, morphology, structural properties and catalytic performance of obtained hybrid materials. The catalysts obtained by co-precipitation of metal oxides (NiO and/or CeZrO₂) on CNT walls demonstrated better dispersion of active phase and smaller particle size than catalyst obtained by depositing of powder CeZrO₂ or Ni-CeZrO₂. Moreover, the catalyst obtained by co-precipitation revealed better performance in WGS reaction; however, some CH₄ formation was noticed over Ni-CeZrO₂/CNT system. The role of CeZrO₂ in catalysts performance in WGS as well as the importance of good metal-oxide contact were confirmed.