Methane decomposition into COx-free hydrogen and carbon nanomaterials over ZrO2–M (M = MgO, Al2O3, SiO2, La2O3 or CeO2) binary oxides supported cobalt catalysts

Abstract

Hydrogen production via methane decomposition has attracted great attention as a source of clean energy. In this work, the catalytic decomposition of undiluted methane into COx-free hydrogen and carbon nanomaterial over ZrO2–M (M = MgO, Al2O3, SiO2, La2O3 and CeO2) binary oxides supported Co catalysts was studied. The fresh and spent catalysts were characterized by XRD, H2-TPR, N2 adsorption–desorption, TEM and Raman spectroscopy. The results revealed that the incorporation of secondary oxide to ZrO2 support played a vital role in the activity and stability of cobalt metal. The activity results illustrated that Co/Zr–Mg exhibited better activity in terms of hydrogen yield compared with the other Zr–M supported catalysts. This is ascribed to the moderate cobalt oxide-support interaction and forming CoMgOx species which enhance the Co3O4 dispersion and prevent its aggregation on the catalyst surface. On the other hand, the Co/Zr–Si catalyst showed the lowest activity due to the agglomeration of Co3O4 on the surface of the SiO2 support. High-resolution TEM images illustrated that almost the deposited carbon on the surface of spent catalysts was in the form of multi-walled carbon nanotubes.