Support effects on the catalytic behavior of NiO/Al2O3 for oxidative dehydrogenation of ethane to ethylene

Six representative Al₂O₃ supports with different specific surface areas and pore volumes were used to prepare NiO/Al₂O₃ catalysts with two NiO loadings. Oxidative dehydrogenation of ethane (ODE) to ethylene was investigated over these catalysts. The yield of ethylene was found to be approximately proportional to the pore volume/surface area ratio of the support used for that catalyst. X-ray diffraction analysis (XRD), TEM and H₂-TPR were employed to characterize their structure differences. It was found that the physical properties of the Al₂O₃ supports were crucial to the dispersion of NiO. More large crystal NiO was found on the Al₂O₃ supports with lower pore volume, while more highly dispersed NiO was formed on the Al₂O₃ supports with higher pore volume. An interpretation based on the pore volume of the supports and the physical properties of salt precursors was proposed.