Highly-Dispersed NiO Nanoparticles on SBA-15 for Oxidative Dehydrogenation of Propane to Propylene

A series of NiO/SBA-15 (w(NiO)=20%) catalysts were prepared by impregnating SBA-15 with an aqueous solution of nickel nitrate followed by calcining under three different atmospheres. The resulting materials were studied with regard to the oxidative dehydrogenation of propane (ODHP) to propylene. Compared to the catalysts calcined under either static or moving air, the NiO/SBA-15-NO catalyst calcined under flowing 1% NO/He (V-NO/V-He = 1:99) atmosphere demonstrated greater activity for this reaction at low temperature. Propylene yield of similar to 13% with propane conversion of similar to 29% was obtained at 350 degrees C and the propylene selectivity remained at about 45% even when the reaction temperature was raised to 450 degrees C. X-ray diffraction (XRD), transmission electron microscopy (TEM), H-2-temperature program reduction (H-2-TPR), and O-2-temperature program desorption (O-2-TPD) characterizations were used to investigate the intrinsic differences between these NiO/SBA-15 catalysts. It was found that NiO species in the catalyst calcined under 1% NO/He atmosphere were highly dispersed inside the mesopores of SBA-15. With the increasing of NiO dispersion on the support, the quantity of NiO species with a reduction temperature above 450 degrees C increased significantly. In addition, the density of O- species on the catalyst calcined under 1% NO/He was much higher than that in the case of the other two samples. These factors are responsible for the superior performance of the NiO/SBA-15-NO catalyst for the ODHP reaction over the temperature range 350 to 450 degrees C.