Tuning the properties of NiO supported on silicon-aluminum oxides: Influence of the silica amount in the ODH of ethane

Nickel-based catalysts (40 wt% Ni) with commercial silicon-aluminum oxides as supports were prepared. The variation of the silica amount (10%, 20% and 40%) was studied. These catalytic formulations were characterized by N2 adsorption, SEM/EDX, HR-TEM, XRD, LRS and XPS, and tested in the oxidative dehydrogenation of ethane (ODHE) to produce ethylene. Besides, they were compared with a nickel-based silica-supported catalyst (NiO/ SiO2). The effect of the proportion of silica in the supports on the generated Ni species, and consequently on the respective catalytic performances, was investigated. The results showed that, despite of the same NiO loading in all catalysts, different NiO-support interactions and surface amounts of non-selective oxygen species were obtained. These features had an impact on the catalytic behavior of each formulation. Remarkably, while ethylene selectivity was high and almost the same, ethane conversion increased with the silica amount in the supports. On the other hand, as expected, pure silica as a support resulted in high conversion but markedly low selectivity, favoring the total ethane oxidation to carbon dioxide. This work demonstrates that it is possible to increment the alkane conversion without sacrificing the alkene selectivity by tuning the active species properties through the increase of the amount of silica in the supports.