Effect of support in Ni-Bi-O/support catalyst on oxidative dehydrogenation of n-butane to butadiene

NiO-Bi₂O₃/different support catalysts, 20 wt% Ni and 30 wt% Bi as metal weight to support weight (hereafter 20wt%Ni-30wt%Bi-O/support) have been studied for oxidative dehydrogenation of n-butane to butadiene. Al₂O₃, SiO₂, ZrO₂ and none (: without support) were served as gel and sol type supports. As the results, activity and selectivity of oxidative dehydrogenation of n-butane to butadiene over the Ni-Bi-O/support catalyst strongly depended on the supports. The order of the butadiene selectivity as gel-type support was Al₂O₃ > SiO₂ > ZrO₂ ≫ none, while SiO₂ showed the highest butadiene selectivity from 1-butene feedstock. The gel-type support effect as a hierarchical nano-particle cohabitation was also studied by using equilibrium adsorption method for the Ni-Bi-O impregnation. In the sol-type support case, the order is SiO₂ > Al₂O₃ > ZrO₂, where the SiO₂ sol shows not only superior to gel-type but also the best performance (n-butane conversion: 35.6%, selectivity: dehydrogenation 78.3%, butadiene 41.6%) among support types and species. The sol-type SiO₂ hold balanced acid and base sites cooperating to improve butadiene selectivity, with oxygenate suppressed by accelerating redox system with non-hierarchical nano-particle cohabitation of NiO, Bi₆O₇ and support SiO₂.