Pore structure effect of support in Ni-Bi-O/mesoporous silica catalyst on oxidative dehydrogenation of n-butane to butadiene

Ni-Bi-O/structured mesoporous (MCM-41, SBA-15, and silica foam) silica catalyst with 20 wt% Ni and 30 wt% Bi has been studied in oxidative dehydrogenation of n-butane to butadiene. Mesoporous SBA-15 showed a clear superiority in activity and selectivity as compared to MCM-41, silica foam and conventional silica. The order of the butadiene yield was SBA-15 > Silica foam > MCM-41 > conventional silica. SBA-15 catalyst exhibits the best performance (butadiene selectivity: 47.5% at n-butane conversion: 28.9%) due to the presence of Bi ₂ O _3-a phase (a = 0.2-0.4) as well as the strong base with weak/moderate acid sites, as evident from XRD and TPD analysis, respectively. The formation of Bi ₂ O _3-a (a = 0.2-0.4) phase is related to the template effect of structurally ordered silica.