Production of butadiene and lower olefins via oxidative conversion of n-butane over Ni-Bi-O/zeolite catalysts

The on-purpose production of butadiene and light olefins via oxidative conversion of n-butane was investigated over nanocomposites of Ni-Bi-Si oxides comprising Bi₁₂SiO₂₀/Bi₂SiO₅ phase regulated with silica of Beta, USY and ZSM-5 zeolites. Different ratios of Bi₁₂SiO₂₀ and Bi₂SiO₅ phases were obtained depending on the zeolite species and its SiO₂/Al₂O₃ ratio. The Ni-Bi-Si oxides were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, etc. to examine the electronic state and oxygen mobility in specific Bi-Si oxides; Bi₂SiO₅ and Bi₁₂SiO₂₀. The active species-zeolites interaction controlled the reducibility of Ni-Bi-O system and acidity of the catalysts. Ni-Bi-O/ZSM-5(1500) catalyst exhibited high selectivity for the oxidative conversion of n-butane to ethylene and propylene (60.7 wt. %) at 16 % conversion. Similarly, the olefinic selectivity over NiO-Bi₁₂SiO₂₀-Bi₂SiO₅/ZSM-5(280) catalyst at 20 % conversion, was 87 % (ethylene and propylene = 28.3 %, C4 olefins = 58.6 % including BD = 20 %) at 500°C and feed ratio of O₂/n-butane = 2.0.