High-performance VO_x on SrO-γAl₂O₃ catalyst for oxidative cracking of n-hexane to light olefins under anaerobic environment

Novel VO_x/SrO-γAl₂O₃ catalysts have been investigated in oxidative cracking of n-hexane to light olefins. The supports, with different SrO/γAl₂O₃ ratios, were synthesized by a surfactant-free method, while VO_x was incorporated on SrO-γAl₂O₃ by impregnation. NH₃-TPD showed that the acidity of the catalysts decreased with the increase of SrO. The incorporation of SrO also modified the reducibility (H₂-TPR) of the catalysts. VO_x appeared as amorphous polymeric species on the support, confirmed by XRD, Raman and FTIR analyses. The oxidative cracking of n-hexane was conducted by using a fluidized CREC Riser Simulator in absence of gas phase oxygen. Under the studied reaction conditions (525−600 °C; 10−25 s), the products contained mainly light olefins (ethylene, propylene and butenes), paraffins, and carbon oxides. Among the synthesized catalysts, VO_x/SrO-γAl₂O₃ 1:1 showed highest olefins selectivity (88%) at high n-hexane conversion (84%) because of its balanced acidity and moderate VO_x-support interactions.