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

Abstract

Novel VOx/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 VOx 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. VOx 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; 10−25s), the products contained mainly light olefins (ethylene, propylene and butenes), paraffins, and carbon oxides. Among the synthesized catalysts, VOx/SrO-γAl2O3 1:1 showed highest olefins selectivity (88%) at high n-hexane conversion (84%) because of its balanced acidity and moderate VOx-support interactions.