Tandem catalysis of zeolite and perovskite for light olefins production in dehydrogenation cracking of naphtha

Abstract

Considerable energy consumption and high CO₂ emissions of steam cracking have driven the exploration of alternative methods for light olefins production from naphtha. In this context, we propose a novel dehydrogenation cracking approach as an alternative route for naphtha conversion. By employing a perovskite-based redox catalyst, CaMnO₃@Na₂WO₄, in combination with zeolite-based catalyst, model compound n-octane undergoes dehydrogenation to form octene, significantly reducing the activation energy required for C–C bond cleavage. This approach enhances the yield and selectivity of light olefins. When mixing ratio of dehydrogenation catalyst in tandem catalysis is 5%, the conversion reaches 90.07%, and the total light olefins yield is 47.90%. The influence of factors such as reaction temperature, coupling mode and mixing ratio were also demonstrated. Comparing to standalone zeolites, 15% higher olefin yields were obtained with tandem mixed catalysts, demonstrating the excellent dehydrogenation cracking ability. The optimized dehydrogenation temperature at 450 °C, could provide an optimal reaction environment for this elementary dehydrogenation reaction and decrease the energy consumption. Synergetic effect of zeolite-based catalyst with different mixing ratio of CaMnO₃@Na₂WO₄ also leads to tunable P/E ratio. Theoretical calculations of reaction routes provided valuable insights for the further development and optimization of naphtha conversion processes.