Catalytic Oxidative Cracking of Light Alkanes to Alkenes

A review on the catalytic oxidative cracking of light alkanes to alkenes is presented as an alternative route to steam cracking for production of alkenes. Catalytic oxidative cracking is a combination of heterogeneous and homogeneous reactions; the reaction is initiated on the catalyst surface followed by thermal gas phase cracking. The review focuses on the catalytic generation of alkyl radicals at moderate temperatures (550-650 degrees C) using the Li/MgO system. Comparison with other catalyst systems such as Li/Y2O3, Au/La2O3, Au-SCZ, BiOCl, B2O3/Al2O3, Co-N/Al2O3 and Pt/Al2O3 monoliths is included. Gold supported on sulfated ceria-zirconia catalyst (Au-SCZ) is concluded to be a promising catalyst for further study. In addition to catalytic initiation of radicals, the review discusses alkyl generation using non-equilibrium plasma. Plasma-catalysis in oxidative cracking induces synergy effects and introduces significant improvement in yields of alkenes; however, further understanding of plasma chemistry needs to be elaborated. Minimizing CO2 production and maximizing yields of valuable C-2-C-4 alkenes remains the bottleneck for the commercialization of oxidative cracking process. Future research should focus on reactor design and on developing optimized reactor-catalyst systems.