Selective Iron Catalysts for Direct Fischer–Tropsch Synthesis to Light Olefins
Zhenxin Liu, Gaopeng Jia, Chenxi Zhao, Yu Xing
Abstract
Ethylene, propylene, and butylene may be directly produced through selective CO hydrogenation over Fischer–Tropsch to light olefins (FTO) catalysts. It is known that Fe-based catalysts promoted by S/Na synergistic effect may reach a C2=–C4= hydrocarbon selectivity of 53% at 20 bar. Herein, we report a zeolite-free, potassium-promoted iron FTO catalyst modulated by high-temperature annealed composite oxides, 15%Fe/2%K2O/83%ZnAl8O13, exhibiting a C2=–C4= hydrocarbon selectivity of 64.4% at a total pressure of ca. 20 bar, which is one of the best practicable hydrocarbon selectivity values for Fe-based FTO catalysts so far. Simultaneously, its contents of ethylene in C2 (i.e., the C2 olefin fraction), propylene in C3 (i.e., the C3 olefin fraction), and butylene in C4 hydrocarbons (i.e., the C4 olefin fraction) achieve 88, 92, and 89%, respectively.