Effects of surface hydrophobization on the phase evolution behavior of iron-based catalyst during Fischer–Tropsch synthesis

Iron-based Fischer–Tropsch synthesis (FTS) catalyst is widely used for syngas conversion, but its iron carbide active phase is easily oxidized into Fe3O4 by the water produced during reaction, leading to the deterioration of catalytic performance. Here, we show an efficient strategy for protecting the iron carbide active phase of FTS catalyst by surface hydrophobization. The hydrophobic surface can reduce the water concentration in the core vicinity of catalyst during syngas conversion, and thus inhibit the oxidation of iron species by water, which enhances the C − C coupling ability of catalyst and promotes the formation of long-chain olefins. More significantly, it is unraveled that appropriate shell thickness plays a crucial role in stabilizing the iron carbide active phase without Fe3O4 formation and achieving good catalytic performance. The iron carbide active phase is easily oxidized by the water produced during Fischer-Tropsch synthesis, which leads to a deterioration in catalytic performance. Here, the authors present a strategy to protect iron carbide by applying surface hydrophobization.