Hydrophobic interfaces regulate iron carbide phases and catalytic performance of FeZnOx nanoparticles for Fischer-Tropsch to olefins.

Fischer-Tropsch to olefins (FTO) with controllable iron carbide phase and high carbon utilization efficiency for Fe-based nanocatalyst attracts great interest but remains challenge. Herein, we report that the metastable Fe 7 C 3 phase can be effectively tailored by altering shell thickness of hydrophobic SiO 2 over a core-shell nanostructured FeZn@SiO 2 -c nanocatalyst. χ-Fe 5 C 2 was the dominated iron carbide phase for FeZnO x and FeZn@SiO 2 nanocatalysts, while numerous Fe 7 C 3 phases existed for hydrophobic FeZn@SiO 2 -c nanospheres. Compared with FeZnO x , the CO 2 selectivity of FeZn@ 4.1-SiO 2 -c decreased by > 70%, while 1.7-fold higher olefins selectivity was simultaneously obtained during syngas conversion process. The hydrophobic interface greatly suppressed the water-gas-shift reaction by promoting the quick diffusion of water, and the as-formed H 2 -lean and CO-rich local chemical environment benefits the formation of Fe 7 C 3 and olefins products. This work provides a promising strategy to design phase-stable Fe 7 C 3 with improvement of carbon efficiency for Fe-based nanocatalysts. [Display omitted] • Hydrophobic interfaces could regulate iron carbide phases. • Hydrophobic confined environment benefits the design of phase-stable Fe 7 C 3 carbide. • Fe 7 C 3 is a favorable active phase for Fischer-Tropsch to olefins (FTO). • Wettability environment affects WGS reaction activity and FTO performance. • Suppressed CO 2 selectivity, enhanced activity and olefins selectivity was obtained. [ABSTRACT FROM AUTHOR]