FeMn@HZSM-5 capsule catalyst for light olefins direct synthesis via Fischer-Tropsch synthesis: Studies on depressing the CO2 formation

For Fe-based Fischer-Tmpsch synthesis catalyst, how to decrease CO2 formation is a big challenge. In this work, a capsule catalyst (FeMn@HZSM-5) with FeMn as core and HZSM-5 as shell was prepared and used for Fischer-Tropsch to olefins (FTO) reaction, compared with bare FeMn catalyst and several hybrid catalysts by physically mixing FeMn and HZSM-5 in different ways. Among these catalysts, the FeMn@HZSM-5 capsule catalyst showed the best catalytic performance with the highest light olefins selectivity and the lowest CO2 selectivity. Compared with FeMn catalyst, the CO2 selectivity of FeMn@HZSM-5 catalyst decreased more than 10%. However, the CO2 selectivity of other physically mixing catalysts was similar to that of bare FeMn catalyst, indicating that randomly adding HZSM-5 had no effect on depressing the CO2 formation. Benefiting from the HZSM-5 shell, the FeMn@HZSM-5 capsule catalyst could effectively affect the diffusion of H2O and thus suppress the water-gas shift reaction in FTO reaction.

Automated summary

The capsule catalyst FeMn@HZSM-5 was shown to effectively reduce CO2 formation and increase olefins selectivity in Fischer-Tropsch to olefins (FTO) reaction, outperforming other physically mixing catalysts. The HZSM-5 shell played a key role in affecting H2O diffusion and suppressing the water-gas shift reaction.