Fischer-Tropsch synthesis. Influence of the crystal size of iron active species on the activity and selectivity

In order to analyze the influence of the crystal size of the active phase in the Fischer-Tropsch synthesis (FTS), two iron catalysts, supported on MCM-41 and SBA-15, were prepared by incipient wetness impregnation and tested in this reaction. The solids were characterized by atomic absorption spectroscopy, N2 adsorption, X-ray diffraction at low angles and Mössbauer spectroscopy. The activated catalysts showed the same iron species. However, the average crystal size of the active phase is about three times higher in SBA-15 than in MCM-41. Besides, both systems displayed a narrow size distribution. The catalyst with higher crystal size (Fe/SBA-15) presented higher conversion, higher chain growth and lower CH4 production. These results would indicate that the FTS is a “structure sensitive” reaction in a sizes range within, approximately, 3–10 nm.

Graphical abstractIn the present work the influence of the crystal size of the iron active phase in the Fischer-Tropsch synthesis (FTS) is evaluated. The catalyst with higher crystal size (Fe/SBA-15) presented higher conversion, higher chain growth and lower CH4 production. These results confirm that the FTS is a “structure sensitive” reaction in a sizes range within, approximately, 3–10 nm.Figure optionsDownload full-size imageDownload high-quality image (307 K)Download as PowerPoint slide