EFFECT OF THE ACTIVATION ATMOSPHERE IN THE ACTIVITY OF FE CATALYSTS SUPPORTED ON SBA-15 IN THE FISCHER-TROPSCH SYNTHESIS.

MARÍA V. CAGNOLI, LEONARDO A. CANO, JOSÉ F. BENGOA, ANA M. ÁLVAREZ AND SERGIO G. MARCHETTI.

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Netherlands; Año: 2009 vol. Env.

0926-860X

An iron catalyst supported on a mesoporous solid, called SBA-15, was prepared by incipient wetness impregnation and activated following two different methodologies, in pure H2 stream and in synthesis gas (H2:CO=2:1) stream, in order to be used in the Fischer-Tropsch synthesis. The solids were characterized by atomic absorption spectroscopy, N2 adsorption, X-ray diffraction at low angles, Mössbauer spectroscopy and temperature programmed hydrogenation. Different iron species were obtained after the different activation treatments: Fe2+ diffused into the SBA-15 walls, Fe3O4 and Feº for the catalyst activated in pure H2 stream and Fe2+, Fe3O4 and χ-Fe5C2 carbide for the catalyst activated in synthesis gas. The initial “bulk” structural differences would disappear while the catalysts are “working”. However, the catalytic tests showed a higher total hydrocarbon production, a higher CO conversion and a higher selectivity towards light olefins when the activation was carried out in pure H2 stream. These results would indicate that the initial differences in the structure of the active sites are maintained during the reaction.