Effect of support and promoters in Fischer-Tropsch synthesis using supported iron catalysts

L. CANO; A. A. GARCÍA BLANCO; G. LENER; D. BARRERA; K. SAPAG

Cancun

Congreso; XXVI International Materials Research Congress; 2015

The effect of support and activity promoters on the catalytic properties of Fe supported in the Fischer-Tropsch synthesis at high pressure, was studiedby combining DFT calculations and experimental results. Precursors of supported Fe on SiO2 and SBA -15 were synthesized,which were doped with Cu to increase the activity and stability and with K to increase selectivity towards olefins. The precursors were activated in pure H2 stream and catalytically tested with a mixture of H2: CO = 2:1, a reaction temperature of 543 K and 10 bar of pressure. The samples were characterized by atomic absorption, N2 adsorption, X-ray diffraction, TEM spectroscopy and temperature programed reduction .Also, we used the Density Functional Theory to study the changes of the electronic structure when the Fe, K and Cu atoms are adsorbed on the SBA-15 surface. The incorporation of different ions in the precursors do not alter the structural and textural properties of the mesoporous support. In the Fischer Tropsch synthesis, all the catalysts supported on SBA-15 presented a low selectivity towards methane and a promising hydrocarbon production in the range of gasoline, showing positive effect of the support for iron catalysts for the FTS reaction. The activity order obtained in the FTS was: Fe/K-SBA-15> Fe/Cu-SBA-15 ≈ Fe-SBA-15 > Fe-SiO2,which is the same order for the selectivity towards olefins. The differencesobserved among the catalysts confirms that the presence of the K cations on the SBA-15 surface increases the activity and selectivity towards olefins; an effect that can be attributed to the electrostatic effect generated by the alkaline ions.