Application fischer-tropsch synthesis: a review

Abstract

This work was to evaluate the catalytic properties Ru/Cobalt/SBA-15 catalyst for Fischer-Tropsch synthesis (FTS). The molecular sieve SBA-15 synthesized by hydrothermal method with rice husk ashes (RHA) and with tetraethyl orthosilicate (TEOS). The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalysts were carried out to evaluate the catalysts activities and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO : H2 molar ratio of 1 : 2. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present under the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. By RTP results was found the ranges of temperature reduction typical of iron oxides phases. Fischer-Tropsch synthesis activity and C5+hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. The most interesting fact to be pointed out is that the use of this catalytic system for the catalyst prepared with alternative source of silica and cheap (rice hull ash) showed high selectivity in liquid products, that is, in hydrocarbons with C5+ (88.2% w/w), higher than the catalyst prepared with conventional silica source.