In situ transformation of Fisher-Tropsch products into high-octane gasoline-range hydrocarbons by using hybrid zeolite-based catalysts

Hybrid FeCoK-zeolite (1/1 wt/wt) catalysts have been prepared and evaluated for the in situ transformation of primary Fischer-Tropsch (FT) products into high-octane gasoline-range hydrocarbons. The selectivity to C5−C12 (gasoline) significantly increased in the presence of zeolite in detriment of heaviest (C13+) hydrocarbons. Different reaction paths prevailed depending on the topology and Brönsted acidity of the zeolite co-catalyst. Cracking of the C13+ products into mainly isoparaffins was favored over zeolites having larger pores and/or cavities and high density of strong Brönsted acid sites (MCM-22, delaminated ITQ-2), though they deactivated at a relatively fast rate. By contrast, aromatization of light olefins prevails over the medium pore ZSM-5 zeolite. The stability of the catalyst with TOS could be improved by incorporation of small amounts of a noble metal (1 wt% Pd) to the zeolite.