Search

A series of ZSM-5/SBA-15 composite supported Co catalysts were prepared and evaluated for the Fischer–Tropsch synthesis (FTS) aimed to maximise the selectivity of C 5 –C 22 hydrocarbons in the product. The composite support was prepared by physically mixing ZSM-5 and SBA-15 of varying proportions and the finished catalysts had a constant Co loading of 15wt.%. The catalysts were tested for their performance in a high pressure fixed-bed reactor operating at T = 240 °C, P = 2.0 MPa, H 2 /CO = 2 and GHSV = 1000 h − 1 . The composite supported catalysts were shown to have much improved catalytic performance over the respective single material supported catalysts. The catalyst with 20wt.% ZSM-5 in the composite support gave the maximum CO conversion (90.6%), maximum selectivity of C 5 –C 22 hydrocarbons (70.0%) and minimum selectivity of light hydrocarbons (13.3% for CH 4 and 7.0% for C 2 –C 4 alkanes). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy with an energy dispersive X-ray spectrometer, temperature programmed desorption and temperature programmed reduction. It was revealed that the superior catalytic performance can be attributed to the large pore size and high dispersion of Co 3 O 4 , which afforded an optimum reducibility and acid site density. [ABSTRACT FROM AUTHOR]