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Iron/nanospring (Fe/NS) catalysts with different metal promoters (Co, Mo, Cu, and Ru) were synthesized via the co-impregnation method and employed to investigate effects of these metals on the physico-chemical properties and catalytic behavior of Fe/NS catalyst during the Fischer-Tropsch synthesis (FTS). The prepared catalysts were characterized before the FTS reaction by various techniques, such as BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), temperature programmed reduction (H 2 -TPR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The FTS performance of the prompted catalysts was examined in a quartz fixed-bed microreactor (H 2 /CO of 2:1, 230 °C and atmospheric pressure) and the products trapped and analyzed by gas chromatography (GC) and GC-mass spectrometry (GC–MS) to determine CO conversion and reaction selectivity. The characterization results obtained indicated that the promotion of Fe/NS catalyst with Co, Mo, Cu and Ru oxides enhanced the catalytic activity of Fe/NS catalyst. The catalytic performance over Ru-Fe/NS, Co-Fe/NS, Mo-Fe/NS and Cu-Fe/NS catalysts at the same conditions showed that CO conversion was 93.3%, 43.6%, 82.4% and 56.3%, respectively. The C 6 -C 16 liquid hydrocarbon selectivity was 41.1%, 30.1%, 25.4% and 33.8%, respectively. The addition of promoters led to an increase in the selectivity towards olefins instead of aromatics over the non-promoted Fe/NS catalyst. Finally, it was found that the Ru, Co, MO and Cu promoters proved to have a significant effect on selectivity towards desired products namely paraffins and olefins. [ABSTRACT FROM AUTHOR]

A nanostructured iron (Fe) catalyst for Fischer-Tropsch synthesis (FTS) was prepared and evaluated using a silica nanospring (NS) support. FTS offers an approach of producing biofuels from synthesis gas (syngas) produced via biomass gasification. The Fe/NS catalysts were prepared using three different methods: (i) incipient wetness impregnation, (ii) precipitation and (iii) modified sol-gel, in order to obtain different sizes of deposited Fe nanoparticles on the NS support and investigate the influence of particle size on FTS. The Fe decorated catalysts were calcined and then activated with either H 2 , CO or H 2 + CO mixture. The prepared Fe/NS catalysts were characterized before the FT reaction by BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. The decoration of Fe nanoparticles of different sizes onto NS using the various methods ranged from 1.7 to 10 nm. The FTS performance was also evaluated in a quartz fixed-bed microreactor (H 2 /CO of 2:1, 270 °C) and the products trapped and analyzed by GC-TCD and GC–MS to determine CO conversion and reaction selectivity. These results show that the highest CO conversion (76.6%) and a wide distribution of light hydrocarbon (C 6 to C 14 ) were obtained for Fe/NS catalyst prepared by impregnation and activated with CO after 12 h of the FT reaction. [ABSTRACT FROM AUTHOR]