In:
Catalysis Science & Technology, Royal Society of Chemistry (RSC), Vol. 12, No. 19 ( 2022), p. 5814-5828
Abstract:
We demonstrated two design methods for obtaining Fe catalysts to improve the olefin selectivity in Fischer–Tropsch synthesis (FTS) reactions through the use of a SiO 2 support. Fe/SiO 2 catalysts, synthesized through classical impregnation, and Fe–SiO 2 catalysts, synthesized through impregnation followed by calcination at 1700 °C, with Fe loadings of 1, 5, and 10 wt% were obtained. The Fe–SiO 2 catalysts achieved C2–C4 olefins in C2–C4 hydrocarbons, O/(O + P), of 62.5–73.0%, whereas the O/(O + P) of the Fe/SiO 2 catalysts decreased significantly with high Fe loadings. Using various characterization techniques, the main carbide species was identified to be Fe 5 C 2 , and based on the crystal size and composition of the Fe species, it was concluded that the interactions of Fe–SiO 2 catalysts with SiO 2 are of moderate strength. The iron time yield of C2–C4 olefins (FTY C2–C4 olefins ) as a function of the Fe 5 C 2 composition was higher for the Fe–SiO 2 catalysts than for the Fe/SiO 2 catalysts with corresponding Fe loadings; the highest value obtained for 1 wt% Fe–SiO 2 was a factor of 3.5 higher than that of 1 wt% Fe/SiO 2 . The reaction results showed that the C2–C4 olefins can be selectively produced using the Fe–SiO 2 catalyst even with a high Fe content. A density functional theory (DFT) study was performed to investigate the effect of SiO 2 promotion on Fe carbides, and it was concluded that SiO 2 promotion resulted in high selectivity for olefins, CH 4 , and CO 2 . To suppress CH 4 or CO 2 formation and boost CO conversion, Na-added catalysts with various Na ratios were tested, and successfully reduced CH 4 selectivity and enhanced CO conversion.
Type of Medium:
Online Resource
ISSN:
2044-4753
,
2044-4761
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2595090-3
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