Fischer–Tropsch synthesis: Iron catalysts supported on N-doped carbon spheres prepared by chemical vapor deposition and hydrothermal approaches

Xiong, Haifeng; Moyo, Mahluli; Motchelaho, Myriam A.M.; Tetana, Zikhona N.; Dube, Sibongile Mary-Anne; Jewell, Linda L.; Coville, Neil J.

doi:10.1016/j.jcat.2013.11.007

Cited by 107 publications

(71 citation statements)

References 40 publications

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“…For example, in studies on Fe/CNT for use as FTS catalysts, N-functionalization is often used to enhance the anchoring of Fe particles in the CNTs, thus increasing their activity and stability [46][47] . Furthermore, the increased addition of N groups to the support often decreases the CH 4 selectivity in FTS over these N-doped carbons 48 . Therefore, EDX mapping of large clusters of catalysts was performed on the samples that contained impurities in the XPS spectra (Table 5, Figure S10 and S11).…”

Section: Catalytic Testingmentioning

confidence: 99%

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

et al. 2017

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The structure and elementary composition of various commercial Fe-based MOFs used as precursors for Fischer–Tropsch synthesis (FTS) catalysts have a large influence on the high-temperature FTS activity and selectivity of the resulting Fe on carbon composites. The selected Fe-MOF topologies (MIL-68, MIL-88A, MIL-100, MIL-101, MIL-127, and Fe-BTC) differ from each other in terms of porosity, surface area, Fe and heteroatom content, crystal density and thermal stability. They are re-engineered towards FTS catalysts by means of simple pyrolysis at 500 °C under a N2 atmosphere and afterwards characterized in terms of porosity, crystallite phase, bulk and surface Fe content, Fe nanoparticle size and oxidation state. We discovered that the Fe loading (36–46 wt%) and nanoparticle size (3.6–6.8 nm) of the obtained catalysts are directly related to the elementary composition and porosity of the initial MOFs. Furthermore, the carbonization leads to similar surface areas for the C matrix (SBET between 570 and 670 m2 g−1), whereas the pore width distribution is completely different for the various MOFs. The high catalytic performance (FTY in the range of 1.9–4.6 × 10−4 molCO gFe−1 s−1) of the resulting materials could be correlated to the Fe particle size and corresponding surface area, and only minor deactivation was found for the N-containing catalysts. Elemental analysis of the catalysts containing deliberately added promoters and inherent impurities from the commercial MOFs revealed the subtle interplay between Fe particle size and complex catalyst composition in order to obtain high activity and stability next to a low CH4 selectivity.

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Section: Catalytic Testingmentioning

confidence: 99%

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

et al. 2017

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“…The N 1s spectrum is composed of four peaks at 398.7 AE 0.3, 400.3 AE 0.2, 401.4 AE 0.3, and 403 AE 0.3 eV, which are assigned to pyridinic nitrogen (N-6), pyrrolic nitrogen (N-5), quaternary nitrogen (N-Q), and pyridine-N-oxide (N-X), respectively. [37][38][39][40][41][42] The percent contributions of surface nitrogen species are summarized in Table 4, and the dominant nitrogen species on the surface of nitrogen-doped activated carbons are pyridinic nitrogens. Nitric acid oxidation leads to higher relative contents of pyridine-N-oxide and less pyrrolic nitrogen.…”

Section: -35mentioning

confidence: 99%

High-performance removal of methyl mercaptan by nitrogen-rich coconut shell activated carbon

Liu

et al. 2017

RSC Adv.

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A series of nitrogen-doped coconut shell activated carbon catalysts were prepared by urea or melamine impregnation followed by heat treatment and used for the removal of methyl mercaptan (CH 3 SH). The physical and chemical properties of the nitrogen-doped coconut shell activated carbons were evaluated by nitrogen adsorption/desorption, scanning electron microscopy, X-ray photoelectron spectroscopy, elemental analysis, Boehm titration, and thermal analysis. The results show that CH 3 SH capacity depends on the nitrogen content. Further research indicates that pyridinic nitrogen and quaternary nitrogen are the active sites. Due to the metal-free property of the nitrogen-rich coconut shell activated carbon, the regeneration process can be easily performed and dimethyl disulfide (CH 3 SSCH 3 ) can be recovered as the main product. Our study indicates that there is a promising prospect for nitrogen-rich coconut shell activated carbon for CH 3 SH removal because of its high capacity, mild conditions, and easy regeneration.

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“…The same appliest ot he study of carbon spheres (CSs) made by CVD. [25][26][27] The hydrothermalm ethod is an alternative process to prepares pherical carbon materials as it uses cheap carbon sources, mild reaction conditions andi st otally "green" as it involves no organic solvents, catalystso rs urfactants. [28,29] The most important advantage of CSs synthesised by the hydrothermal route is that they are hydrophilic and have useful surface functionalities, which facilitatesc hemical-surfacem odifications, at ask that is challenging if CVD-synthesised carbon materials are used.…”

Section: Introductionmentioning

confidence: 99%

“…The reported CS supports were either synthesised by CVD [25] or the hydrothermal methodb ut without annealing. [26] Consequently,t he reported support materials had low BET surfacea reas( < 5m 2 g À1 ). Thus, generally low FT activities were reported on these support materials even after functionalizing by KMnO 4 or nitrogen doping.…”

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confidence: 97%

Carbon Spheres Prepared by Hydrothermal Synthesis—A Support for Bimetallic Iron Cobalt Fischer–Tropsch Catalysts

et al. 2015

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Carbon spheres (CSs) synthesised by the hydrothermal approach were explored as a model support material for a bimetallic Fe–Co Fischer–Tropsch (FT) catalyst. The CSs were characterised by N2 adsorption–desorption, thermogravimetric analysis, FTIR spectroscopy and powder XRD. If annealed at 900 °C for 4 h, the CSs exhibited an improved surface area, thermal stability and crystallinity. A series of Fe–Co bimetallic FT catalysts supported on the annealed CSs were prepared by co‐precipitation. A variety of Fe‐to‐Co ratios were used with the total metal loadings maintained at 10 %. Catalyst reducibility studies were performed by H2 temperature‐programmed reduction and in situ powder XRD. Catalysts with a Fe/Co ratio of 5:5 (w/w) showed Co–Fe alloy formation upon reduction at >450 °C. Interestingly, the presence of this alloy did not correlate with high C5+ selectivities during FT synthesis; rather the Co‐rich/Fe‐poor catalyst gave the best selectivity. The CSs allowed the metal–metal interactions in the bimetallic systems to be monitored because of the weak interaction of the metals with the support.

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Fischer–Tropsch synthesis: Iron catalysts supported on N-doped carbon spheres prepared by chemical vapor deposition and hydrothermal approaches

Cited by 107 publications

References 40 publications

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

High-performance removal of methyl mercaptan by nitrogen-rich coconut shell activated carbon

Carbon Spheres Prepared by Hydrothermal Synthesis—A Support for Bimetallic Iron Cobalt Fischer–Tropsch Catalysts

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