Effects of Structure and Particle Size of Iron, Cobalt and Ruthenium Catalysts on Fischer–Tropsch Synthesis

Abstract

This review emphasizes the importance of the catalytic conversion techniques in the production of clean liquid and hydrogen fuels (XTF) and chemicals (XTC) from the carbonaceous materials including coal, natural gas, biomass, organic wastes, biogas and CO2. Dependence of the performance of Fischer–Tropsch Synthesis (FTS), a key reaction of the XTF/XTC process, on catalyst structure (crystal and size) is comparatively examined and reviewed. The contribution illustrates the very complicated crystal structure effect, which indicates that not only the particle type, but also the particle shape, facets and orientation that have been evidenced recently, strongly influence the catalyst performance. In addition, the particle size effects over iron, cobalt and ruthenium catalysts were carefully compared and analyzed. For all Fe, Co and Ru catalysts, the metal turnover frequency (TOF) for CO hydrogenation increased with increasing metal particle size in the small size region i.e., less than the size threshold 7–8 nm, but was found to be independent of particle size for the catalysts with large particle sizes greater than the size threshold. There are some inconsistencies in the small particle size region for Fe and Ru catalysts, i.e., an opposite activity trend and an abnormal peak TOF value were observed on a Fe catalyst and a Ru catalyst (2 nm), respectively. Further study from the literature provides deeper insights into the catalyst behaviors. The intrinsic activity of Fe catalysts (10 nm) at 260–300 °C is estimated in the range of 0.046–0.20 s−1, while that of the Co and Ru catalysts (7–70 nm) at 220 °C are 0.1 s−1 and 0.4 s−1, respectively.

Production of Light Olefins via Fischer-Tropsch Process Using Iron-Based Catalysts: A Review

“…They reported that the iron carbide is the most crucial active phase for olefin production through FT reaction, and also the larger pore size of iron-based catalysts could result in a higher olefin production and decrease the readsorption and secondary reactions. According to the findings reported in the literature, Yahyazadeh et al [115] and Ma and Dalai [116] also reported that the support's properties could significantly affect the catalyst performance. The desirable interaction with metal and support needs to be considered during the selection of the support.…”

Fe Nanoparticle Size Control of the Fe-MOF-Derived Catalyst Using a Solvothermal Method: Effect on FTS Activity and Olefin Production

“…This is manifested by the different FTS performances of the two catalysts, as shown in the previous sections. According to the literature, iron particle size is one of the parameters that has a profound effect in nanocatalysis, especially on FTS performance, including X CO , , , hydrocarbon selectivity, and FTY. , As noticed from the TEM data of this work, the average iron particle size of Fe-MIL-88B-T/C (5.8 nm) is far smaller than that of Fe-MIL-88B-S/C (35.0 nm). In general, Fe-MIL-88B-T/C shows higher X CO percentages than Fe-MIL-88B-S/C.…”

“…Several studies proposed that the textural properties of the support and the pore size and particle size of the active metal considerably impact catalytic activity and olefin selectivity. , However, the pore size effect appears to be overlapping with the particle size effect. , The effect of metal particle size on FTS performance has been generally studied on Fe, Co, and Ru catalysts. , …”

Special Issue Editorial: Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals

“…Two review contributions are included in this special issue as well. One review by Professors Ma and Dalai highlighted the effects of structure and particle size of Fe, Co, and Ru catalysts on Fischer-Tropsch Synthesis (FTS) [14,15]. The complicated crystal structure effect including phase type, for example, various iron carbides (Fe 7 C 3 , χ-Fe 5 C 2 , θ-Fe 3 C, ε-Fe 2 C), fcc and hcp cobalt and fcc and hcp ruthenium, phase shape, and crystal facets, were discussed and reviewed [14].…”

“…One review by Professors Ma and Dalai highlighted the effects of structure and particle size of Fe, Co, and Ru catalysts on Fischer-Tropsch Synthesis (FTS) [14,15]. The complicated crystal structure effect including phase type, for example, various iron carbides (Fe 7 C 3 , χ-Fe 5 C 2 , θ-Fe 3 C, ε-Fe 2 C), fcc and hcp cobalt and fcc and hcp ruthenium, phase shape, and crystal facets, were discussed and reviewed [14]. Two particle size regions spitted at 7-8 nm were pointed out for all metals, and the useful intrinsic activity values of all metals were estimated, i.e., TOF 0.046-0.20 s −1 for Fe catalysts (10 nm) at 260-300 • C, 0.1 s −1 and 0.4 s −1 (the highest) for Co and Ru catalysts (7-70 nm) at 220 • C, respectively.…”