Journal articles: 'Iron catalysi'

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Dadashi-Silab, Sajjad, and Krzysztof Matyjaszewski. "Iron Catalysts in Atom Transfer Radical Polymerization." Molecules 25, no. 7 (April 3, 2020): 1648. http://dx.doi.org/10.3390/molecules25071648.

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Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-based monomers by iron catalysts still remains a challenge. In this paper, we review the fundamentals and recent advances of iron-catalyzed ATRP focusing on development of ligands, catalyst design, and techniques used for iron catalysis in ATRP.

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Hsueh, C. L., Y. H. Huang, C. C. Wang, and C. Y. Chen. "Photooxidation of azo dye Reactive Black 5 using a novel supported iron oxide: heterogeneous and homogeneous approach." Water Science and Technology 53, no. 6 (March 1, 2006): 195–201. http://dx.doi.org/10.2166/wst.2006.197.

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Photooxidation of azo dye Reactive Black 5 (RB5) by H2O2 was performed with a novel supported iron oxide in a batch reactor in the range of pH 2.5–6.0. The iron oxide was prepared through a fluidized-bed reactor (FBR) and much cheaper than the Nafion-based catalysts. Experimental results indicate that the iron oxide can significantly accelerate the degradation of RB5 under the irradiation of UVA light (λ=365 nm). An advantage of the catalyst is its long-term stability, which was confirmed through using the catalyst for multiple runs in the degradation of RB5. In addition, this study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in the batch reactor. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of RB5 during pH 4.5-6.0, the homogeneous catalysis is of increasing importance below pH 4.0 because of the Fe ions leaching from the catalyst to solution.

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Xu, Jun Qiang, Fang Guo, Shu Shu Zou, and Xue Jun Quan. "Optimization of the Catalytic Wet Peroxide Oxidation of Phenol over the Fe/NH₄Y Catalyst." Materials Science Forum 694 (July 2011): 640–44. http://dx.doi.org/10.4028/www.scientific.net/msf.694.640.

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The heterogeneous NH4Y zeolite-supported iron catalysts were prepared by incipient wetness impregnation. The catalysis oxidation degradation of phenol was carried over the heterogeneous catalyst in the peroxide catalytic oxidation process. Compared with the homogeneous Fenton process, the Fe/ NH4Y-acid catalyst can effectively degrade contaminants with high catalytic activity and easy catalyst separation from the solution. The phenol removal efficiency could reach 96% in the optimum experimental conditions. These process conditions were as follows: iron content is 5%, reaction time was 60 min, reaction temperature was 70 oC, the catalyst dosage was 1g/L, the H2O2 concentration was 1.65g/L.

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Guerrero Fajardo, Carlos Alberto, Yvonne N’Guyen, Claire Courson, and Anne Cécile Roger. "Fe/SiO2 catalysts for the selective oxidation of methane to formaldehyde." Ingeniería e Investigación 26, no. 2 (May 1, 2006): 37–44. http://dx.doi.org/10.15446/ing.investig.v26n2.14735.

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Selective oxidation of methane to formaldehyde was analysed with iron catalysts supported on silica prepared by the sol-gel method, leading to obtaining a large support surface area facilitating high dispersion of iron on silica’s amorphous surface. Seven catalysts were prepared; one of them corresponded to the silica support and another five having an iron load 0.1-0.5% in weight. Catalyst 7 (0.5% Fe in weight) was prepared with neutral pH control and had the most homogeneous characteristics since it did not present isolated iron species, corroborated by SEM and TEM analysis. The highest BET areas were 1,757 and 993 m2.g-1 for 0.5% Fe catalysts, having an average 36% microporosity and 43% mesoporosity. X-ray diffraction confirmed the catalyst’s amorphous structure. Catalytic activity was carried out with catalyser 7 at atmospheric pressure in a quartz reactor using a CH4/O2/N2=7.5/1/4 reaction mixture at 400-750°C temperature range. Reaction products were analysed by gas chromatography with TCD. The heterogeneous catalysts displayed greater methane conversion (but with methanol selectivity) whereas homogenous catalyst 7 gave better results regarding formaldehyde. The highest conversion percentage (8.60% mol) for catalyser 7 was presented at 650°C. Formaldehyde selectivity was 50% mol in the 600-650°C range and maximum yield (0.31g HCHO/Kg catalyst) was found in this range; it was thus considered that 650°C for the reaction was thereby the best operating temperature.

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van Slagmaat, Christian A. M. R., Khi Chhay Chou, Lukas Morick, Darya Hadavi, Burgert Blom, and Stefaan M. A. De Wildeman. "Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design." Catalysts 9, no. 10 (September 22, 2019): 790. http://dx.doi.org/10.3390/catal9100790.

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Asymmetric catalysis is an essential tool in modern chemistry, but increasing environmental concerns demand the development of new catalysts based on cheap, abundant, and less toxic iron. As a result, Knölker-type catalysts have emerged as a promising class of iron catalysts for various chemical transformations, notably the hydrogenation of carbonyls and imines, while asymmetric versions are still under exploration to achieve optimal enantio-selectivities. In this work, we report a novel asymmetric design of a Knölker-type catalyst, in which the C2-rotational symmetric cyclopentadienone ligand possesses chiral substituents on the 2- and 5-positions near the active site. Four examples of the highly modular catalyst design were synthesized via standard organic procedures, and their structures were confirmed with NMR, IR, MS, and polarimetry analysis. Density functional theory (DFT) calculations were conducted to elucidate the spatial conformation of the catalysts, and therewith to rationalize the influence of structural alterations. Transfer- and H2-mediated hydrogenations were successfully established, leading to appreciable enantiomeric excesses (ee) values up to 70%. Amongst all reported Knölker-type catalysts, our catalyst design achieves one of the highest ee values for hydrogenation of acetophenone and related compounds.

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Guo, Fang, Jun Qiang Xu, and Jun Li. "Kinetics Studies for Catalytic Oxidation of Methyl Orange over the Heterogeneous Fe/Beta Catalysts." Advanced Materials Research 807-809 (September 2013): 361–64. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.361.

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The Fe/Beta catalysts were prepared by conventional incipient wetness impregnation. The catalysis oxidation degradation of methyl orange was carried out in catalyst and H2O2 process. The results indicated that the catalyst and hydrogen peroxide were more benefit to degradation of methyl orange. The reaction condition was optimized. The optimum reaction process was as follow: iron amount of catalyst was 1.25%, the catalyst dosage and H2O2 concentration was 1 mg/L and 1.5 mg/L, and reaction temperature was 70 °C. The apparent activation energy (65 KJ/mol) was obtained according to the arrhenius formula, which was benefit to study the reaction mechanism.

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Shahroudbari, Isa, Yaghoub Sarrafi, and Yahya Zamani. "Study of carbon dioxide hydrogenation to hydrocarbons over iron-based Catalysts: Synergistic effect." Kataliz v promyshlennosti 21, no. 3 (May 17, 2021): 182. http://dx.doi.org/10.18412/1816-0387-2021-3-182.

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The full article will be published in the English version of the journal "Catalysis in Industry" No. 4, 2021.Hydrogenation of CO2 to CO and hydrocarbons is carried out over a wide range of catalysts. Group of VIIIB transition metals have proved high conversion and selectively for CO and methane. Meanwhile, low cost and effective catalysts are preferable in an industrial scale. In this work, the synergistic effect of iron content on the catalytic performance were investigated in carbon dioxide hydrogenation reaction. Incipient wetness impregnation procedure was used for the preparation of four γ-Al2O3 supported iron-based catalysts. BET, XRD, H2-TPR and TEM techniques were employed for the catalyst characterization. The evaluation of catalysts were carried out in a fixed bed reactor at the process conditions of temperature of 300 °C, pressure of 20 atm, H2 to CO2 ratio of 3 and GHSV of 3 nl.h–1·gCat–1. It was found that the promoter addition improves the activity of Fe catalyst for both Fischer – Tropsch synthesis (FTS) and Reverse Water Gas Shift (RWGS) reactions. The results showed that conversion of CO2 was from 15.6 to 35.6 % with major products of methane, C2 to C4, C5+ and CO. It was also found that impact of K and Ce promoters into iron catalyst showed the highest conversion and hydrocarbon yield due to the synergistic effect.

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Vono, Lucas L. R., Camila C. Damasceno, Jivaldo R. Matos, Renato F. Jardim, Richard Landers, Sueli H. Masunaga, and Liane M. Rossi. "Separation technology meets green chemistry: development of magnetically recoverable catalyst supports containing silica, ceria, and titania." Pure and Applied Chemistry 90, no. 1 (January 26, 2018): 133–41. http://dx.doi.org/10.1515/pac-2017-0504.

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AbstractMagnetic separation can be considered a green technology because it is fast, efficient, consumes low energy, and minimizes the use of solvents and the generation of waste. It has been successfully used in laboratory scale to facilitate supported catalysts’ handling, separation, recovery, and recycling. Only few materials are intrisically magnetic, hence the application of magnetic materials as catalyst supports has broaden the use of magnetic separation. Iron oxides, silica-coated iron oxides, and carbon-coated-cobalt are among the most studied catalyst supports; however, other metal oxide coatings, such as ceria and titania, are also very interesting for application in catalysis. Here we report the preparation of magnetically recoverable magnetic supports containing silica, ceria, and titania. We found that the silica shell protects the iron oxide core and allows the crystalization of ceria and titania at high temperature without compromising the magnetic properties of the catalyst supports.

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Yang, Qiao Wen, Peng Fei Li, Ying Zhu, Chen Ying, Jin Lei Zuo, Hai Jun Dan, and Shao He Shi. "Study on Catalysis Properties of Graphene Catalyst Loading Iron Oxide." Applied Mechanics and Materials 316-317 (April 2013): 1014–17. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.1014.

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The graphite oxide was synthesized with Hummers liquid-phase oxidation method in experiment, and then was reduced to graphene by sodium borohydride, the iron oxide was loaded by dipping method. The catalyst that made reacted in SCR reaction unit in laboratory, the catalysis properties of catalyst was investigated. The experiment results showed that graphene was flake nanometer sheet and presented transparent fold shape, its crystal structure was in order arrangement; the nature of graphene was close to that of raw graphite; their surface function groups were similar; Fe/graphene SCR catalysts had certain catalytic ability in the reaction, the NO conversion rate of catalyst was about 50% while the temperature range was from 200°C to 300°C.

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10

Selvi, E. Thamarai, G. Kavinilavu, and A. Subramani. "Recent Advances Review on Iron Complexes as Catalyst in Oxidation Reactions of Organic Compounds." Asian Journal of Chemistry 34, no. 8 (2022): 1921–38. http://dx.doi.org/10.14233/ajchem.2022.23704.

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The complexes of iron are found to be too reactive and are too diverse in their reactivity, when compared to the other neighbouring metals in the group. Iron complexes are used in various catalytic reactions such as oxygenation of C–H bonds, the oxidation of alcohols to aldehydes, ketones (or) carboxylic acids, the epoxidation or dihydroxylation of alkenes and oxidative coupling reactions. Efforts are taken to avoid certain disadvantages taking place during enzymatic catalysis such as the temperature and solvent sensitivity, narrow substrate scope, restricted accessibility and so on observed while using other catalysts via iron enzymes. This helped in the various synthesis of complex molecules by increase in the number of iron catalyst systems for the oxidation reactions.

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11

Okoye-Chine, Chike George, and Samuel Mubenesha. "The Use of Iron Ore as a Catalyst in Fischer–Tropsch Synthesis—A Review." Crystals 12, no. 10 (September 24, 2022): 1349. http://dx.doi.org/10.3390/cryst12101349.

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The use of iron ore as an alternative to conventional Fischer–Tropsch synthesis (FTS) iron catalyst has been identified as a way to achieve a cost-effective catalyst. In recent times, considerable progress has been made to build a strong case for iron ore as a viable alternative to traditional iron catalysts. Nevertheless, there are still opportunities to enhance the current iron ore low-temperature Fischer–Tropsch (LTFT) catalysts and pave the way for optimal performing catalysts. In this study, we thoroughly examined the various publications on iron ore catalysts used for FTS and highlighted the research gaps in the studies. The study identified the progress made so far, opportunities, and challenges regarding the use of iron ore as a catalyst in FTS. One of the critical areas that needs to be addressed from the review is establishing the deactivation pathways of these catalyst systems. The application of advanced spectroscopic and computational methods is also suggested to elucidate the relationship between the synthesis conditions, active catalytic sites, reaction intermediates, and catalytic performance to fabricate optimized iron ore LTFT catalysts.

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12

Jabalameli, Mahin, Yahya Zamani, Sahar Baniyaghoob, and Laleh Shirazi. "Study of Iron-Based Catalysts Performance in Fischer – Tropsch Synthesis: Temperature and Promoter Effect." Kataliz v promyshlennosti 23, no. 1 (January 17, 2023): 56. http://dx.doi.org/10.18412/1816-0387-2023-1-56.

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The full text of the article will be published in the English version of the journal "Catalysis in Industry" No. 1, 2023.The iron-based catalysts were prepared via wet-impregnation method. The composition of the final iron catalysts, regarding to the weight ratio is as follow 14%Fe/γ-Al2O3, 14%Fe/3%Cu/γ-Al2O3, 14%Fe/3%Sn/γ-Al2O3 and 14%Fe/3%Cu/1%Sn/γ-Al2O3. The catalysts were characterized using XRD, ICP, BET, H2-TPR, FE-SEM and EDX techniques. The catalytic activity was evaluated in a fixed bed reactor under 20 bar of pressure, H2/CO = 1, GHSV = 2 L/(gcat·h), in the temperature range of 270–300 °C. Then, the effect of temperature and promoters (Cu and Sn) on the catalyst performance were investigated. CO conversion and product selectivity were also calculated using the results of GC. The results showed that the Cu and Sn promoters increased the reduction rate of Fe2O3 by providing H2 dissociation sites. Higher temperatures were also shown to change the CO conversion and product selectivity. The selectivity of both methane and C2–C4 hydrocarbons decreased while the selectivity of C5+ increased because of simultaneous use of Cu and Sn for promoting iron catalyst. Sn promoter increased FT and WGS activities.

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13

Zhou, Haiqing, Fang Yu, Jingying Sun, Ran He, Shuo Chen, Ching-Wu Chu, and Zhifeng Ren. "Highly active catalyst derived from a 3D foam of Fe(PO3)2/Ni2P for extremely efficient water oxidation." Proceedings of the National Academy of Sciences 114, no. 22 (May 15, 2017): 5607–11. http://dx.doi.org/10.1073/pnas.1701562114.

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Commercial hydrogen production by electrocatalytic water splitting will benefit from the realization of more efficient and less expensive catalysts compared with noble metal catalysts, especially for the oxygen evolution reaction, which requires a current density of 500 mA/cm2 at an overpotential below 300 mV with long-term stability. Here we report a robust oxygen-evolving electrocatalyst consisting of ferrous metaphosphate on self-supported conductive nickel foam that is commercially available in large scale. We find that this catalyst, which may be associated with the in situ generated nickel–iron oxide/hydroxide and iron oxyhydroxide catalysts at the surface, yields current densities of 10 mA/cm2 at an overpotential of 177 mV, 500 mA/cm2 at only 265 mV, and 1,705 mA/cm2 at 300 mV, with high durability in alkaline electrolyte of 1 M KOH even after 10,000 cycles, representing activity enhancement by a factor of 49 in boosting water oxidation at 300 mV relative to the state-of-the-art IrO2 catalyst.

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14

Arabczyk, Walerian, Urszula Narkiewicz, Zofia Lendzion-Bieluń, Dariusz Moszyński, Iwona Pełech, Ewa Ekiert, Marcin Podsiadły, et al. "Utilization of spent iron catalyst for ammonia synthesis." Polish Journal of Chemical Technology 9, no. 3 (January 1, 2007): 108–13. http://dx.doi.org/10.2478/v10026-007-0067-y.

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Utilization of spent iron catalyst for ammonia synthesis Several methods of the utilization of spent iron catalyst for ammonia synthesis have been presented. The formation of iron nitrides of different stoichiometry by direct nitriding in ammonia in the range of temperatures between 350°C and 450°C has been shown. The preparation methods of carbon nanotubes and nanofibers where iron catalyst catalyse the decomposition of hydrocarbons have been described. The formation of magnetite embedded in a carbon material by direct oxidation of carburized iron catalyst has been also presented.

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Schoeneberger, Elsa M., and Gerrit A. Luinstra. "Investigations on the Ethylene Polymerization with Bisarylimine Pyridine Iron (BIP) Catalysts." Catalysts 11, no. 3 (March 23, 2021): 407. http://dx.doi.org/10.3390/catal11030407.

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The kinetics and terminations of ethylene polymerization, mediated by five bisarylimine pyridine (BIP) iron dichloride precatalysts, and activated by large amounts of methyl aluminoxane (MAO) was studied. Narrow distributed paraffins from initially formed aluminum polymeryls and broader distributed 1-polyolefins and (bimodal) mixtures, thereof, were obtained after acidic workup. The main pathway of olefin formation is beta-hydrogen transfer to ethylene. The rate of polymerization in the initial phase is inversely proportional to the co-catalyst concentration for all pre-catalysts; a first-order dependence was found on ethylene and catalyst concentrations. The inhibition by aluminum alkyls is released to some extent in a second phase, which arises after the original methyl groups are transformed into n-alkyl entities and the aluminum polymeryls partly precipitate in the toluene medium. The catalysis is interpretable in a mechanism, wherein, the relative rate of chain shuttling, beta-hydrogen transfer and insertion of ethylene are determining the outcome. Beta-hydrogen transfer enables catalyst mobility, which leads to a (degenerate) chain growth of already precipitated aluminum alkyls. Stronger Lewis acidic centers of the single site catalysts, and those with smaller ligands, are more prone to yield 1-olefins and to undergo a faster reversible alkyl exchange between aluminum and iron.

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Abrar, B., M. Halali, and A. Pourfathi. "Recovery of Nickel from Reformer Catalysts of Direct Reduction, Using the Pressurized Dissolving Method in Nitric Acid." Engineering, Technology & Applied Science Research 6, no. 5 (October 23, 2016): 1158–61. http://dx.doi.org/10.48084/etasr.731.

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In the process of direct reduction of iron pellet and production of sponge iron, NiO/Al2O3 act as a catalyst for the generation of carbon monoxide and hydrogen by vapor and natural gas. As an expensive material used in MIDREX method for steel units, this type of catalyst has major environmental problems after accumulation. The steel industry in Iran hopes to employ the MIDREX technique for the 80 percent of the 50 million tons of steel. Thus, the problem of spent catalysts will become a serious environmental challenge. Through the hydrometallurgy method, the present study investigates a possible solution to the problem of catalyst depot (due to heavy metals such as nickel) via nickel recovery, which may increase the possibility of selling or re-using the precious and expensive metal. The present research studied the Nickel recovery from spent catalysts of NiO/Al2O¬3 used in reduction gas reliefs of the production of sponge iron unit. In this study, the parameters of temperature, concentration, time and Rpm were studied using pressurized dissolving method. 100% efficiency was achieved at 140 °C for 120 minutes, nitric acid concentration of 1.5 mm, Rpm of 600 and 40 s/l 40 grams per liter.

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Ponce, Adrian. "Radionuclide-induced defect sites in iron-bearing minerals may have accelerated the emergence of life." Interface Focus 9, no. 6 (October 18, 2019): 20190085. http://dx.doi.org/10.1098/rsfs.2019.0085.

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The emergence of life on Earth (and elsewhere) must have occurred in a milieu that is far from equilibrium, such as at alkaline hydrothermal vents that would have harboured built-in gradients in temperature, redox potential and pH along with precipitated iron-bearing minerals capable of separating these gradients, concentrating reactants and catalysing requisite protobiotic reactions. Iron-bearing minerals such as mackinawite, greenalite and fougèrite have been investigated as catalysts for protobiotic reactions, including amino acid synthesis. In the field of heterogeneous catalysis, it is well known that defect sites in the crystal structure are often the most active sites for catalysis, and mineral catalysts that have been exposed to ionizing radiation are known to exhibit increased reactivity due to radiation-induced defect sites. In this work, we (i) review the literature on the radioactive environment of the Hadean era, (ii) highlight the role of radionuclide ionizing radiation from 238 U, 232 Th and 40 K in generating defect sites with high catalytic activity for the chemical evolution of organic molecules, and (iii) hypothesize that these processes accelerated the emergence of life.

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18

Sanchis, Rut, Daniel Alonso-Domínguez, Ana Dejoz, María Pico, Inmaculada Álvarez-Serrano, Tomás García, María López, and Benjamín Solsona. "Eco-Friendly Cavity-Containing Iron Oxides Prepared by Mild Routes as Very Efficient Catalysts for the Total Oxidation of VOCs." Materials 11, no. 8 (August 9, 2018): 1387. http://dx.doi.org/10.3390/ma11081387.

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Iron oxides (FeOx) are non-toxic, non-expensive and environmentally friendly compounds, which makes them good candidates for many industrial applications, among them catalysis. In the present article five catalysts based on FeOx were synthesized by mild routes: hydrothermal in subcritical and supercritical conditions (Fe-HT, Few200, Few450) and solvothermal (Fe-ST1 and Fe-ST2). The catalytic activity of these catalysts was studied for the total oxidation of toluene using very demanding conditions with high space velocities and including water and CO2 in the feed. The samples were characterized by X-ray diffraction (XRD), scanning and high-resolution transmission electron microscopy (SEM and HRTEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption isotherms. It was observed that the most active catalyst was a cavity-containing porous sample prepared by a solvothermal method with a relatively high surface area (55 m2 g−1) and constituted by flower-like aggregates with open cavities at the catalyst surface. This catalyst displayed superior performance (100% of toluene conversion at 325 °C using highly demanding conditions) and this performance can be maintained for several catalytic cycles. Interestingly, the porous iron oxides present not only a higher catalytic activity than the non-porous but also a higher specific activity per surface area. The high activity of this catalyst has been related to the possible synergistic effect of compositional, structural and microstructural features emphasizing the role of the surface area, the crystalline phase present, and the properties of the surface.

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Haslinger, Stefan, Alexander Pöthig, Mirza Cokoja, and Fritz E. Kühn. "Oxidative degradation of the organometallic iron(II) complex [Fe{bis[3-(pyridin-2-yl)-1H-imidazol-1-yl]methane}(MeCN)(PMe3)](PF6)2: structure of the ligand decomposition product trappedviacoordination to iron(II)." Acta Crystallographica Section C Structural Chemistry 71, no. 12 (November 27, 2015): 1096–99. http://dx.doi.org/10.1107/s2053229615021968.

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Iron is of interest as a catalyst because of its established use in the Haber–Bosch process and because of its high abundance and low toxicity. Nitrogen-heterocyclic carbenes (NHC) are important ligands in homogeneous catalysis and iron–NHC complexes have attracted increasing attention in recent years but still face problems in terms of stability under oxidative conditions. The structure of the iron(II) complex [1,1′-bis(pyridin-2-yl)-2,2-bi(1H-imidazole)-κN3][3,3′-bis(pyridin-2-yl-κN)-1,1′-methanediylbi(1H-imidazol-2-yl-κC2)](trimethylphosphane-κP)iron(II) bis(hexafluoridophosphate), [Fe(C17H14N6)(C16H12N6)(C3H9P)](PF6)2, features coordination by an organic decomposition product of a tetradentate NHC ligand in an axial position. The decomposition product, a C—C-coupled biimidazole, is trapped by coordination to still-intact iron(II) complexes. Insights into the structural features of the organic decomposition products might help to improve the stability of oxidation catalysts under harsh conditions.

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Liu, Zhaoyong, Zhongdong Zhang, Pusheng Liu, Jianing Zhai, and Chaohe Yang. "Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst." Journal of Nanotechnology 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/273859.

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FCC (Fluid Catalytic Cracking) catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst) exceeds 8000 μg/g.

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Britton, Luke, Jamie H. Docherty, Andrew P. Dominey, and Stephen P. Thomas. "Iron-Catalysed C(sp2)-H Borylation Enabled by Carboxylate Activation." Molecules 25, no. 4 (February 18, 2020): 905. http://dx.doi.org/10.3390/molecules25040905.

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Arene C(sp2)-H bond borylation reactions provide rapid and efficient routes to synthetically versatile boronic esters. While iridium catalysts are well established for this reaction, the discovery and development of methods using Earth-abundant alternatives is limited to just a few examples. Applying an in situ catalyst activation method using air-stable and easily handed reagents, the iron-catalysed C(sp2)-H borylation reactions of furans and thiophenes under blue light irradiation have been developed. Key reaction intermediates have been prepared and characterised, and suggest two mechanistic pathways are in action involving both C-H metallation and the formation of an iron boryl species.

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Li, Weizhen, Xuebing Zhang, Tao Wang, Xiaoyu Zhang, Linlin Wei, Quan Lin, Yijun Lv, and Zhuowu Men. "The Effect of Chlorine Modification of Precipitated Iron Catalysts on Their Fischer–Tropsch Synthesis Properties." Catalysts 12, no. 8 (July 24, 2022): 812. http://dx.doi.org/10.3390/catal12080812.

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Precipitated iron Fischer–Tropsch synthesis catalysts impregnated with chlorine were prepared and their Fischer–Tropsch synthesis performances were tested in a 1 L stirred tank reactor. The results showed that the chlorine modification had a significant influence on the Fischer–Tropsch synthesis performance of the precipitated iron catalyst. Compared with the catalyst without the chlorine modification, the catalyst containing about 0.1 wt% chlorine was deactivated by about 40% and the catalyst containing about 1 wt% chlorine was deactivated by about 65%. The textural properties, phase, reduction properties, and chlorine adsorption state of the catalysts before and after the Fischer–Tropsch synthesis were characterized. The strong interaction between chlorine and iron in the catalyst hindered the reduction and carbonization of the catalyst, which was the reason for the deactivation of the catalyst caused by the chlorine modification.

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Khazzal Hummadi, Khalid, Karim H. Hassan, and Phillip C. H. Mitchell. "Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol." Journal of Engineering Research [TJER] 6, no. 1 (June 1, 2009): 1. http://dx.doi.org/10.24200/tjer.vol6iss1pp1-7.

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The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK), 10 atm (1013 kPa), with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III) molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a commercial catalyst; maximum selectivity (82.3%) was obtained at 573oK when the conversion was 59.7%. Catalysts prepared by reacting iron (III) and molybdate by kneading or precipitation followed by evaporation, omitting a filtration stage, were less active and less selective. The selectivity-activity relationships of these catalysts as a function of temperature were discussed in relation to the method of preparation, surface areas and composition. By combing this catalytic data with data from the patent literature we demonstrate a synergy between iron and molybdenum in regard to methanol oxidation to formaldehyde; the optimum composition corresponded to an iron mole fraction 0.2-0.3. The selectivity to formaldehyde was practically constant up to an iron mole fraction 0.3 and then decreased at higher iron concentrations. The iron component can be regarded as the activity promoter. The iron molybdate catalysts can thus be related to other two-component MoO3-based selective oxidation catalysts, e.g. bismuth and cobalt molybdates. The iron oxide functions as a relatively basic oxide abstracting, in the rate-controlling step, a proton from the methyl of a bound methoxy group of chemisorbed methanol. It was proposed that a crucial feature of the sought after iron(III) molybdate catalyst is the presence of -O-Mo-O-Fe-O-Mo-O- groups as found in the compound Fe2(MoO4)3 and for Fe3+ well dispersed in MoO3 generally. At the higher iron(III) concentrations the loss of selectivity is due to the presence of iron oxide patches or particles which catalyze the total oxidation of methanol, and the loss of activity to blocking of molybdenum sites.

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Pereira, M. C., L. C. A. Oliveira, and E. Murad. "Iron oxide catalysts: Fenton and Fentonlike reactions – a review." Clay Minerals 47, no. 3 (September 2012): 285–302. http://dx.doi.org/10.1180/claymin.2012.047.3.01.

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AbstractIron is the fourth most common element by mass in the Earth's crust and forms compounds in several oxidation states. Iron (hydr)oxides, some of which form inherently and exclusively in the nanometre-size range, are ubiquitous in nature and readily synthesized. These facts add up to render many Fe (hydr)oxides suitable as catalysts, and it is hardly surprising that numerous studies on the applications of Fe (hydr)oxides in catalysis have been published. Moreover, the abundant availability of a natural Fe source from rocks and soils at minimal cost makes the potential use of these as heterogeneous catalyst attractive.Besides those Fe (hydr)oxides that are inherently nanocrystalline (ferrihydrite, Fe5HO8.4H2O, and feroxyhyte, δ’-FeOOH), magnetite (Fe3O4) is often used as a catalyst because it has a permanent magnetization and contains Fe in both the divalent and trivalent states. Hematite, goethite and lepidocrocite have also been used as catalysts in their pure forms, doped with other cations, and as composites with carbon, alumina and zeolites among others.In this review we report on the use of synthetic and natural Fe (hydr)oxides as catalysts in environmental remediation procedures using an advanced oxidation process, more specifically the Fenton-like system, which is highly efficient in generating reactive species such as hydroxyl radicals, even at room temperature and under atmospheric pressure. The catalytic efficiency of Fe (hydr)oxides is strongly affected by factors such as the Fe oxidation state, surface area, isomorphic substitution of Fe by other cations, pH and temperature.

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Rusanen, Annu, Riikka Kupila, Katja Lappalainen, Johanna Kärkkäinen, Tao Hu, and Ulla Lassi. "Conversion of Xylose to Furfural over Lignin-Based Activated Carbon-Supported Iron Catalysts." Catalysts 10, no. 8 (July 22, 2020): 821. http://dx.doi.org/10.3390/catal10080821.

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In this study, conversion of xylose to furfural was studied using lignin-based activated carbon-supported iron catalysts. First, three activated carbon supports were prepared from hydrolysis lignin with different activation methods. The supports were modified with different metal precursors and metal concentrations into five iron catalysts. The prepared catalysts were studied in furfural production from xylose using different reaction temperatures and times. The best results were achieved with a 4 wt% iron-containing catalyst, 5Fe-ACs, which produced a 57% furfural yield, 92% xylose conversion and 65% reaction selectivity at 170 °C in 3 h. The amount of Fe in 5Fe-ACs was only 3.6 µmol and using this amount of homogeneous FeCl3 as a catalyst, reduced the furfural yield, xylose conversion and selectivity. Good catalytic activity of 5Fe-ACs could be associated with iron oxide and hydroxyl groups on the catalyst surface. Based on the recycling experiments, the prepared catalyst needs some improvements to increase its stability but it is a feasible alternative to homogeneous FeCl3.

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26

Liu, Yan, Guangyu Xie, Guoyu Li, Jingye Cui, Chuang Li, Hao Xu, Yating Lu, Qi Jin, Daixi Zhou, and Xinjiang Hu. "Iron Carbon Catalyst Initiated the Generation of Active Free Radicals without Oxidants for Decontamination of Methylene Blue from Waters." Catalysts 12, no. 4 (March 30, 2022): 388. http://dx.doi.org/10.3390/catal12040388.

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In conventional oxidation technologies for treatment of contaminated waters, secondary pollution of the aqueous environment often occurs because of the additional oxidants generated during the process. To avoid this problem, Fe/NG catalyst composites without additives were developed in this study for decontamination of methylene blue (MB) from waters. The Fe/NG catalyst, composed of carbon nitride and iron chloride (FeCl3·6H2O), was prepared by high temperature pyrolysis. It is an exceptionally efficient, recoverable, and sustainable catalyst for degradation of organic matter. The morphological characteristics, chemical structure, and surface properties of the catalyst composites were investigated. The catalyst exhibited high MB removal efficiency (100%) within 30 min under ambient temperature and dark conditions. The experiments indicated that an MB degradation effect was also applicable under most acid–base conditions (pH = 2–10). The characterization results using electron spin resonance and analysis of intermediate products demonstrated that free radicals such as ·OH and ·O2− were produced from the Fe/NG composites in the heterogeneous system, which resulted in the high MB degradation efficiency. Moreover, the catalysis reaction generated reducing substances, triggering iron carbon micro-electrolysis to spontaneously develop a microcurrent, which assisted the degradation of MB. This study demonstrates the feasibility of Fe/NG catalysts that spontaneously generate active species for degrading pollutants in an aqueous environment at normal temperature, providing an attractive approach for treating organic-contaminated waters.

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Monkcom, Emily C., Pradip Ghosh, Emma Folkertsma, Hidde A. Negenman, Martin Lutz, and Robertus J. M. Klein Gebbink. "Bioinspired Non-Heme Iron Complexes: The Evolution of Facial N, N, O Ligand Design." CHIMIA International Journal for Chemistry 74, no. 6 (June 24, 2020): 450–66. http://dx.doi.org/10.2533/chimia.2020.450.

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Iron-containing metalloenzymes that contain the 2-His-1-Carboxylate facial triad at their active site are well known for their ability to activate molecular oxygen and catalyse a broad range of oxidative transformations. Many of these reactions are synthetically challenging, and developing small molecular iron-based catalysts that can achieve similar reactivity and selectivity remains a long-standing goal in homogeneous catalysis. This review focuses on the development of bioinspired facial N,N,O ligands that model the 2-His-1-Carboxylate facial triad to a greater degree of structural accuracy than many of the polydentate N-donor ligands commonly used in this field. By developing robust, well-defined N,N,O facial ligands, an increased understanding could be gained of the factors governing enzymatic reactivity and selectivity.

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Savostyanov, Alexander P., Roman E. Yakovenko, Grigory B. Narochny, Evgenia V. Nepomnyashchikh, and Sergey A. Mitchenko. "BIFUNCTIONAL СО/SIO2-Fe-ZSM-5-Al2O3 CATALYSTS FOR SYNTHESIS OF HYDROCARBONS OF ENGINE FRACTIONS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 8 (August 20, 2019): 139–46. http://dx.doi.org/10.6060/ivkkt.20196208.5905.

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The process of obtaining motor fractions of hydrocarbons on bifunctional Со/SiO2-Fe-ZSM-5-Al2O3, catalysts obtained by mixing has been studied. The effect of the method of introducing iron into a catalyst (in the form of reduced iron and its nitrate) at the molding stage is studied. The catalysts were tested in a continuous mode for 30 h at a gas volume velocity of 1000 h-1, a pressure of 2 MPa and a temperature of 240 ° C. It is shown that when iron is introduced in the form of a reduced powder, the temperature gradient in the catalyst bed decreases, and the selectivity for C5+ hydrocarbons increases by 6% in comparison with the catalyst sample without the addition of iron. It has been established that the introduction of iron into the catalyst in the form of a nitrate salt is a less effective method. It blocks the operation of polymerization and acid sites of bifunctional catalysts, contributes to a reduction in CO conversion and selectivity for C5+ hydrocarbons. It is shown that the introduction of iron significantly changes the group composition and molecular-mass distribution of the produced hydrocarbons - the shares of saturated hydrocarbons are increases, predominantly of a linear structure, the yield of olefins decreases. The obtained C5+ hydrocarbons mainly consist of gasoline and diesel fractions. The introduction of iron promotes an increase in the content of diesel fractions in synthesis products. Thus, with the introduction of iron in the form of a nitrate salt, the content of the diesel fraction increased by 1.2 times in comparison with the sample of a catalyst without iron.

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Martin, Daniel J., Brandon Q. Mercado, and James M. Mayer. "Combining scaling relationships overcomes rate versus overpotential trade-offs in O2 molecular electrocatalysis." Science Advances 6, no. 11 (March 2020): eaaz3318. http://dx.doi.org/10.1126/sciadv.aaz3318.

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The development of advanced chemical-to-electrical energy conversions requires fast and efficient electrocatalysis of multielectron/multiproton reactions, such as the oxygen reduction reaction (ORR). Using molecular catalysts, correlations between the reaction rate and energy efficiency have recently been identified. Improved catalysis requires circumventing the rate versus overpotential trade-offs implied by such “scaling relationships.” Described here is an ORR system—using a soluble iron porphyrin and weak acids—with the best reported combination of rate and efficiency for a soluble ORR catalyst. This advance is achieved not by “breaking” scaling relationships but rather by combining two of them. Key to this behavior is a polycationic ligand, which enhances anionic ligand binding and changes the catalyst E1/2. These results show how combining scaling relationships is a powerful way toward improved electrocatalysis.

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30

Pour, Ali Nakhaei, and Fatemeh Dolati. "Activation Energies for Chain Growth Propagation and Termination in Fischer–Tropsch Synthesis on Iron Catalyst as a Function of Catalyst Particle Size." Progress in Reaction Kinetics and Mechanism 41, no. 4 (November 2016): 371–84. http://dx.doi.org/10.3184/174751916x14701459562861.

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The influence of the catalyst particle size in determining Fischer–Tropsch synthesis (FTS) performance for nano-structured iron catalysts was investigated. The catalysts were prepared by a microemulsion method and to achieve a series of catalysts with different iron particle size, the water-to-surfactant molar ratio (W/S) in the microemulsion system varied from 4 to 12. The results demonstrate that by decreasing the levels of active phase of the iron catalyst, the termination rates for chain growth are increased compared to the propagation rates. In addition, the activation energy for chain propagation is lower than for chain termination, and this difference (Et – Ep) for the hydrocarbon product distributions which is characterised by α1, is lower than the hydrocarbon product distribution which is characterised by α2 The results indicate the H2 concentration on the catalyst surface is decreased by increasing the catalyst particle size. Thus, the dependence of α (α1, and/or α2) on H2 partial pressures is increased by decreasing of catalyst particle size and the dependence of α2 on H2 partial pressures is weaker than for α1.

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31

Ollevier, Thierry. "Iron bis(oxazoline) complexes in asymmetric catalysis." Catalysis Science & Technology 6, no. 1 (2016): 41–48. http://dx.doi.org/10.1039/c5cy01357g.

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Asymmetric reactions catalyzed by iron complexes have attracted considerable attention because iron is a ubiquitous, inexpensive, and environmentally benign metal. This overview charts the development and application of chiral iron bis(oxazoline) and pyridine-2,6-bis(oxazoline) catalysts through their most prominent and innovative uses in asymmetric catalysis, especially in Lewis acid and oxidation catalysis.

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Li, Zhaoyang, Geng Chen, Zhenghua Shao, Haonan Zhang, and Xiujuan Guo. "The Effect of Iron Content on the Ammonia Selective Catalytic Reduction Reaction (NH3-SCR) Catalytic Performance of FeOx/SAPO-34." International Journal of Environmental Research and Public Health 19, no. 22 (November 10, 2022): 14749. http://dx.doi.org/10.3390/ijerph192214749.

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Iron-based catalysts are regarded as promising candidates for the ammonia selective catalytic reduction reaction (NH3-SCR) which show good catalytic activity at medium and high temperatures, whereas SAPO-34 molecular sieves have a micro-pore structure and are ideal catalyst carriers. In this paper, four FeOx/SAPO-34 molecular sieve catalysts with different iron contents (Fe = 1%, 2%, 3%, 4%) were prepared using an impregnation method. The effect of iron content on the surface properties and catalytic activity was investigated by a series of characterization techniques including XRD, SEM, BET, XPS, H2-TPR and NH3-TPD. Iron species in the FeOx/SAPO-34 catalysts exist in the form of isolated iron ions or well-dispersed small crystals and iron oxide species clusters. With the addition of iron content, the integrity of CHA (chabazite) zeolite structure remained, but the crystallinity was affected. The FeOx/SAPO-34 catalyst with 3% Fe loading showed a relatively flat surface with no large-diameter particles and strong oxidation-reduction ability. Meanwhile, more acidic sites are exposed, which accelerated the process of catalytic reaction. Thus, the FeOx/SAPO-34 catalyst with 3% Fe showed the best NO conversion performance among the four catalysts prepared and maintained more than 90% NO conversion efficiency in a wide temperature range from 310 °C to 450 °C.

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Talla, Harli, and Herman Tjolleng Taba. "Pencairan Batubara Peringkat Rendah Papua Menggunakan Katalis Bijih Besi." Jurnal Rekayasa Kimia & Lingkungan 12, no. 2 (December 26, 2017): 94. http://dx.doi.org/10.23955/rkl.v12i2.8819.

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Low rank coal utilization often adversely affects the equipment used. Distinct with coal liquefaction technology that prioritizes the use of low rank coal. This condition encourages this research, with the aim of observing the liquid potential of low rank Papuan coal by using iron ore catalysts. Papua low rank coal is liquefied on the autoclave 5 liter with iron ore catalyst and antrasen as solvent. Operating conditions consist of temperature of 400ºC and holding time of 60 minutes. The result of conversion of the three samples without catalyst is only in the range of 65.72-66,45 %, whereas the conversion with iron ore catalysts ranged from 88.63-89.94 % and oil yield between 62.11-63,34%. This result also shows the contribution of iron ore catalyst to increase the conversions that averaged 23.04 %.

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Meng, Fanhui, Pengzhan Zhong, Zhong Li, Xiaoxi Cui, and Huayan Zheng. "Surface Structure and Catalytic Performance of Ni-Fe Catalyst for Low-Temperature CO Hydrogenation." Journal of Chemistry 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/534842.

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Catalysts 16NixFe/Al2O3(xis 0, 1, 2, 4, 6, 8) were prepared by incipient wetness impregnation method and the catalytic performance for the production of synthetic natural gas (SNG) from CO hydrogenation in slurry-bed reactor were studied. The catalysts were characterized by BET, XRD, UV-Vis DRS, H2-TPR, CO-TPD, and XPS, and the results showed that the introduction of iron improved the dispersion of Ni species, weakened the interaction between Ni species and support and decreased the reduction temperature and that catalyst formed Ni-Fe alloy when the content of iron exceeded 2%. Experimental results revealed that the addition of iron to the catalyst can effectively improve the catalytic performance of low-temperature CO methanation. Catalyst 16Ni4Fe/Al2O3with the iron content of 4% exhibited the best catalytic performance, the conversion of CO and the yield of CH4reached 97.2% and 84.9%, respectively, and the high catalytic performance of Ni-Fe catalyst was related to the property of formed Ni-Fe alloy. Further increase of iron content led to enhancing the water gas shift reaction.

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35

Rydel-Ciszek, Katarzyna, Tomasz Pacześniak, Izabela Zaborniak, Paweł Błoniarz, Karolina Surmacz, Andrzej Sobkowiak, and Paweł Chmielarz. "Iron-Based Catalytically Active Complexes in Preparation of Functional Materials." Processes 8, no. 12 (December 20, 2020): 1683. http://dx.doi.org/10.3390/pr8121683.

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Iron complexes are particularly interesting as catalyst systems over the other transition metals (including noble metals) due to iron’s high natural abundance and mediation in important biological processes, therefore making them non-toxic, cost-effective, and biocompatible. Both homogeneous and heterogeneous catalysis mediated by iron as a transition metal have found applications in many industries, including oxidation, C-C bond formation, hydrocarboxylation and dehydration, hydrogenation and reduction reactions of low molecular weight molecules. These processes provided substrates for industrial-scale use, e.g., switchable materials, sustainable and scalable energy storage technologies, drugs for the treatment of cancer, and high molecular weight polymer materials with a predetermined structure through controlled radical polymerization techniques. This review provides a detailed statement of the utilization of homogeneous and heterogeneous iron-based catalysts for the synthesis of both low and high molecular weight molecules with versatile use, focusing on receiving functional materials with high potential for industrial application.

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36

Liao, Yitao, Tao Liu, Huihui Zhao, and Xionghou Gao. "A Comparison of Laboratory Simulation Methods of Iron Contamination for FCC Catalysts." Catalysts 11, no. 1 (January 14, 2021): 104. http://dx.doi.org/10.3390/catal11010104.

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Two different methods of simulating iron contamination in a laboratory were studied. The catalysts were characterized using X-ray diffraction, N2 adsorption–desorption, and SEM-EDS. The catalyst performance was evaluated using an advanced cracking evaluation device. It was found that iron was evenly distributed in the catalyst prepared using the Mitchell impregnation method and no obvious iron nodules were found on the surface of the catalyst. Iron on the impregnated catalyst led to a strong dehydrogenation capacity and a slight decrease in the conversion and bottoms selectivity. The studies also showed that iron was mainly in the range of 1–5 μm from the edge of the catalyst prepared using the cycle deactivation method. Iron nodules could be easily observed on the surface of the catalyst. The retention of the surface structure in the alumina-rich areas and the collapse of the surface structure in the silica-rich areas resulted in a continuous nodule morphology, which was similar to the highly iron-contaminated equilibrium catalyst. Iron nodules on the cyclic-deactivated catalyst led to a significant decrease in conversion, an extremely high bottoms yield, and a small increase in the dehydrogenation capacity. The nodules and distribution of iron on the equilibrium catalyst could be better simulated by using the cyclic deactivation method.

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37

Chernyak, Sergei A., Dmitrii N. Stolbov, Konstantin I. Maslakov, Ruslan V. Kazantsev, Oleg L. Eliseev, Dmitry O. Moskovskikh, and Serguei V. Savilov. "Graphene Nanoflake- and Carbon Nanotube-Supported Iron–Potassium 3D-Catalysts for Hydrocarbon Synthesis from Syngas." Nanomaterials 12, no. 24 (December 19, 2022): 4491. http://dx.doi.org/10.3390/nano12244491.

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Transformation of carbon oxides into valuable feedstocks is an important challenge nowadays. Carbon oxide hydrogenation to hydrocarbons over iron-based catalysts is one of the possible ways for this transformation to occur. Carbon supports effectively increase the dispersion of such catalysts but possess a very low bulk density, and their powders can be toxic. In this study, spark plasma sintering was used to synthesize new bulk and dense potassium promoted iron-based catalysts, supported on N-doped carbon nanomaterials, for hydrocarbon synthesis from syngas. The sintered catalysts showed high activity of up to 223 μmolCO/gFe/s at 300–340 °C and a selectivity to C5+ fraction of ~70% with a high portion of olefins. The promising catalyst performance was ascribed to the high dispersity of iron carbide particles, potassium promotion of iron carbide formation and stabilization of the active sites with nitrogen-based functionalities. As a result, a bulk N-doped carbon-supported iron catalyst with 3D structure was prepared, for the first time, by a fast method, and demonstrated high activity and selectivity in hydrocarbon synthesis. The proposed technique can be used to produce well-shaped carbon-supported catalysts for syngas conversion.

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38

Qi, Miao, Benny Kia Jia Chew, Kwai Ga Yee, Zhong-Xing Zhang, David J. Young, and T. S. Andy Hor. "A catch–release catalysis system based on supramolecular host–guest interactions." RSC Advances 6, no. 28 (2016): 23686–92. http://dx.doi.org/10.1039/c6ra01846g.

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39

Zanatta, L. D., I. A. Barbosa, F. B. Zanardi, P. C. de Sousa Filho, L. B. Bolzon, A. P. Ramos, O. A. Serra, and Y. Iamamoto. "Hydrocarbon oxidation by iron-porphyrin immobilized on SBA-15 as biomimetic catalyst: role of silica surface." RSC Advances 6, no. 106 (2016): 104886–96. http://dx.doi.org/10.1039/c6ra18395f.

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Zhang, Lian Zi, and Hao Yuan Sun. "Development of Catalysts for Synthesizing Methanol from Syngas." Materials Science Forum 1053 (February 17, 2022): 165–69. http://dx.doi.org/10.4028/p-0eor9r.

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At present, methanol is one of the most basic organic chemical raw materials and energy storage media. With the development of chemical technology and energy storage technology, its application becomes more and more extensive, and the methanol market prospects are unlimited. Industrial-scale methanol is generally prepared by using synthesis gas containing hydrogen, carbon monoxide, and carbon dioxide as raw materials and reacting under a certain pressure, temperature, and catalyst. Therefore, the development of the methanol industry largely depends on the development of catalysts and the improvement of their performance. Metal catalysts are mainly used in the industry for reaction. This article reviews several metal catalysts used to synthesize methanol from syngas. Copper-based and iron-based catalysts are widely used, and the emerging rhodium and its ligand catalysts exhibit good catalytic performance in low-temperature catalysis. In the future, the scientific research team will focus on in-depth research on preparation methods, active centers, catalytic reaction kinetics, durability, metal ligands, raw material prices, etc., to lay a solid foundation for the industrial application of syngas to methanol in advance.

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Moccia, Fabio, Luca Rigamonti, Alessandro Messori, Valerio Zanotti, and Rita Mazzoni. "Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization." Molecules 26, no. 9 (May 6, 2021): 2728. http://dx.doi.org/10.3390/molecules26092728.

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Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an FeII-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, FeIII ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C–H bond activation.

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Pantupho, Waenkaew, Arthit Neramittagapong, Nuttawut Osakoo, Jatuporn Wittayakun, and Sirinuch Loiha. "The Effects of Preparation Methods on Iron Structures of Iron-Supported HZSM-5 and their Catalytic Performance for Methanol Dehydration." Key Engineering Materials 723 (December 2016): 633–39. http://dx.doi.org/10.4028/www.scientific.net/kem.723.633.

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Iron-supported HZSM-5 catalysts were prepared by hydrothermal (Fe-HZSM-5_HYD) and impregnation methods (Fe/HZSM-5_IMP). The active species of binuclear-iron complex and iron-substituted zeolite framework, confirmed by EXAFS analysis, were observed on Fe/HZSM-5_IMP and Fe-HZSM-5_HYD, respectively. The catalysts were used for production of dimethyl ether (DME) by methanol dehydration at 200-350 °C using fixed bed flow reactor. Fe/HZSM-5_IMP showed higher catalytic conversion than Fe-HZSM-5_HYD. However, the Fe/HZSM-5_IMP catalyst was less selective to DME product and strongly deactivated for 24h. The deactivation might due to transformation of binuclear-iron to the a-iron site which was strong acidic strengh. The iron-substituted zeolite framework of Fe-HZSM-5_HYD showed high stability toward methanol dehydration. Moreover, the catalyst showed advantages of good selective to DME and low carbon deposition on surface. These results suggested that the iron-substituted zeolite framework structure could improve catalytic performance for mrthanol dehydration.

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Sirikulbodee, Paphatsara, Monrudee Phongaksorn, Thana Sornchamni, Tanakorn Ratana, and Sabaithip Tungkamani. "Effect of Different Iron Phases of Fe/SiO2 Catalyst in CO2 Hydrogenation under Mild Conditions." Catalysts 12, no. 7 (June 25, 2022): 698. http://dx.doi.org/10.3390/catal12070698.

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The effect of different active phases of Fe/SiO2 catalyst on the physio-chemical properties and the catalytic performance in CO2 hydrogenation under mild conditions (at 220 °C under an ambient pressure) was comprehensively studied in this work. The Fe/SiO2 catalyst was prepared by an incipient wetness impregnation method. Hematite (Fe2O3) in the calcined Fe/SiO2 catalyst was activated by hydrogen, carbon monoxide, and hydrogen followed by carbon monoxide, to form a metallic iron (Fe/SiO2-h), an iron carbide (Fe/SiO2-c), and a combination of a metallic iron and an iron carbide (Fe/SiO2-hc), respectively. All activated catalysts were characterized by XRD, Raman spectroscopy, N2 adsorption–desorption, H2-TPR, CO-TPR, H2-TPD, CO2-TPD, CO-TPD, NH3-TPD, and tested in a CO2 hydrogenation reaction. The different phases of the Fe/SiO2 catalyst are formed by different activation procedures and different reducing agents (H2 and CO). Among three different activated catalysts, the Fe/SiO2-c provides the highest CO2 hydrogenation performance in terms of maximum CO2 conversion, as well as the greatest selectivity toward long-chain hydrocarbon products, with the highest chain growth probability of 0.7. This is owing to a better CO2 and CO adsorption ability and a greater acidity on the carbide form of the Fe/SiO2-c surface, which are essential properties of catalysts for polymerization in FTs.

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Bhuana, Donny, Junshe Zhang, Fanxing Li, Matthew Cooper, and Timothy Brantley. "Development of Hybrid Fischer-Tropsch Synthesis Catalysts for Direct Production of Synthetic Gasoline from Coal-Based Syngas: An Indonesian Perspective." Modern Applied Science 9, no. 7 (July 1, 2015): 47. http://dx.doi.org/10.5539/mas.v9n7p47.

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The Fischer-Tropsch Synthesis (FTS) represents an environmentally friendly method for producing liquid fuelfrom coal-based syngas via the hydrogenation of carbon monoxide. In order for such a process to be feasible,better catalysts that are capable of enhancing the reaction performance are required. In response to these needs,new catalysts were investigated and introduced in this work. The incorporation of zeolite into the iron based FTScatalyst was expected to help refine the hydrocarbon products and shift the product distribution from the typicalFTS product range to the middle iso-paraffins, which is a gasoline range, and eventually increase the yield of theliquid fuel. This study aims to develop catalyst for producing liquid fuel, particularly gasoline, from carbonmonoxide and hydrogen. The pH of the catalysts was found to have significant effect on the catalytic activity dueto its ability to control the amount of promoter to be precipitated in the catalyst, which results in a lowerreduction temperature. Physically mixing the iron based FTS catalyst with zeolite was found to have little effecton the catalytic activity and the product distribution, apart from slightly increasing the selectivity of iso-paraffins,which is the indication of isomerization activity. Coating of zeolite onto the iron based FTS catalyst to form acore-shell structure was intended to enhance the ease of migration of the reactant and thus increasing thecatalytic activity and shifting the product distribution towards the gasoline range. While zeolite shell has beensuccessfully coated uniformly on the iron based core using hydrothermal synthesis technique, the formation ofthick zeolite shell might have blocked the active FTS sites on the iron based catalyst to some extent and isbelieved to have contributed to the low activity of the core-shell catalyst.

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Kostuch, Aldona, Joanna Gryboś, Szymon Wierzbicki, Zbigniew Sojka, and Krzysztof Kruczała. "Selectivity of Mixed Iron-Cobalt Spinels Deposited on a N,S-Doped Mesoporous Carbon Support in the Oxygen Reduction Reaction in Alkaline Media." Materials 14, no. 4 (February 9, 2021): 820. http://dx.doi.org/10.3390/ma14040820.

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One of the practical efforts in the development of oxygen reduction reaction (ORR) catalysts applicable to fuel cells and metal-air batteries is focused on reducing the cost of the catalysts production. Herein, we have examined the ORR performance of cheap, non-noble metal based catalysts comprised of nanosized mixed Fe-Co spinels deposited on N,S-doped mesoporous carbon support (N,S-MPC). The effect of the chemical and phase composition of the active phase on the selectivity of catalysts in the ORR process in alkaline media was elucidated by changing the iron content. The synthesized materials were thoroughly characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). Detailed S/TEM/EDX and Raman analysis of the phase composition of the synthesized ORR catalysts revealed that the dominant mixed iron-cobalt spinel is accompanied by minor fractions of bare cobalt and highly dispersed spurious iron oxides (Fe2O3 and Fe3O4). The contribution of individual phases and their degree of agglomeration on the carbon support directly influence the selectivity of the obtained catalysts. It was found that the mixed iron-cobalt spinel single phase gives rise to significant improvement of the catalyst selectivity towards the desired 4e− reaction pathway, in comparison to the reference bare cobalt spinel, whereas spurious iron oxides play a negative role for the catalyst selectivity.

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Chen, Lyufei, Emily Costa, Pradheep Kileti, Rina Tannenbaum, Jake Lindberg, and Devinder Mahajan. "Sonochemical Synthesis of Silica-Supported Iron Oxide Nanostructures and Their Application as Catalysts in Fischer–Tropsch Synthesis." Micro 2, no. 4 (November 21, 2022): 632–48. http://dx.doi.org/10.3390/micro2040042.

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The emphasis on climate change requires processes to be more efficient to minimize CO2 emissions, and nanostructured materials as catalysts could play a crucial role due to their high surface area per unit volume. Herein, we report the synthesis of silica microspheres (450–600 nm) using a modified Stober process, on which iron oxide clusters were deposited by sonolysis of iron pentacarbonyl to yield a nanostructured iron material (Si-Fe). A suite of spectroscopic techniques was used to characterize the synthesized materials. The BET surface area of freshly prepared Stober silica was 8.00 m2/g, and the Si-Fe material was 24.0 m2/g. Iron is commercially used as a Fischer–Tropsch (F–T) catalyst due to its low cost. However, catalyst attrition causes catalyst loss and lower product quality. In this study, the synthesized Si-Fe materials were evaluated for F–T synthesis to address these challenges. For comparison, two commercial materials, UCI (silica-supported micron-sized iron oxide) and BASF (unsupported nanosized iron oxide), were also evaluated. All three materials were first activated by pretreatment with either CO or synthesis gas (a mixture of CO and H2) for 24 h, then evaluated for quick screening in batch mode for F–T synthesis in a Parr batch reactor at three temperatures: 493 K, 513 K, and 533 K. The F–T data at 513 K showed that the CO-pretreated Si-Fe catalyst demonstrated lower CO2 (<0.5%), lower CH4 (<0.5%), and higher (>58%) C8–C20 selectivity (mol% C) to hydrocarbons, surpassing both reference catalysts. The temperature dependence data for Si-Fe: 17.4%, 58.3%, and 54.9% at 493 K, 513 K, and 533 K, respectively, showed that the hydrocarbon yield maximized at 513 K. The surface area increased to 27.9 m2/g for the CO-reduced Si-Fe catalyst after the F–T reaction at 513 K. The morphology and structural change of catalysts, before and after the F–T runs, were imaged. Of all the catalysts evaluated, the SEM–EDS data analysis showed the least carbon deposition on the CO-treated Si-Fe catalyst after the F–T reaction at 513 K and minimized CO2, a greenhouse gas. This could pave the way for selecting nanomaterials as F–T catalysts that effectively operate at lower temperatures and produce negligible CO2 by minimizing water-gas-shift (WGS) activity.

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Chen, Lei Shan, and Cun Jing Wang. "Synthesis of Carbon Onions with High Purity by Chemical Vapor Deposition." Advanced Materials Research 641-642 (January 2013): 43–46. http://dx.doi.org/10.4028/www.scientific.net/amr.641-642.43.

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Nano-carbon materials were synthesized by decomposing acetylene at 400 °C using iron supported on alumina as catalyst. The catalysts contain about 0.3 and 5.2 wt% iron. The products were refluxed in concentrated HCl at 80°C for 36 h in order to remove the catalyst support. The samples were examined by transmission electron microscopy and X-ray diffraction. The results show that carbon onions surrounding Fe3C core were obtained using the catalyst containing 0.3 wt% iron and these carbon onions had a structure of stacked graphitic fragments, with diameters in the range 15-50 nm.

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Pour, Ali Nakhaei, and Seyed Majed Modaresi. "Methane Formation in Fischer-Tropsch Synthesis: Role of Nanosized Catalyst Particles." Journal of Nano Research 35 (October 2015): 39–54. http://dx.doi.org/10.4028/www.scientific.net/jnanor.35.39.

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Concepts of the surface excess energy in the present work have been applied to explain the methane formation in Fischer-Tropsch synthesis by iron catalysts. A series of iron oxide particles doped by adding copper and lanthanum were prepared as a catalyst via precipitation by microemulsion method. Size dependent kinetic expressions for methane formation were derived and evaluated using experimental results. Experimental results show that the methane formation is increased by decreasing the catalyst particle size. The value of surface tension energy (σ) for iron catalyst is calculated in range of 0.047-0.015 J/m2in methane formation mechanism. This value is lower than iron metal and is referred to the presence of iron carbide and gas phase in this catalytic reaction. With a series of complicated mechanisms, methane is produced on the surface of catalyst and in the gas phase as well, this would be elaborated by following paragraphs, thus we can conclude that surface tension of catalyst has less effect on these reactions.

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Parvulescu, Vasile I., and Simona M. Coman. "Core-Magnetic Composites Catalysts for the Valorization and Up-grading of the Renewable Feedstocks: A Minireview." Current Catalysis 8, no. 1 (June 21, 2019): 2–19. http://dx.doi.org/10.2174/2211544708666181227152000.

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Background: Core-magnetic composites offer unique possibilities to accommodate adequate amounts of acid-base and redox functional sites and hence to catalyze the biomass conversion reactions in a one-pot way. Moreover, due to the dual functionality, the core-magnetic composites provide a bridge between homogeneous and heterogeneous catalysis. Hence, this minireview aims to offer a comprehensive account of remarkable recent applications of core-magnetic composites in the catalytic processes for biomass valorization. Methods: A critical evaluation of synthetic methodologies utilized for the production of the magnetic nanoparticles, characterization techniques and catalytic applications is provided. Results: The benefits of their utilization are exemplified by most representative examples of one-pot transformation of cellulose and upgrading processes. Other recent examples constitute the lignin fragmentation on magnetic iron oxide-based catalysts and the renewable crude glycerol up-grading using core-shell magnetic iron oxide bio-based materials. Conclusion: The review provides important information on the distinctive properties of the functionalized core-magnetic composites. Moreover, this review offers useful information affording a largescale production development, in terms of catalyst and reaction conditions, tailoring selectivity, and the potential to regenerate the catalysts.

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Dasgupta, Natun, Milind Ajith Nayak, and Mario Gauthier. "Starch-Stabilized Iron Oxide Nanoparticles for the Photocatalytic Degradation of Methylene Blue." Polysaccharides 3, no. 3 (September 19, 2022): 655–70. http://dx.doi.org/10.3390/polysaccharides3030038.

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The photocatalytic Fenton process, which produces a strong oxidant in the form of hydroxyl radicals, is a useful method to degrade organic contaminants in water. The Fenton reaction uses hydrogen peroxide and Fe2+ ions under relatively acidic conditions (typically pH 2–3) to maintain solubility of the iron catalyst but is troublesome due to the large volumes of decontaminated yet highly acidic water generated. Starch-stabilized iron (Fe2+/Fe3+) oxide nanoparticles were synthesized to serve as a colloidal catalyst system as the hydrophilic starch effectively prevents precipitation of the nanoparticles under conditions closer to neutrality. To evaluate the usefulness of this catalyst system for the photo-Fenton degradation of methylene blue as a model dye, the preparation protocol used and the iron loading in the starch were varied. The photocatalytic Fenton reaction was investigated at pH values up to 4. Not only were the starch-stabilized catalysts able to decolorize the dye but also to mineralize it in part, that is, to degrade it to carbon dioxide and water. The catalysts could be reused in several degradation cycles. This demonstrates that starch is an efficient stabilizer for iron oxide nanoparticles in aqueous media, enabling their use as environmentally friendly and cost-effective photo-Fenton catalysts. These starch-stabilized iron nanoparticles may also be useful to degrade other dyes and pollutants in water, such as pesticides.

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Journal articles on the topic 'Iron catalysi'

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