Iron-based Catalysts Research Articles

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

The production of light olefins, as the critical components in chemical industries, is possible via different technologies. The Fischer–Tropsch to olefin (FTO) process aims to convert syngas to light olefins with high selectivity over a proper catalyst, reduce methane formation, and avoid the production of excess CO2. This review describes the production of light olefins through the FTO process using both unsupported and supported iron-based catalysts. The catalytic properties and performances of both the promoted and bimetallic unsupported catalysts are reviewed. The effect of support and its physico-chemical properties on the catalyst activity are also described. The proper catalyst should have high stability to provide long-term performance without reducing the activity and selectivity towards the desired product. The good dispersion of active metals on the surface, proper porosity, optimized metal-support interaction, a high degree of reducibility, and providing a sufficient active phase for the reaction are important parameters affecting the reaction. The selection of the suitable catalyst with enhanced activity and the optimum process conditions can increase the possibility of the FTO reaction for light-olefins production. The production of light olefins via the FTO process over iron-based catalysts is a promising method, as iron is cheap, shows higher resistance to sulfur, and has a higher WGS activity which can be helpful for the feed gas with a low H2/CO ratio, and also has higher selectivity towards light olefins.

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

The preferential oxidation of CO (CO-PrOx) to CO2 is an effective catalytic process for purifying the H2 utilized in proton-exchange membrane fuel cells for power generation. Our current work reports on the synthesis, characterization and CO-PrOx performance evaluation of unsubstituted and magnesium-substituted iron- and cobalt-based oxide catalysts (i.e., Fe3O4, Co3O4, MgFe2O4 and MgCo2O4). More specifically, the ability of Mg to stabilize the MgFe2O4 and MgCo2O4 structures, as well as suppress CH4 formation during CO-PrOx was of great importance in this study. The cobalt-based oxide catalysts achieved higher CO2 yields than the iron-based oxide catalysts below 225 °C. The highest CO2 yield (100%) was achieved over Co3O4 between 150 and 175 °C, however, undesired CH4 formation was only observed over this catalyst due to the formation of bulk fcc and hcp Co0 between 200 and 250 °C. The presence of Mg in MgCo2O4 suppressed CH4 formation, with the catalyst only reducing to a CoO-type phase (possibly containing Mg). The iron-based oxide catalysts did not undergo bulk reduction and did not produce CH4 under reaction conditions. In conclusion, our study has demonstrated the beneficial effect of Mg in stabilizing the active iron- and cobalt-based oxide structures, and in suppressing CH4 formation during CO-PrOx.

Enhancement of Relatively Non-Toxic Dechlorination of Pcbs from Thermal Desorption Off-Gas Over Manganese-Doped Iron-Based Bimetallic Catalyst

Enhancement of Relatively Non-Toxic Dechlorination of Pcbs from Thermal Desorption Off-Gas Over Manganese-Doped Iron-Based Bimetallic Catalyst

Recyclable Cobalt-Doped Iron-Based Coordination Polymer Catalyst with Unique Shell-Shaped Agglomerate for Enhancing the Reaction Activity of Kumada-Coupling

Recyclable Cobalt-Doped Iron-Based Coordination Polymer Catalyst with Unique Shell-Shaped Agglomerate for Enhancing the Reaction Activity of Kumada-Coupling

PBA-derived high-efficiency iron-based catalysts for CO2 hydrogenation

The PBA-derived iron based catalyst effectively converts CO2 to hydrocarbons, especially C5+ hydrocarbons.

Effect of the Zr promoter on precipitated iron-based catalysts for high-temperature Fischer–Tropsch synthesis of light olefins

FeMnxZr and FeMnxZr2Na catalysts prepared by coprecipitation and impregnation methods were applied to investigate the promoting effects of Zr on iron-based catalysts for high-temperature Fischer–Tropsch synthesis (HTFT).

Effects of Indium Promoter on Iron-Based Catalysts for Co2 Hydrogenation to Hydrocarbons

Effects of Indium Promoter on Iron-Based Catalysts for Co2 Hydrogenation to Hydrocarbons

Carbon Supported Catalysts in Fischer-Tropsch Synthesis: Structural Properties of Carbon Supports

The structural properties of some carbon-based supports can prevent the formation of hot spots and improve catalyst stability at Fischer Tropsch Synthesis (FTS) temperature. Special attention and some examples are given to iron-based catalysts and their performance in FTS. The carbon supports’ structural properties such as metal-support interaction, effect of particle size, the confinement effect, graphitization degree of graphene, and interrelationship of catalyst properties, are linked to their function in FTS for supported catalysts. The modification effects of the catalysts with functional groups, promoters and heat treatment are related to FTS performance. The potential research areas and challenges posed by carbon support structural properties’ relationship to FTS performance are identified.

Role of Sio2 in Different Iron-Based Catalysts for Fischer-Tropsch Synthesis to Light Olefins

Role of Sio2 in Different Iron-Based Catalysts for Fischer-Tropsch Synthesis to Light Olefins

Silica-supported Fe/Fe\u2013O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives

The hydrogenation of nitriles to amines represents an important and frequently used industrial process due to the broad applicability of the resulting products in chemistry and life sciences. Despite the existing portfolio of catalysts reported for the hydrogenation of nitriles, the development of iron-based heterogeneous catalysts for this process is still a challenge. Here, we show that the impregnation and pyrolysis of iron(II) acetate on commercial silica produces a reusable Fe/Fe–O@SiO2 catalyst with a well-defined structure comprising the fayalite phase at the Si–Fe interface and α-Fe nanoparticles, covered by an ultrathin amorphous iron(III) oxide layer, growing from the silica matrix. These Fe/Fe–O core–shell nanoparticles, in the presence of catalytic amounts of aluminium additives, promote the hydrogenation of all kinds of nitriles, including structurally challenging and functionally diverse aromatic, heterocyclic, aliphatic and fatty nitriles, to produce primary amines under scalable and industrially viable conditions.

Evaluation of the aquathermolysis catalyst effect on the composition and properties of high-viscosity oil from the Strelovskoe field

The article examines the aquathermolysis process of high viscosity oil from Strelovskoe field developed by RITEK LLC using steam injection. Laboratory modeling of non-catalytic and catalytic aquathermolysis in a high-pressure reactor was performed. Laboratory tests have demonstrated the high efficiency of the iron-based oil-soluble catalyst developed at Kazan Federal University in the destruction reactions of resinous asphaltenes. Samples of the initial oil as well as products of non-catalytic and catalytic aquathermolysis in the presence of iron tallate and the solvent Asphalt-Resin-Paraffin Deposits were studied at temperatures of 200, 250 and 300°C for 24 hours. In addition, the gas composition of the oil aquathermolysis products and the viscosity-temperature characteristics of the oil samples were determined. The studies have shown that catalytic aquathermolysis has a significant effect on the changes in the composition and properties of oil from the Strelovskoe field. It was found that the presence of a catalyst contributes to decarboxylation reactions, increases the degree of desulfurization and decreases the viscosity of oil samples. Keywords: high-viscosity oil; aquathermolysis; catalyst precursor; steam thermal treatment; viscosity.

Understanding the roles of copper dopant and oxygen vacancy in promoting nitrogen oxides removal over iron-based catalyst surface: A collaborative experimental and first-principles study

In this work, we proposed a novel strategy of copper (Cu) doping to enhance the nitrogen oxides (NOx) removal efficiency of iron (Fe)-based catalysts at low temperature through a simple citric acid mixing method, which is critical for its practical application. The doping of Cu significantly improves the deNOx performance of Fe-based catalysts below 200 °C, and the optimal catalyst is (Cu0.22Fe1.78)1−δO3, which deNOx efficiency can reach 100% at 160–240 °C. From the macro aspects, the main reasons for the excellent catalytic activity of the (Cu0.22Fe1.78)1−δO3 catalyst are the large number of oxygen vacancies (Ovac), appropriate Fe3+ and Cu2+ contents, stronger surface acidity and redox ability. From the micro aspects, the Ovac plays a key role in enhancing molecular adsorption, oxidation, and the deNOx reaction over the Fe-based catalyst surface, which promoting order is CuOvac > Ovac > Cu. This work provides a new insight for the mechanism study of oxygen vacancy engineering and also accelerates the development of CuFe bimetal composite catalysts at low temperature.

Water Gas Shift Reaction Activity on Fe (110): A DFT Study

Metal Fe is one of the phases existing on iron-based catalysts for a high-temperature water gas shift reaction (WGSR), but research on the activity of metal Fe in WGSR is almost not reported. In this work, the density functional theory (DFT) method was used to systematically study the reaction activity and mechanisms of WGSR on metal Fe (110), including the dissociation of H2O, the transformation of CO and the formation of H2, as well as the analysis of surface electronic properties. The results show that (1) the direct dissociation of H2O occurs easily on Fe (110) and the energy barrier is less than 0.9 eV; (2) the generation of CO2 is difficult and its energy barrier is above 1.8 eV; (3) H migrates easily on the Fe surface and the formation of H2 also occurs with an energy barrier of 1.47 eV. Combined with the results of Fe3O4, it can be concluded that the active phase should be Fe3O4 with O vacancy defects, and the iron-rich region plays an important role in promoting the formation of H2 in WGSR.

Effect of Rb promoter on Fe3O4 microsphere catalyst for CO2 hydrogenation to light olefins

Alkali metals have been widely studied to improve the efficiency of CO2 hydrogenation to light olefins on iron-based catalysts. Herein, a series of Rb-promoted Fe3O4 microsphere catalysts were developed to understand the effects of Rb promoter on the catalytic performance. The 3wt%Rb/Fe3O4 catalyst showed high selectivity of light olefins (C2–C4, 47.4%) with a high olefin/paraffin ratio (10.7). XRD, H2-TPR, CO2-TPD, XPS analyses show that the proper Rb loading rate may adjust carbonaceous species content and ferric oxide content on the surface of the catalyst which is help for the synergistic effect to produce light olefins.

The catalytic hydrodesulfurization performance and mechanism of hierarchically porous iron-based catalyst for coal liquefaction oil

Hierarchically porous iron-based catalysts were prepared by impregnation and coprecipitation methods using carbon microsphere as a template. The catalytic hydrodesulfurization performance and mechanism of such catalysts for coal liquefaction oil were systematically characterized, especially by a gas chromatography atomic emission spectrometry (GC-AED). Results show that the as-prepared catalysts were highly dispersive nano-size particles (ca. 50 nm) with a large surface area (744.923 m2·g−1). During the catalyst preparation, the carbon template might lead to the aggregation of FexOy with different stoichiometries. Therefore, the hierarchically porous iron-based catalysts were with mixed-valence and vacancy as active sites. Particularly, catalysts prepared under nitrogen atmosphere were found with a certain nitrogen doping to form FeN and/or Fe-CN. It could offer more active sites and lower the CS bond strength, thus improve the desulphurization activity. In addition, the hierarchical pore structure could sufficiently adsorb hydrogen and sulfur-containing molecular to accelerate the mutual reaction among activated H radicals and S atoms. Consequently, the catalysts presented high efficiency and strong selectivity on the removal of sulfur heteroatom, even for the very stable thiophene and benzothiophene derivates. The conversion rates were achieved up to 100% and 74.23% for model compounds and coal liquefaction oil, respectively.

Comparison between Fe2O3/C and Fe3C/Fe2O3/Fe/C Electrocatalysts for N2 Reduction in an Alkaline Electrolyte.

Cost-effective and nonprecious iron-based catalysts were synthesized, evaluated, and compared for electrocatalytic N2 reduction reaction (NRR) under alkaline conditions in the potential range from -0.4 to 0.1 V [vs reversible hydrogen electrode (RHE)] at low temperature (≤60 °C) and atmospheric pressure. The tested H-type cell was separated by an anion exchange membrane in 6 M KOH alkaline electrolyte (pH = over 14) in order to minimize hydrogen evolution reaction and to directly form NH3 gas. The amount of ammonia synthesized was quantified using an indophenol blue method and cross-checked with 1H nuclear magnetic resonance spectroscopy and ion chromatography using both 14N2 and 15N2 gases. Because of the synergistic effect between the Fe3C, Fe2O3, and Fe composites in the NRR, both the ammonia formation rate and faradaic efficiency in Fe3C/Fe2O3/Fe/C were approximately fourfold higher than those in Fe2O3/C at 60 °C and 0.1 V (vs RHE). These results can provide insights into designing Fe-based electrocatalysts for NRR at atmospheric pressure.

Highly Dispersive Metal Atoms Anchored on Carbon Matrix Obtained by Direct Rapid Pyrolysis of Metal Complexes

Highly Dispersive Metal Atoms Anchored on Carbon Matrix Obtained by Direct Rapid Pyrolysis of Metal Complexes

Insights into enhanced peroxydisulfate activation with S doped Fe@C catalyst for the rapid degradation of organic pollutants

In this study, the S modified iron-based catalyst (S-Fe@C) for activating peroxydisulfate (PDS) was fabricated by heating the S-MIL-101 (Fe) precursor at 800 °C. The resulted S-Fe@C composite mainly consisted of carbon, Fe0, FeS, FeS2, and Fe3O4, and showed strong magnetism. Compared with Fe@C obtained from MIL-101 (Fe), the S-Fe@C exhibited much higher performance (1.5 times larger) on PDS activation and the S-Fe@C/PDS could rapidly degrade various organic pollutants in 5 min under the attack of the species of SO4-·, 1O2, electro-transfer and Fe(IV). The S element in enhancing the PDS activation mainly involved two mechanisms. Firstly, the doped S could speed up the electron transfer efficiency, resulting in a promotion on PDS decomposition; secondly, the S2- S22- or S0 could achieve the circulation of Fe2+ and Fe3+, leading to the formation of non-radicals Fe(IV) and 1O2.

Effects of Cobalt-Doped Modification on the Catalytic Reduction of SO2 with CO over an Iron/BFS Catalyst

To realize high-value sulfur recovery and decrease the reaction temperature, a cobalt-doped modified iron-based catalyst was prepared from blast furnace slag (BFS), which is a byproduct of steelmaking. The effects of the carrier and active components on the catalytic reduction performance were studied, and the mechanism of the optimized modification to promote catalytic reduction was explored. When the mass ratio of cobalt tetroxide, ferric oxide, and the carrier in the catalyst was 4:15:81, the temperature required for the reaction was reduced to 400 °C, and the SO2 conversion rate and average sulfur yield were maintained above 90 and 80% within 2 h, respectively. The results of an in situ diffuse reflectance infrared Fourier-transform spectroscopy experiment and density functional theory calculations revealed that the catalytic mechanism followed both the redox route and the cosine intermediate route. The cobalt-doped modification increased the intermediate acidic sites on the catalyst surface and widened the adsorption temperature range of the catalyst, thus positively promoting the catalytic reaction.

Towards Biomass Gasification Enhanced by Structured Iron-Based Catalysts

The main drawback for the development of biomass gasification technology is tar conversion. Among the various methods for tar abatement, the use of catalysts has been proposed in the literature. Most of the works reported in the literature on catalytic systems for biomass tar conversion refers to catalysts in the form of powder; however, deactivation occurs by fast clogging with particulates deriving from biomass gasification. The integration of catalytic filter element for particle and tar removal directly integrated into the freeboard of the reactor is a new concept recently proposed and patented. In this context, this paper evaluates the possibility to integrate a structured iron-based catalytic monolith in the freeboard of a fluidized bed gasifier to enhance biomass gasification. The effectiveness of using a monolith for gas conditioning has been preliminarily verified. The limited effect on the gas production and composition seems to be related to the limited range of operating conditions explored in this work rather than to the low activity of the iron-based catalyst. Further studies to optimize the performance and to assess the possible deactivation of the catalyst due to coke deposition must be carried out.