Iron Catalyst Research Articles

Unlocking Syngas Synthesis from the Catalytic Gasification of Lignocellulose Pinewood: Catalytic and Pressure Insights.

Modern technologies transform biomass into commodity chemicals, biofuels, and solid charcoal, making it appear as a renewable resource rather than organic waste. The effectiveness of Mo, Fe, Co, and Ni metal catalysts was investigated during the gasification of lignocellulosic pinewood. The primary goal was to compare the performance of iron and nickel catalysts in the low- and high-pressure production of syngas from pinewood. This is the first study that has reported high-pressure gasification of pinewood without the use of an external gasifying agent, producing syngas containing hydrogen, carbon monoxide, and carbon dioxide along with considerable amounts of methane with or without a catalyst. Also, the same gasification at low pressures was compared. In this study, the iron catalyst produces syngas more efficiently at higher pressure and 800 °C, and contains 43 mol % H2, 22 mol % CO2, 26 mol % CH4, and 8 mol % CO in comparison to the nickel catalyst. High pressure produces a large amount of methane too. The nickel catalyst produces higher syngas at low pressure and 850 °C, and contains 55 mol % H2, 9 mol % CO2, 5 mol % CH4, and 30 mol % CO. Low-pressure gasification produces less amounts of CH4 and CO2. Also, the H2/CO ratio is ∼1.81 using the nickel catalyst at low pressures, which is good for utilizing syngas as a feedstock. These results highlight the importance of catalyst selection, reactor configuration, and operating circumstances in adjusting gasification product composition. The study's findings provide information about optimizing syngas production from pinewood, which is critical for the development of sustainable and efficient energy conversion technologies.

Ozone-initiated degradation of 1,2-dichlorobenzene over ceria-supported manganese, nickel, vanadium and iron catalysts

Abstract Oxidative degradation of 1,2-dichlorobenzene using different loadings of metal (Mn, Ni, V, and Fe) supported on CeO2 was studied. All metal (Mn, Ni, V, and Fe) loaded CeO2 catalysts were synthesized using the method called wet impregnation and the as-synthesized catalyst materials were characterized using different analytical instruments such as FT-IR, SEM-EDX, XRD, BET, ICP-OES, and TEM methods. The oxidation reactions of 1,2-dichlorobenzene were studied by bubbling substrate (1,2-dichlorobenzene) with ozone (0.0794 mg/L) into a glass reactor via a porous bubbler of porosity 2 over a period of 24 h. A 2.5 % Fe/CeO2 catalyst was found to be the most active catalyst with a percentage conversion of 62 % within 24 h of ozonation. The oxidation products were identified using GC-MS and FT-IR spectroscopy was used to study the functional groups present in the ozonation product. The ozonation products that were identified are mucochloric acid and 3,4-dichloro-2,5-furandione. All the V loaded on CeO2 catalysts produced 100 % mucohloric acid at the end of ozonation (24 h).

Effects of surface groups on Fe/ZnO catalysts for CO2 hydrogenation to olefin

Control of product distribution over CO2-FTO is challenging due to the difficulty in governing the C–C coupling of CHx species. Surface modification to iron catalysts shows potential but its role remains indistinct. Fe/ZnO was used as a model catalyst to investigate the effects of the surface groups on its catalytic performance for CO2-FTO. On hydroxyl group modified Fe/ZnO by H2O2-treatment, at 1000 h–1, 300 °C, and 1 MPa, the CO2 conversion, and the C4+ linear α-olefin selectivity rose to 50.2 % and 48.1 %, respectively. Alkyl group modified Fe/ZnO by stearic acid treatment exhibited higher activity (48.4 %) and the C2=–C3= selectivity (31.0 %). Characterizations showed that decorating the hydroxyl group boosted the formation of Fe5C2 and CHx species, promoting the chain growth for long-chain olefin, whereas the alkyl group modification retarded the activity decline through stabilizing active FeCx phases and forming graphite carbon which was conducive to suppressing secondary hydrogenation.

Redox performance of trivalent iron iminodisuccinic acid in converting hydrogen sulfide to sulfur: A new complexed iron catalyst

A novel iron complex formed with tetrapotassium iminodisuccinate (IDSK4) was developed for catalytic conversion of hydrogen sulfide from industrial gases to monomeric sulfur, and a small-scale apparatus for the conversion of hydrogen sulfide in the laboratory was set up.The voltammetric curves of the system were generated with an electrochemical workstation, which indicated a quasireversible process. The catalytic capacity of the catalyst was saturated at 93.8% of the theoretical value for the trivalent iron complex.The open-circuit potential of the system was in the range −0.3 to −0.2 V, which provided full conversion of hydrogen sulfide, and after regeneration by air, it was restored to the initial potential.Full-cycle experiments showed that with increasing numbers of cycles, the open-circuit potential of the regenerated system was not fully restored to the initial value, thus requiring the design of a continuous absorption–regeneration system for industrial use. For safe treatment of hydrogen sulfide in industrial exhaust gases, a single-tower unit with absorption–regeneration cycles was used, and for safe treatment of hydrogen sulfide in combustible industrial gases, a double-tower unit with absorption–regeneration separation was used. The oxidation performance of the system was quickly monitored by measuring the open-circuit potential.

Congested C(sp3)-rich architectures enabled by iron-catalysed conjunctive alkylation.

Catalytic cross-coupling by transition metals has revolutionized the formation of C-C bonds in organic synthesis. However, the challenge of forming multiple alkyl-alkyl bonds in crowded environments remains largely unresolved. Here, we report the regioselective functionalization of olefins with sp3-hybridized organohalides and organozinc reagents using a simple (terpyridine)iron catalyst. Aliphatic groups of various sizes are successfully installed on either olefinic carbon, furnishing a diverse array of products with congested cores featuring C- or heteroatom-substituted stereocenters. The method enables access to valuable but synthetically challenging C(sp3)-rich molecules, including alicyclic compounds bearing multiple contiguous stereocenters through annulation cascades. Mechanistic and theoretical studies suggest a stepwise iron-mediated radical carbometallation pathway followed by outer-sphere C-C bond formation, which potentially opens the door to a broader scope of transformations and new chemical space.

Design of a new ZnO photocatalytic Fenton-like system for enhancing the removal of methylene blue at neutral pH

Although doping, nanostructuration, metallization, and binary/ternary oxide systems are widely used to improve the degradation kinetics in photocatalytic processes, rapid electron _ hole recombination remains one of its major limitations. On the other hand, homogeneous photo-Fenton-like processes suffer from the slow regeneration of Fe3+/Fe2+ catalysts and the formation of iron sludge at pH > 3. In this work, a new catalytic system is designed based on the coupling of nanostructured ZnO thin films photocatalysts with Fe3+/H2O2 (Fenton-Like) for the degradation of methylene blue (MB) molecules under UVA irradiation, at near-neutral pH (7.5). This coupled process promotes the formation of additional reactive oxygen species and reduces the formation of sludge by accelerating the regeneration of the iron catalysts in the medium. Furthermore, it exhibits a single kinetic regime of degradation with a rate constant of 0.0049 min−1 exceeding the sum of both individual processes and allowing therefore the removal of 94 % of MB after 480 min.

Attapulgite-supported sulfidated nano Zero-Valent Iron activated persulfate advanced oxidation technology for degradation of polyethylene microplastics: Optimal design, change of particle size and degradation mechanisms

Microplastics (MPs), as a novel pollutant, have raised concerns about their potentialtoxicity and the wide-ranging ecological risks they may pose. In this study, a novel attapulgate-supported sulfidized nanoscale zero-valent iron (S-nZVI@ATP) catalyst was prepared for the activation of persulfate. We investigated the degradation efficiency and mechanism of polyethylene microplastics (PE) using the S-nZVI@ATP activated persulfate advanced oxidation process. Various factors, such as temperature,pH, catalyst dosage, and persulfate concentration, were evaluated for their influence on the oxidative reaction in the system to determine the optimal degradation conditions. The average particle size of PE decreased from 64.2±0.86μm to 28.1±0.91μm after 24 hours of oxidative degradation. The reaction progressed, TOC in the solution showed an initial increase, followed by a decrease. Some PE was oxidized into small molecules substances such as alkanes, alkenes, ketones, alcohols, and carboxylic acids. S-nZVI@ATP continuously supplied Fe2+ for persulfate activation, generating strong oxidants SO4•-, •OH, and 1O2, among which SO4•- played a dominant role in oxidation system. The heterogeneous advanced oxidation system provided in this study offers an effective reference for PE degradation and holds great promise as a method for degrading MPs in water.

MXene-mediated reconfiguration induces robust nickel–iron catalysts for industrial-grade water oxidation

Nickel-iron oxy/hydroxides (NiFeOxHy) emerge as an attractive type of electrocatalysts for alkaline water oxidation reaction (WOR), but which encounter a huge challenge in stability, especially at industrial-grade large current density due to uncontrollable Fe leakage. Here, we tailor the Fe coordination by a MXene-mediated reconfiguration strategy for the resultant NiFeOxHy catalyst to alleviate Fe leakage and thus reinforce the WOR stability. The introduction of ultrafine MXene with surface dangling bonds in the electrochemical reconfiguration over Ni-Fe Prussian blue analogue induces the covalent hybridization of NiFeOxHy/MXene, which not only accelerates WOR kinetics but also improves Fe oxidation resistance against segregation. As a result, the NiFeOxHy coupled with MXene exhibits an extraordinary durability at ampere-level current density over 1,000 h for alkaline WOR with an ultralow overpotential of only 307 mV. This work provides a broad avenue and mechanistic insights for the development of nickel-iron catalysts toward industrial applications.

Iron-Catalyzed C(sp3)-C(sp3) Coupling to Construct Quaternary Carbon Centers.

The construction of quaternary carbon centers via C-C coupling protocols remains challenging. The coupling of tertiary C(sp3) with secondary or tertiary C(sp3) counterparts has been hindered by pronounced steric clashes and many side reactions. Herein, we have successfully developed a type of bisphosphine ligand iron complex-catalyzed coupling reactions of tertiary alkyl halides with secondary alkyl zinc reagents and efficiently realized the coupling reaction between tertiary C(sp3) and secondary C(sp3) with high selectivity for the initial instance, which provided an efficient method for the construction of quaternary carbon centers with high steric hindrance. The combination of an iron catalyst and directing group of the substrate makes the great challenging transformation possible.

Selective Oxidation of Hydrocarbons by Molecular Iron Catalysts Based on Molecular Recognition through π–π Interaction in Aqueous Medium

Selective Oxidation of Hydrocarbons by Molecular Iron Catalysts Based on Molecular Recognition through π–π Interaction in Aqueous Medium

Recent Advances in Solvent-free Organic Transformation via Iron-doped Nanocatalyst

Abstract: This article highlights current developments in iron-doped nanocatalyst-based solvent-free organic reactions. These catalysts have the potential to speed up processes under safe environmental settings and eliminate the need for hazardous organic solvents. Its application in a variety of fields is mostly due to its superparamagnetic nano diameters, which are affordable, easily separable, reusable, and eco-friendly. Thus, the present review article focuses on the compendious account of various doped iron nanocatalysts reported catalyzing organic transformation, including synthesis of bioactive compounds, condensation, multicomponent, annulation, esterification, coupling, alkylation, acylation reactions. The development of innovative, highly active, and reusable magnetic iron nanocomposite catalysts is crucial for the future of catalysis as it will pave the way for the creation of environmentally friendly and sustainable technology. The review will provide valuable insights for researchers who are designing new functionalized doped iron catalysts or utilizing these catalysts for various organic transformations that promote sustainable development. The development of new precursors and synthesis techniques, as well as recent improvements in the synthesis of these catalysts, are described. The article also emphasizes the significance of comprehending the underlying processes of these catalytic events, as well as the difficulties and possibilities for further study in this field. The potential of iron-doped nanocatalysts as an environmentally friendly and long-lasting method of organic synthesis is emphasized throughout this review.

Synergistic Electronic Interaction of Nitrogen Coordinated Fe-Sn Double-Atom Sites: An Efficient Electrocatalyst for Oxygen Reduction Reaction.

Double-atom site catalysts (DASs) have emerged as a recent trend in the oxygen reduction reaction (ORR), thereby modifying the intermediate adsorption energies and increasing the activity. However, the lack of an efficient dual atom site to improve activity and durability has limited these catalysts from widespread application. Herein, the nitrogen-coordinated iron and tin-based DASs (Fe-Sn-N/C) catalyst are synthesized for ORR. This catalyst has a high activity with ORR half-wave potentials (E1/2) of 0.92V in alkaline, which is higher than those of the state-of-the-art Pt/C (E1/2=0.83V), Fe-N/C (E1/2=0.83V), and Sn-N/C (E1/2=0.77V). Scanning electron transmission microscopy analysis confirmed the atomically distributed Fe and Sn sites on the N-doped carbon network. X-ray absorption spectroscopy analysis revealed the charge transfer between Fe and Sn. Both experimental and theoretical results indicate that the Sn with Fe-NC (Fe-Sn-N/C) induces charge redistribution, weakening the binding strength of oxygenated intermediates and leading to improved ORR activity. This study provides the synergistic effects of DASs catalysts and addresses the impacts of P-block elements on d-block transition metals in ORR.

Highly loaded bimetallic iron-cobalt catalysts for hydrogen release from ammonia

Ammonia is a storage molecule for hydrogen, which can be released by catalytic decomposition. Inexpensive iron catalysts suffer from a low activity due to a too strong iron-nitrogen binding energy compared to more active metals such as ruthenium. Here, we show that this limitation can be overcome by combining iron with cobalt resulting in a Fe-Co bimetallic catalyst. Theoretical calculations confirm a lower metal-nitrogen binding energy for the bimetallic catalyst resulting in higher activity. Operando spectroscopy reveals that the role of cobalt in the bimetallic catalyst is to suppress the bulk-nitridation of iron and to stabilize this active state. Such catalysts are obtained from Mg(Fe,Co)2O4 spinel pre-catalysts with variable Fe:Co ratios by facile co-precipitation, calcination and reduction. The resulting Fe-Co/MgO catalysts, characterized by an extraordinary high metal loading reaching 74 wt.%, combine the advantages of a ruthenium-like electronic structure with a bulk catalyst-like microstructure typical for base metal catalysts.

The Recent Advances in Iron-Catalyzed C(sp3 )-H Functionalization.

The use of iron as a core metal in catalysis has become a research topic of interest over the last few decades. The reasons are clear. Iron is the most abundant transition metal on Earth's crust and it is widely distributed across the world. It has been extracted and processed since the dawn of civilization. All these features render iron a noncontaminant, biocompatible, nontoxic, and inexpensive metal and therefore it constitutes the perfect candidate to replace noble metals (rhodium, palladium, platinum, iridium, etc.). Moreover, direct C-H functionalization is one of the most efficient strategies by which to introduce new functional groups into small organic molecules. The majority of organic compounds contain C(sp3 )-H bonds. Given the enormous importance of organic molecules in so many aspects of existence, the utilization and bioactivity of C(sp3 )-H bonds are of the utmost importance. This review sheds light on the substrate scope, selectivity, benefits, and limitations of iron catalysts for direct C(sp3 )-H bond activations. An overview of the use of iron catalysis in C(sp3 )-H activation protocols is summarized herein up to 2022.

Sustainable Aerobic Allylic C-H Bond Oxidation with Heterogeneous Iron Catalyst.

Emerging techniques are revolutionizing the realm of chemical synthesis by introducing new avenues for C-H bond functionalization, which have been exploited for the synthesis of pharmaceuticals, natural compounds, and functional materials. Allylic C-H bond oxidation of alkenes serves as possibly the most employed C-H bond functionalization reaction. However, sustainable and selective approaches remain scarce, and the majority of the existing conditions still hinge on hazardous oxidants or costly metal catalysts. In this context, we introduce a heterogeneous iron catalyst that addresses the above-mentioned concerns by showcasing the aerobic oxidation of steroids, terpenes, and simple olefins to the corresponding enone products. This novel method provides a powerful tool for the arsenal of allylic C-H bond oxidation while minimizing the environmental concerns.

Research Progress of Iron Catalysts with N,N,N‐tridentate Ligands for Ethylene Polymerization

AbstractSome iron complexes are found to be effective catalysts of ethylene polymerization and have become a research hotspot due to their advantages of high activity, good thermal stability, and mild reaction conditions. Compared with other systems, iron catalysts bearing N,N,N‐tridentate ligand have good comprehensive performance in catalyzing ethylene polymerization. This review article focuses on changes in the framework of bis(imino)pyridyl ligand and the effect of different substituents on the catalytic performance of ethylene polymerization (activity, molecular weight, thermal stability, etc.) since 2019. Despite significant achievements, many opportunities and possibilities are yet to be fully addressed, and a brief outlook on the future of issues should be focused on is provided.

Superefficient non-radical degradation of benzo[a]pyrene in soil by Fe-biochar composites activating persulfate

Efficient decomposition of organic pollutants in complex soil environments through non-radical pathways is vital but challenging. Herein, biochar supported nZVI (nZVI@BC800) fabricated by carbothermal reduction method was prepared for persulfate activation, exhibiting ultrafast degradation efficiency of benzo[a]pyrene of 71.80 % within 5 min with excellent adaptability to wide pH range of 3.0–9.0 and high anti-interference capacity to coexisting substances in soil. In nZVI@BC800/persulfate system, non-radical pathways including singlet oxygen (1O2) and electron transfer made dominant contributions to benzo[a]pyrene degradation. 1O2 could be produced not only by the reaction between C = O on BC800 and persulfate, but also via the transformation of O2∙- and ∙OH. On the other hand, biochar as an electron shuttle could accelerate electron transfer from benzo[a]pyrene to persulfate adsorbed on the catalyst. Additionally, possible degradation pathways of benzo[a]pyrene in nZVI@BC800/persulfate system were inferred through GC–MS and DFT calculations. Furthermore, the system could modulate the soil microbial community to further improve plant stress resistance. Therefore, this study provided a promising strategy via developing carbon-supported iron catalyst for carrying out persulfate-based non-radical pathways to remediate organic-polluted soil.

Hybrid O3/UV/Fe process using rebar flakes waste for removal of congo red dye in wastewater

In Indonesia, textile is one of the labour-intensive industries that makes an important contribution to the national economy sectors. This industry tends to develop rapidly to meet domestic and export needs. This phenomenon increases wastewater generation from the textile industry. Textile wastewater contains dyes that are designed to be durable to resist sunlight and washing process. These properties pose a challenge to the treatment of dye wastewater. The complex structure of dye molecules is generally difficult to degrade by conventional biological processes, while the physical-chemical precipitation process will generate hazardous sludge. Therefore, alternative treatment processes for dye removal are urgently required. In this work, ozonation (O3), ozone and ultraviolet (O3/UV), and catalytic ozone coupling with ultraviolet (O3/UV/Fe) processes were tested for decolourisation of synthetic Congo red dye wastewater. Laboratory assays were carried out under various operating conditions: pH (3-7); ozonation mode (continuous, sequential); and catalyst dose (0.5-2 g/L). Ozonation in sequential mode and the utilisation of rebar flake waste from building construction project as iron catalyst presents a degree of novelty in this work. Congo red decolourisation up to 97% was achieved in less than one-hour of reaction by the continuous O3 process. Mineralisation in terms of COD reduction (50%) can be increased by either performing ozonation in sequential mode (79%) and coupling with UV irradiation (86%). Nevertheless, the effect of the iron catalyst was found to be negligible.

Access to chiral β-amino sulfones from acrylamides and sulfur dioxide by iron catalysis

This method allows for the enantioselective synthesis of β-azide sulfones via iron-catalyzed vicinal azide-sulfonylation of acrylamides. It makes the first instance of achieving asymmetric construction through iron catalysis with SO2 insertion.

Recent progress in asymmetric radical reactions enabled by chiral iron catalysts.

Transition-metal-catalyzed radical asymmetric reactions offer a versatile and effective platform for accessing chiral organic molecules with high enantiopurity. Given that iron is the most abundant and less toxic transition metalic element available, the application of iron catalysts is considered to be a more sustainable and attractive approach. Over the last decade, several exciting and notable achievements have been witnessed. In this highlight, we aim to provide an overview of the progress in ligand-enabled iron-catalyzed asymmetric radical reactions, with an emphasis on the reaction mechanisms.