Selective Carbon Dioxide Hydrogenation to Olefin-Rich Hydrocarbons by Cu/FeOx Nanoarchitectures Under Atmospheric Pressure

The conversion of carbon dioxide into fuels and fine chemicals is a highly desirable route for mitigating flue gas emissions. However, achieving selectivity toward olefins remains challenging and typically requires high temperatures and pressures. Herein, we address this challenge using 12 nm copper nanoparticles supported on FeOx micro-rods, which promote the selective hydrogenation of CO2 to light olefins (C2-C4) under atmospheric pressure. This catalyst achieves up to 27% conversion and 52% selectivity toward C2-C4 olefins, along with the production of C2-C4 paraffins, C5+ hydrocarbons (with all C1+ products totalling to up to about 75%), and methane, while suppressing CO formation to just 1% at 340 °C. The enhanced performance of the Cu/FeOx pre-catalyst is attributed to the efficient in situ generation of iron carbides (Fe5C2) in the presence of copper nanoparticles, as confirmed by ex situ XRD analysis. Copper facilitates the reduction of FeOx to form Fe5C2, a crucial intermediate for shifting the reaction equilibrium toward higher hydrocarbons. The hydrogenation of CO2 to higher hydrocarbons proceeds through the reverse water-gas shift reaction coupled with Fischer-Tropsch synthesis.

Single-Phase θ-Fe3C Derived from Prussian Blue and Its Catalytic Application in Fischer-Tropsch Synthesis

Elucidation of the intrinsic catalytic principle of iron carbides remains a substantial challenge in iron-catalyzed Fischer-Tropsch synthesis (FTS), due to possible interference from other Fe-containing species. Here, we propose a facile approach to synthesize single-phase θ-Fe3C via the pyrolysis of a molecularly defined Fe-C complex (Fe4[Fe(CN)6]3), thus affording close examination of its catalytic behavior during FTS. The crystal structure of prepared θ-Fe3C is unambiguously verified by combined XRD and MES measurement, demonstrating its single-phase nature. Strikingly, single-phase θ-Fe3C exhibited excellent selectivity to light olefins (77.8%) in the C2-C4 hydrocarbons with less than 10% CO2 formation in typical FTS conditions. This strategy further succeeds with promotion of Mn, evident for its wide-ranging compatibility for the promising industrial development of catalysts. This work offers a facile approach for oriented preparation of single-phase θ-Fe3C and provides an in-depth understanding of its intrinsic catalytic performance in FTS.

Preparation of Iron Carbides Formed by Iron Oxalate Carburization for Fischer–Tropsch Synthesis

Different iron carbides were synthesized from the iron oxalate precursor by varying the CO carburization temperature between 320 and 450 °C. These iron carbides were applied to the high-temperature Fischer–Tropsch synthesis (FTS) without in situ activation treatment directly. The iron oxalate as a precursor was prepared using a solid-state reaction treatment at room temperature. Pure Fe5C2 was formed at a carburization temperature of 320 C, whereas pure Fe3C was formed at 450 °C. Interestingly, at intermediate carburization temperatures (350–375 °C), these two phases coexisted at the same time although in different proportions, and 360 °C was the transition temperature at which the iron carbide phase transformed from the Fe5C2 phase to the Fe3C phase. The results showed that CO conversions and products selectivity were affected by both the iron carbide phases and the surface carbon layer. CO conversion was higher (75–96%) when Fe5C2 was the dominant iron carbide. The selectivity to C5+ products was higher when Fe3C was alone, while the light olefins selectivity was higher when the two components (Fe5C2 and Fe3C phases) co-existed, but the quantity of Fe3C was small.

Synthesis and structural characterization of CoxFe3−xC (0 ≤ x ≤ 0.3) magnetic nanoparticles for biomedical applications

The ferrofluids of pure and Co-substituted iron carbides exhibited heating abilities suitable for bioapplications.

Iron Carbides and Nitrides: Ancient Materials with Novel Prospects

Iron carbides and nitrides have aroused great interest in researchers, due to their excellent magnetic properties, good machinability and the particular catalytic activity. Based on these advantages, iron carbides and nitrides can be applied in various areas such as magnetic materials, biomedical, photo- and electrocatalysis. In contrast to their simple elemental composition, the synthesis of iron carbides and nitrides still has great challenges, particularly at the nanoscale, but it is usually beneficial to improve performance in corresponding applications. In this review, we introduce the investigations about iron carbides and nitrides, concerning their structure, synthesis strategy and various applications from magnetism to the catalysis. Furthermore, the future prospects are also discussed briefly.

Solution Growth of Modified Ultrathin W18 O49 Nanobelts with Enhanced Chemical Activity against Alkylamine Radicals

Group IVB ions (Ti⁴⁺ and Zr⁴⁺ ) are employed to modify solution growth of W₁₈ O₄₉ nanocrystals. In the presence of group IVB ions, the morphology of the produced monoclinic W₁₈ O₄₉ nanocrystals can be modulated from inhomogeneous shapes to uniform an ultrathin nanobelt with the (1‾ 01) lattice plane being the main exposure surface. Interestingly, the ultrathin W₁₈ O₄₉ nanobelts exhibit a unique chemical activity against alkylamine radicals, probably originated from the highly increased exposure of the (1‾ 01) plane with extra tungsten and oxygen atoms inserted in the regular lattice, which makes this nanomaterial an active photocatalyst for the N-de-ethylation reaction of the rhodamine B molecules, as well as a promising gas sensor matrix with selective responses to alkylamine molecules, including diethylamine, dimethylamine, triethylamine and trimethylamine. These results could provide useful inspiration for developing other functional nanomaterials with technical significance via modification of their morphologies and chemical properties.

Nitrogen-doped Fe3C@C particles as an efficient heterogeneous photo-assisted Fenton catalyst

The oxygen in Fe₃O₄ nanoparticles was replaced by carbon and nitrogen from the graphitic carbon nitride fragments released from dicyandiamide condensation.

Ca-doped CuS/graphene sheet nanocomposite as a highly catalytic counter electrode for improving quantum dot-sensitized solar cell performance

In this study, the highest energy conversion efficiency is obtained by Ca- CuS/GS CE, corresponding to efficiency increment (70%) compared to the CuS bare CE.

Size and morphology-controlled synthesis of Ni3C nanoparticles in a TEG solution and their magnetic properties

Nickel carbide nanoparticles (Ni₃C NPs) were synthesized by a polyol solution refluxing route at a temperature of 300 °C for 20 min using triphenylphosphine oxide (TPPO) as the surfactant.

(Fe1−xNix)3N nanoparticles: the structure, magnetic and photocatalytic properties for water splitting

Fe₃N and (Fe_1−xNi_x)₃N nanoparticles (NPs) were prepared via a simple sol–gel method.

Facile synthesis of mesoporous carbon nanocomposites from natural biomass for efficient dye adsorption and selective heavy metal removal

Mesoporous carbon nanocomposites, processed from natural cottonviacatalytic graphitization, show excellent organic dye adsorption and selective heavy metal removal from polluted water.