Artículos (Química Inorgánica)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10919

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Low-coordinate bis-phosphine and monophosphine Ni(0) complexes: synthesis and reactivity in C–S cross-coupling
(Royal Society of Chemistry, 2025-01-03) Martín García, María Trinidad; Carrasco Carrasco, Carlos Jesús; Santamaría Gallardo, Nazaret; Maya Díaz, Celia María; Prieto Cárdenas, María Auxiliadora; Galindo del Pozo, Agustín; Nicasio Jaramillo, María del Carmen; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE)
Preformed Ni(0) complexes are rarely used as precatalysts in cross-coupling reactions, although they can incorporate catalytically active nickel directly into the reaction. In this work, we focus on the preparation and the catalytic application of low-coordinate Ni(0) complexes supported by bulky monophosphine ligands in C–S cross-coupling reactions. We have prepared two families of Ni(0) complexes, bis-phosphine aducts of the type [Ni(PR2Ar′)2] (Ar′ = m-terphenyl group) and monophosphine derivatives of the type [Ni(PR2Ar′)(DVDS)] (DVDS = divinyltetramethyldisiloxane). DFT calculations were used to account for the atypical bent structures displayed by the bis-phosphine Ni(0) complexes. Monophosphine-Ni(0) complexes display catalytic activity superior to bis-phosphine Ni(0) adducts, which suggests that the former facilitate the generation of highly reactive monoligated PNi(0) species. Furthermore, the reactivity of monophosphine-Ni(0) precatalysts outperform that observed with Ni(II) precatalysts with the same phosphine ligands, supporting a more facile activation step to the same catalytic species. This enhanced reactivity allows for the use of lower catalyst loadings (1–5 mol%) and for carrying out the challenging coupling between aryl chlorides and alkylthiols.
Synthesis, Characterization, and Preliminary In Vitro Anticancer Activity of Zinc Complexes Containing Amino Acid-Derived Imidazolium-Based Dicarboxylate Ligands
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-03-30) Carrasco Carrasco, Carlos Jesús; Pastor Navarro, Antonio; Conejo Argandoña, María del Mar; Álvarez González, Eleuterio; Calderón Montaño, José Manuel; López Lázaro, Miguel; Galindo del Pozo, Agustín; Universidad de Sevilla. Departamento de Química Inorgánica; Universidad de Sevilla. Departamento de Farmacología; Ministerio de Ciencia e Innovación (MICIN). España
Coordination polymers containing zinc and imidazolium-based dicarboxylate ligands, [LR]−, were synthesized by reacting zinc acetate with HLR compounds, 1. The resulting complexes were characterized and structurally identified using single-crystal X-ray diffraction, revealing polymeric structures for the complexes [Zn(LR)2]n (R = Gly, 2a; βAla, 2b) and [Zn(LLeu)2(H2O)2]n (2c). In these structures, the [LR]− ligands adopt a bridging monodentate μ-κ1-O1,κ1-O3 coordination mode, resulting in distorted tetrahedral (2a, 2b) or octahedral (2c) geometries around the zinc center. When the synthesis was carried out in the presence of amino acids, mixed ligand complexes [Zn(LR)(aa)(H2O)]n (R = aa = Val, 2d, and R = aa = Ile, 2e) were formed. Complexes 2d–2e were also structurally characterized using single-crystal X-ray crystallography, revealing that the ligand [LR]− maintained the same coordination mode, while the zinc center adopted a five-coordinated geometry. The cytotoxic activity of complexes 2a–2e was evaluated against three cancer cell lines and one non-cancerous cell line. Remarkably, these complexes exhibited higher toxicity against cancer cells than against the non-cancerous cell line, and they showed greater selectivity than carboplatin, a commonly used chemotherapy drug. Although, in general, these complexes did not surpass the selectivity of gemcitabine, complex 2c stood out for exhibiting a selectivity index value similar to that of gemcitabine against melanoma cells. Among the series, compounds 2a–2c demonstrated the highest activity, with 2a being the only complex with some selective activity against lung cancer. Complex 2b was the most active, though with low selectivity, while complex 2c exhibited the highest selectivity for melanoma and bladder cancer (selectivity index of 3.0).
Design of catalysts for selective CO2 hydrogenation
(Springer Nature, 2025-02-27) Ye, Runping; Ding, Jie; Ramírez Reina, Tomás; Duyar, Melis Seher; Li, Haitao; Luo, Wenhao; Zhang, Rongbin; Fan, Maohong; Feng, Gang; Sun, Jian; Liu, Jian; Universidad de Sevilla. Departamento de Química Inorgánica; Natural Science Foundation of Jiangxi Province; National Natural Science Foundation of China; National Key Research and Development Program of China
CO2 hydrogenation with green hydrogen is a practical approach for the reduction of CO2 emissions and the generation of high-value-added chemicals. Generally, product selectivity is affected by the associated reaction mechanisms, internal catalyst identity and structure, and external reaction conditions. Here we examine typical CO2 hydrogenation reaction pathways, which can provide insight useful for the atomic-level design of catalysts. We discuss how catalyst chemical states, particle sizes, crystal facets, synergistic effects and unique structures can tune product selectivity. Different catalysts, such as Fe-, Co-, Ni-, Cu-, Ru-, Rh-, Pd-based and bifunctional structured catalysts, and their influence on CO2 hydrogenation products (such as CO, methane, methanol, ethanol and light olefins) are discussed. Beyond catalyst design, emerging catalytic reaction engineering methods for assisting the tuning of product selectivity are also discussed. Future challenges and perspectives in this field are explored to inspire the design of next-generation selective CO2 hydrogenation processes to facilitate the transition towards carbon neutrality. (Figure presented.)
Size-tailored Ru nanoparticles deposited over γ-Al 2 O 3 for the CO 2 methanation reaction
(Elsevier, 2019-07-31) Navarro Jaén, Sara; Navarro de Miguel, Juan Carlos; Bobadilla Baladrón, Luis Francisco; Centeno Gallego, Miguel Ángel; Laguna Espitia, Óscar Hernando; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Economía y Competitividad (MINECO). España
By means of the polyol method, a series of 5 wt% Ru/Al 2 O 3 catalysts was synthesized controlling the particle size of the ruthenium species. The physico-chemical characterization demonstrated the successful particle size control of the Ru species, in such a way that higher the Ru/PVP ratio, higher the Ru particle size. Moreover, there are evidences that suggest preferential growth of the RuO 2 clusters depending on the Ru/PVP ratio. Regarding the catalytic activity during the CO 2 methanation, the total conversion and the CH 4 yield increased with the particle size of Ru. Nevertheless, a considerable enhancement of the catalytic performance of the most active system was evidenced at 4 bar, demonstrating the improvement of the thermodynamics (superior total conversion) and kinetics (superior reaction rate) of the CO 2 methanation at pressures above the atmospheric one. Finally, the in situ DRIFTS study allowed to establish that CO 2 was dissociated to CO* and O* species on the metallic Ru particles, followed by the consecutive hydrogenation of CO* towards CHO*, CH 2 O*, CH 3 O*, and finally CH 4 molecules, which were further desorbed from the catalyst. Thus from the mechanistic point of view, a suitable particle size of the Ru nanoparticles along with the high-pressure effects results in the enhancement of the availability of hydrogen and consequently in the formation of CH x O species that enhance the cleavage of the C–O bond, which is the rate-determining step of the overall CO 2 methanation process.
Catalytic Atroposelective Synthesis of C−N Axially Chiral Aminophosphines via Dynamic Kinetic Resolution
(John Wiley and Sons, 2024) Rodríguez Franco, Carlos; Roldán Molina, E.; Aguirre Medina, A.; Fernández Fernández, Rosario Fátima; Hornillos, Valentín; Lassaletta, José M.; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; Universidad de Granada
A ruthenium-catalyzed reductive amination via asymmetric transfer hydrogenation (ATH) has been used to perform an efficient dynamic kinetic resolution (DKR) of N-aryl 2-formyl pyrroles decorated with a phosphine moiety positioned at the ortho’ position. The strategy relies on the labilization of the stereogenic axis in the substrate facilitated by a transient Lewis acid-base interaction (LABI) between the carbonyl carbon and the phosphorus center. The reaction features broad substrate scope of aliphatic amines and N-aryl pyrrole scaffolds, and proceeds under very mild conditions to afford P,N atropisomers in good to high yields and excellent enantioselectivities (up to 99 % ee) for both diphenyl and dicyclohexylphosphino derivatives.
Titania Modifications with Fluoride, Sulfate, and Platinum for Photochemical Reduction of Chromium (VI)
(Universidad de Antioquia, 2024) Murcia, J. J.; Hernández Laverde, M.S.; Correa Camargo, I. A.; Rojas Sarmiento, H. A.; Navío Santos, José Antonio; Hidalgo López, M. D.; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia, Tecnología e Innovación (MINCIENCIAS). Colombia; Universidad Pedagógica y Tecnológica de Colombia (UPTC); Ministerio de Ciencia e Innovación (MICIN). España
In this work, Titania was modified by sulfation or fluorination and platinum on the surface to improve the Cr (VI) reduction efficiency compared to the bare TiO2 material synthesized by the sol-gel method. The synthesized materials were characterized by XRD, SBET, UV-Vis DRS, XRF, TEM, FTIR, and XPS. The modifications led to higher stability in the Anatase phase and surface area of this semiconductor. The addition of F and Pt in TiO2 led to absorption increases in the visible region of the electromagnetic spectrum. A correlation between the new physicochemical properties obtained after TiO2 modification and the photocatalytic performance of this material was observed. The best result in chromium reduction was obtained using Pt-S-TiO2 as the photocatalyst; this material showed a suitable combination of surface area, high UV-Vis absorption, high hydroxylation, and the existence of Pt nanoparticles on the surface, which favors an increased electron-hole pair half-life. Different reaction parameters were also evaluated, which demonstrated that the best photocatalytic performance was obtained under an N2 atmosphere, a light intensity of 120 W/m2, and 2 hours of total reaction time. Likewise, it was noted that an increase in reaction time from 2 to 5 hours, had a detrimental effect on reducing Cr (VI) efficiency.
Stability and Performance of BTC-based MOFs for Environmental Applications
(Elsevier, 2024) Rodríguez Esteban, Corina; Ayala Espinar, Regla; López Cartes, Carlos; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía
Two series of open metal site MOFs, HKUST-1 and MIL-100(Fe), have been successfully prepared using different methods of synthesis. Their features depend on the synthetic route as well as their role play in different environmental applications. The stability and performance of these BTC-based MOFs have been tested bearing in mind Congo Red (CR) removal, humidity adsorption and iodine capture and release. HKUST-1 and MIL-100(Fe) samples could offer a remarkable role in the adsorption of CR from aqueous solutions. However, the lability of HKUST-1 in water is revealed as a drawback for its reutilization in both static and agitation conditions. The former contrasts to the stability under ambient moisture. MIL-100(Fe) shows promising properties in both CR adsorption in aqueous solutions and humidity adsorption. Nonetheless, the performance largely depends on the synthesis conditions. Although CR removal is based on surface interaction, there is a relation between the adsorpted quantity and the specific surface area. The size and nature of iodine allows the diffusion in the pores of both HKUST-1 and MIL-100(Fe) MOFs. This way, the uptake of iodine is driving by the porosity and surface area of samples rather than their inherent nature. As a rule, the results of this work indicate that not only is it important the specific nature of the MOF chosen for a given application but also the way in which it has been synthesized and the conditions in which they are used. MIL-100(Fe)-R is revealed as the best suitable candidate to be used as a sorbent for CR in aqueous solutions, moisture and I2 gas.
Redefining the Symphony of Light Aromatic Synthesis Beyond Fossil Fuels: A Journey Navigating through a Fe-Based/HZSM-5 Tandem Route for Syngas Conversion
(American Chemical Society, 2024) Nawaz, Muhammad Asif; Blay Roger, José Rubén; Saif, Maria; Meng, F. H.; Bobadilla Baladrón, Luis Francisco; Ramírez Reina, Tomás; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España
The escalating concerns about traditional reliance on fossil fuels and environmental issues associated with their exploitation have spurred efforts to explore eco-friendly alternative processes. Since then, in an era where the imperative for renewable practices is paramount, the aromatic synthesis industry has embarked on a journey to diversify its feedstock portfolio, offering a transformative pathway toward carbon neutrality stewardship. This Review delves into the dynamic landscape of aromatic synthesis, elucidating the pivotal role of renewable resources through syngas/CO2 utilization in reshaping the industry’s net-zero carbon narrative. Through a meticulous examination of recent advancements, the current Review navigates the trajectory toward admissible aromatics production, highlighting the emergence of Fischer-Tropsch tandem catalysis as a game-changing approach. Scrutinizing the meliorated interplay of Fe-based catalysts and HZSM-5 molecular sieves would uncover the revolutionary potential of rationale design and optimization of integrated catalytic systems in driving the conversion of syngas/CO2 into aromatic hydrocarbons (especially BTX). In essence, the current Review would illuminate the path toward cutting-edge research through in-depth analysis of the transformative power of tandem catalysis and its capacity to propel carbon neutrality goals by unraveling the complexities of renewable aromatic synthesis and paving the way for a carbon-neutral and resilient tomorrow.
Reactive Surface Explored by NAP-XPS: Why Ionic Conductors Are Promoters for Water Gas Shift Reaction
(American Chemical Society, 2024) García Moncada, Nuria; Penkova, Anna Dimitrova; González Castaño, Míriam; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España
Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) experiments have been carried out in N2 and N2-H2O atmospheres on a Pt-based catalyst physically mixed with an Eu-doped ZrO2 ionic conductor as a function of temperature under realistic conditions of the water gas shift (WGS) reaction. This work aims to demonstrate the significant effect of having active H2O on the ionic conductor surface at reaction temperatures to provide it to Pt metal sites. The ionic conductor, Eu-doped zirconia matrix, presents defects (oxygen vacancies, Ov) that allows upon H2O dissociation the formation of a hydrogen-bonded molecular water layer favoring diffusion through a Grotthuss mechanism below 300 °C. In the presence of H2O, the Ov are occupied by hydroxyl species as observed in the Eu 4d spectra, which differentiate two types of Eu oxidation states. The Eu3+-to-Eu2+ atomic ratio increases with the occupancy of the Ov by hydroxyls. Moreover, while the Pt-based catalyst alone is unable to create Pt-OH bonds, the physical mixture of the Pt-based catalyst and the ionic conductor allows the formation of Pt-OH bonds from room temperature up to 300 °C. These data demonstrate that the increase in molecular water concentration on the ionic conductor surface up to 300 °C acts as a reservoir to provide water to the Pt surface, enhancing the catalyst performance in the WGS reaction, supporting the importance of the surface H2O concentration in the reaction kinetics.
Pressureless Sintering Kinetics Analysis of Ti3SiC2 and Ti2AlC Powdered MAX Phases
(Springer Nature, 2024) Córdoba Gallego, José Manuel; Universidad de Sevilla. Departamento de Química Inorgánica
This paper reports the pressureless sintering behavior and the activation energy of the powdered MAX phases Ti3SiC2 and Ti2AlC. A non-isothermal technique was used to determine the sintering kinetic parameter. The Ti3SiC2 and Ti2AlC MAX phases showed the maximum sintering rate at 1723 K, 0.14 and 0.10 µm/s, respectively. The sintering rate of the sample at different temperatures followed a cubic equation which was determined. The sintering activation energy (Ea) for the Ti3SiC2 and Ti2AlC samples was 362.1 kJ/mol and 640.3 kJ/mol, respectively.
Mechanochemistry for Organic and Inorganic Synthesis
(American Chemical Society, 2024) Reynes, Javier F.; León García, Félix; García, Felipe; Universidad de Sevilla. Departamento de Química Inorgánica; Agencia Estatal de Investigación. España; Fundación para el Fomento en Asturias de la Investigación Científica Aplicada y la Tecnología (FICYT); The Marie Skłodowska-Curie Actions (MSCA)
In recent years, mechanochemistry has become an innovative and sustainable alternative to traditional solvent-based synthesis. Mechanochemistry rapidly expanded across a wide range of chemistry fields, including diverse organic compounds and active pharmaceutical ingredients, coordination compounds, organometallic complexes, main group frameworks, and technologically relevant materials. This Review aims to highlight recent advancements and accomplishments in mechanochemistry, underscoring its potential as a viable and eco-friendly alternative to conventional solution-based methods in the field of synthetic chemistry.
Cooperative interaction between metallosurfactants, derived from the [Ru(2,2 '-bpy)(3)](2+) complex, and DNA
(Elsevier, 2015) Lebrón Romero, José Antonio; Ostos Marcos, Francisco José; Moyá Morán, María Luisa; López López, M.; Carrasco Carrasco, Carlos Jesús; López-Cornejo, María del Pilar; Universidad de Sevilla. Departamento de Química Física; Universidad de Sevilla. Departamento de Química Inorgánica; Junta de Andalucía; European Union (UE)
With the idea of improving and advancing the design and preparation of new reagents based on cationic surfactants for gene therapy, two luminescent metallosurfactants derived from the [Ru(2,2′-bpy)3]2+ complex were synthesized. Their interaction with DNA and the effect they exert on the conformation of the polynucleotide were studied by using different techniques. The equilibrium binding constants, Kb, of the two surfactants to DNA were obtained at different molar ratios X = [surfactant]/[DNA]. The observed sigmoidal dependence of Kb on X confirms the cooperative character of the binding. After the addition of a determined surfactant concentration, the condensation of the polymer was observed. The amount of surfactant needed to produce this conformational change is lower for the double stranded surfactant than for the single chain surfactant due to a stronger hydrophobic interaction. The addition of α-cyclodextrin molecules to the metallosurfactant/DNA solutions results in polynucleotide decompaction, which confirms the importance of the hydrophobic interactions in the condensation of the polynucleotide. Results also show the importance of choosing both a proper system to study and the most seeming measuring technique to use. It is demonstrated that, in some cases, the use of several techniques is desirable to obtain reliable and accurate results.
Induced-aggregates in Photocatalysis: An Unexplored Approach to Reduce the Noble Metal co-catalyst Content
(Elsevier, 2024) Bu, E. Q.; Chen, X. W.; López Cartes, Carlos; Monzón, A.; Delgado, J. J.; Ministerio de Economia, Industria y Competitividad (MINECO). España; Universidad de Cádiz
Photocatalysis has emerged as a promising and environmentally sustainable solution to produce high-purity hydrogen through ethanol photoreforming. It is commonly accepted that adding co-catalysts, especially noble metals, significantly enhances the catalytic activity of semiconductors. However, the high cost of noble metals such as Pt may limit the real application of this emerging technology. Here we evaluate the possibility of reducing the noble metal loading by creating the appropriate interface between pre-formed semiconductor nanoparticles. Commercial titania (P25) was selected as the semiconductor due to its commercial availability, facilitating the straightforward validation and corroboration of our results. Pt was selected as co-catalyst because one of the most efficient photocatalysts for the ethanol photo-reforming is still based on the use of P25 in combination with Pt. We report that the creation of induced aggregates dramatically improves the total hydrogen produced when very low loadings (≤0.05 wt%) of Pt are used. We have developed a pioneering reactor designed for conducting photoluminescence studies under authentic operational conditions of nanoparticle suspensions in the liquid phase. This approach allows us to obtain the average photoluminescence emission from the P25 agglomerates what it would be impossible to obtain by using standard solid samples holders. Thanks to this equipment, we can conclude that this remarkable improvement of the activity is mainly due to creation of an interface that favors the charge transfer between the particles of the aggregates. According to this, the titania nanoparticles of the agglomerates act as an antenna to collect the photons of the sun-light and produce the photo-excited electrons that will be transferred to the platinum nanoparticles located in the same agglomeration. In contrast, raw P25 with low loadings of Pt would have a high number of titania nanoparticles without platinum, and therefore, inactive. This result would be especially relevant in the case of immobilized photocatalytic systems for real future photocatalytic reactors because the immobilization of the semiconductors would generate similar interactions to the one created by our method. Consequently, the initial semiconductor immobilization followed by the subsequent photo-deposition of the co-catalyst emerges as a promising approach for a substantial reduction of the co-catalyst content.
Impact of the Biogas Impurities on the Quality of the Precipitated Calcium Carbonate in the Regenaration Stage of a Chemical Absorption Biogas Upgrading Unit
(Elsevier, 2024) Salinero González, Jesús; Gallego Fernández, Luz Marina; Portillo Estévez, Esmeralda; González Arias, Judith; Baena-Moreno, Francisco M.; Navarrete Rubia, Benito; Vilches Arenas, Luis Francisco; Universidad de Sevilla. Departamento de Química Inorgánica; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
Combining Carbon Capture and Storage (CCS) with producing competitive secondary raw materials is key to decarbonizing industry and reducing resource extraction. Biogas upgrading to biomethane stand out as an alternative, but a significant gap remains in integrating this process within a circular economy framework. This issue has been recently addressed by a process that integrates biogas upgrading via caustic absorption with the production of Precipitated Calcium Carbonate (PCC) and the recovery of sodium hydroxide from waste brine solution using membrane technologies. The profitability of this approach depends on the quality of the PCC, a critical factor that this work addresses. By characterizing PCC is determined whether trace compounds in biogas contaminate the PCC and potentially affect its commercial value. It also examines the CO2 absorption process and analyzes the aqueous samples from the filtration phase of the PCC slurry. Results confirm the high purity of PCC obtained from biogas treatment using Raman spectroscopy, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses show that the PCC is pure calcium carbonate, mainly in the stable calcite form, with a typical tetrahedral morphology and no detectable impurities. Characterization of aqueous solutions revealed organic trace compounds from biogas, with TOC concentrations of 9.7 (± 6.4) and 16.0 (± 8) mg C/l. Silicon measurements showed similar concentrations in the absorbent solution and filtrated PCC slurry. Additionally, ammonia escapes as gas, and hydrogen sulfide in the biogas likely contributed to sulfate salt formation. Analysis of the CO₂ absorption shows a first-order reaction with OH-, where the amount of CO₂ absorbed (46.3–50.0 g) closely matches the theoretical value of 48 g. The study reveals that most of the biogas impurities dissolve into the aqueous solution, being crucial for future studies and downstream membrane treatments, and the PCC is unaffected by these impurities with a purity suitable for commercial applications.
Finely Tunable Carbon Nanofiber Catalysts for the Efficient Production of HMF in Biphasic MIBK/H2O Systems
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Bounoukta, Charf Eddine; Megías Sayago, Cristina; Rendón Márquez, Nuria; Ammari, F.; Centeno, M. A.; Ivanova, Svetlana; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España
This work proposes catalytic systems for fructose dehydration to 5-hydroxymethylfurfural using a series of functionalized carbon nanofibers. The catalysts were synthesized via finely selected covalent grafting in order to include a variety of functionalities like pure Bronsted acid, tandem Brønsted/Lewis acid, and tandem Lewis acid/Lewis base catalysts. After the characterization and evaluation of acidity strength and the amount of acid centers, the catalyst series was screened and related to the product distribution. The best-performing catalyst was also used to optimize the reaction parameters in order to achieve 5-hydroxymethylfurfural yields rounding at 60% without significant humin formation.
Progress and Future Challenges in Designing High-Performance Ni/CeO2 Catalysts for CO2 Methanation: A Critical Review
(2025-01-20) Liu, Kun; Nawaz, Muhammad Asif; Liao, Guangfu; Universidad de Sevilla. Departamento de Química Inorgánica
The Ni/CeO2 catalyst stands out among various solid metal oxide catalysts for its exceptional catalytic proficiency, positioning it as a prime candidate for the industrialization of methanation processes. This review thoroughly examines the prevalent challenges associated with Ni/CeO2 in methanation reactions, compiles current strategies to overcome these hurdles, and presents novel perspectives. The review elucidates the structural characteristics of Ni/CeO2 and its applications in catalytic reactions, discusses various synthesis methods and their respective merits and demerits, explores catalytic reaction systems at both laboratory and industrial scales, and clarifies the underlying reaction mechanisms. Furthermore, it underscores the mainstream approaches to enhance the low-temperature activity of Ni/CeO2 in methanation and to mitigate activity decrement due to Ni agglomeration. The review concludes by proposing future directions for improving low-temperature methanation activity and preventing catalyst deactivation, encompassing the development of innovative catalyst architectures, integrating in-situ characterization with theoretical calculations, and investigating photothermal methanation catalytic systems. Undoubtedly, scientific researchers will persistently strive to develop Ni/CeO2 catalysts with high activity across a broad temperature range and robust stability, driving the industrialization of CO2 methanation technology in the foreseeable future.
Effect of Calcination Temperature on the Synthesis of Ni-based Cerium Zirconate for Dry Reforming of Methane
(Elsevier, 2024) Martín Espejo, Juan Luis; Merkouri, Loukia Pantzechroula; Odriozola Gordón, José Antonio; Ramírez Reina, Tomás; Pastor Pérez, Laura; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España
Dry reforming of methane (DRM) represents an alluring approach to the direct conversion of CO2 and CH4, gases with the highest global warming potential, into syngas, a value-added intermediate used in chemical industry. In this study, mixed oxide structures of cerium and zirconium doped with 10 wt% Ni were used due to the high thermal stability. This study showcased the importance of choosing suitable conditions and explored the impact of calcination temperature on Ce–Zr mixed oxides with Ni. XRD analysis confirmed the existence of different crystalline phases according to the calcination temperature. Redox characterisation showed a trade-off among calcination temperature, the dispersion of Ni clusters and its interaction with the support structure. Calcined catalysts at 900 and 1000 °C underwent harsh, long-term DRM conditions. Despite the low surface area of the designed catalysts, the stability experiments proved a relation between dispersion of Ni active phase and catalytic performance, showing an optimum calcination temperature of 1000 °C.
Integrating catalytic tandem reactions for the next generation of biofuels: A perspective
(Cell Press, 2024-08-15) Blay Roger, José Rubén; Carrasco Ruiz, Sergio; Ramírez Reina, Tomás; Bobadilla Baladrón, Luis Francisco; Odriozola Gordón, José Antonio; Nawaz, Muhammad Asif; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
In this piece, we explore the transformative potential of sustainable biofuel production as a solution to the energy crisis and a pivotal element in realizing the environmental and societal ambitions of Society 5.0. Through a critical examination of “bottom-up” and “top-down” strategies for converting bio-feedstocks sourced from anthropogenic activities into renewable fuels, the work underscores the need for innovation in catalysts and process intensification. By highlighting the advances and challenges in harnessing unconventional feedstocks and integrating renewable energy, this work points to a future where biofuels stand as a cornerstone of a sustainable energy landscape. The significance of this discussion extends beyond the technical realm, offering a vision for a circular economy that reduces dependence on fossil fuels, addresses climate change, and promotes global energy security. It calls for a united front among researchers, industry leaders, and policymakers to drive the biofuel sector toward efficiency, scalability, and widespread adoption.
Influence of the atmosphere on the formation of high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system via reactive flash sintering
(Elsevier, 2024-08-05) Manchón Gordon, Alejandro Fernando; Lobo-Llamas, C.; Molina Molina, Sandra; Perejón Pazo, Antonio; Sánchez-Jiménez, P. E.; Pérez-Maqueda, L. A.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Universidad de Sevilla. Departamento de Química Inorgánica; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
In this study, the feasibility of preparing quinary equimolar high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system was explored using the reactive flash sintering (RFS) technique. Various compositions were tested using this technique under atmosphere pressure, leading to the formation of two primary phases: rock-salt and spinel. Conversely, a new high-entropy oxide was produced as a single-phase material with the composition (Co0.2,Cu0.2,Mg0.2,Mn0.2,Ni0.2)O when RFS experiments were conducted in nitrogen atmosphere. The reducing conditions achieved in nitrogen enabled the incorporation of cations with oxidation states different from +2 into the rock-salt lattice, emphasizing the critical role of the processing atmosphere, whether inert or oxidizing, in the formation of high-entropy oxides. The electrical characterization of this material was obtained via impedance spectroscopy, exhibiting a homogeneous response attributed to electronic conduction with a temperature dependence characteristic of disordered systems.
Effect of Na/Ca Adsorbents on NiRu-DFM Performance for Integrated CO2 Capture and Hydrogenation
(2024-10-09) Gharamaleki, Soudabeh Bahrami; Carrasco Ruiz, Sergio; Penkova, Anna Dimitrova; Ramírez Reina, Tomás; Duyar, MeIis S.; Universidad de Sevilla. Departamento de Química Inorgánica
Integrated carbon dioxide capture and utilization (ICCU) technology is being developed to address the challenge of increasing atmospheric CO2 levels. Dual function materials (DFMs) are designed with catalytic and adsorbent components that enable the capture and utilization of CO2 within a single reactor. In this investigation, we systematically evaluated the performance of NiRu-DFMs incorporating oxides of Ca, Na, or a combination to identify effects on both activity and selectivity. Our findings underscore not only the role of adsorbent selection in dictating the overall performance of DFMs but also the pretreatment conditions (in situ reduction). Notably, the highest methanation activity is observed on an as-synthesized (oxidized) 10% Ca-DFM (223.21 μmol/gDFM) at 380 °C, surpassing all other as-synthesized or reduced DFMs. This study sheds light on the relationships between composition, pretreatment, temperature, and performance in DFMs, offering valuable insights into the advancement of new compositions for DFMs.

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