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Scientific Papers in SCI



2024


Química de Superficies y Catálisis

Influence of vanadium species on the catalytic oxidation of glucose for formic acid production

Álvarez-Hernández, D; Ivanova, S; Penkova, A; Centeno, MA
Catalysis Today, 441 (2024) 114906

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VOx/TiO2 catalysts with various theorical monolayer values have been prepared and used to study, for the first time, the effect of vanadium loading in the selective oxidation of glucose to formic acid. Monomeric or isolated vanadia species dominate at low loadings, evolving into polymeric chains at higher concentrations, while crystalline V2O5 is observed at loadings over the theoretical monolayer value. Their characterization by XRD, BET, ICP, DRIFTS, Raman, UV–vis, H2-TPR and NH3-TPD reveal distinct physicochemical characteristics influenced by the formed vanadia species, impacting sample acidity, reducibility, and catalytic activity. All catalysts exhibit significant activity, forming formic acid as the main product in the liquid phase and reaching a peak formic acid yield of 42 %. Post-reaction analysis reveals that the leaching-prone crystalline V2O5 compromises catalyst stability while isolated vanadia species demonstrate superior catalytic activity and leaching resistance. The findings of this study provide a strong basis for the development of a heterogeneous vanadia catalyst with improved interaction with the support.


November, 2024 | DOI: DOI10.1016/j.cattod.2024.114906

Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Application of novel Zn-MIL53(Fe) for removal of micropollutants using an activated peroxymonosulphate system

Terrón, D; Holgado, JP; Giráldez, A; Rosales, E; Sanromán, MA; Pazos, M
Journal of Environmental Chemical Engineering, 12

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Novel zinc-doped Metal-Organic Framework based on MIL53(Fe) (Zn-MIL53(Fe)) has been successfully synthesised in one-step, exhibiting dual applications as adsorbent and catalyst. Initially, the adsorption capacity of MIL53(Fe) and Zn-MIL53(Fe) for removing Rhodamine B was assessed through kinetic and isotherm studies. The bimetallic variant exhibited superior performance, showcasing enhanced adsorption capabilities, particularly in the context of its physical interaction under natural pH. After that, the catalytic activity of both synthesised materials was evaluated to generate sulphate radicals by activating PeroxyMonoSulphate (PMS). It was also demonstrated that Zn-MIL53(Fe) exhibited the best catalytic activity being optimised using response surface methodology for Rhodamine B degradation (0.11 mM PMS and 43.2 mg Zn-MIL53(Fe)). Under optimal conditions, favourable outcomes were attained, facilitating the degradation of Rhodamine B, Fluoxetine, and Sulfamethoxazole by 93, 99, and 75 %, respectively. Furthermore, the operational stability of the Zn-MIL53(Fe) was verified, as it remains structurally and catalytically intact after different cycles.


October, 2024 | DOI: 10.1016/j.jece.2024.113403

Química de Superficies y Catálisis

Electrochemical tailoring of graphite properties for tunable catalytic selectivity of glucose conversion to 5-hydroxymethylfurfural

Delgado, G; Bounoukta, CE; Ivanova, S; Centeno, MA; Villar-Rodil, S; Paredes, JI; Cazaña, F; Monzón, A; García-Dalí, S
Applied Surface Science, 671 (2024) 160677

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This study presents a novel approach for boosting the selectivity of 5-hydroxymethylfurfural (HMF) production from glucose through electrochemical modification of graphite materials. Three distinct graphitic substrates were subjected to controlled electrochemical treatments utilizing sodium sulfate or phosphoric acid as electrolytes. The process expanded the graphite particles/pieces and introduced oxygenated functional groups to the exposed surfaces while preserving the structural integrity of the bulk material. The resulting modifications influenced the type and quantity of Lewis and Brønsted acidic sites, providing exhaustive control over reaction pathways leading to HMF. This electrochemically modified graphite demonstrated superior tunability compared to traditional metal-based catalysts, enabling dynamic optimization of reaction conditions for enhanced HMF yield. The controlled introduction of functional groups facilitated the tailoring of active sites, significantly impacting the kinetics of glucose conversion and achieving HMF selectivity up to 95%. This level of precision in controlling catalytic properties is essential for maximizing HMF yield while minimizing undesired by-product formation, addressing a critical challenge in HMF production.


October, 2024 | DOI: 10.1016/j.apsusc.2024.160677

Nanotecnología en Superficies y Plasma

Nucleation and growth of plasma sputtered silver nanoparticles under acoustic wave activation

Reichel, H; García-Valenzuela, A; Espino-Román, JA; Gil-Rostra, J; Regodón, GF; Rico-Gavira, V; Borrás, A; Gómez-Ramírez, A; Palmero, A; González-Elipe, AR; Oliva-Ramírez, M
Applied Surface Science, 669 (2024) 160566

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Early results on the plasma deposition of dielectric thin films on acoustic wave (AW) activated substrates revealed a densification pattern arisen from the focusing of plasma ions and their impact on specific areas of the piezoelectric substrate. Herein, we extend this methodology to tailor the plasma deposition of metals onto AW-activated LiNbO3 piezoelectric substrates. Our investigation reveals the tracking of the initial stages of nanoparticle (NP) formation and growth during the submonolayer deposition of silver. We elucidate the specific role of AW activation in reducing particle size, enhancing particle circularity, and retarding NP agglomeration and account for the physical phenomena making these processes differ from those occurring on non-activated substrates. We provide a comparative analysis of the results obtained under two representative plasma conditions: diode DC sputtering and magnetron sputtering. In the latter case, the AW activation gives rise to a 2D pattern of domains with different amounts of silver and a distinct size and circularity for the silver NPs. This difference was attributed to the specific characteristics of the plasma sheath formed onto the substrate in each case. The possibilities of tuning the plasmon resonance absorption of silver NPs by AW activation of the sputtering deposition process are discussed.


October, 2024 | DOI: 10.1016/j.apsusc.2024.160566

Materiales y Procesos Catalíticos de Interés Ambiental y Energético

In situ XRD and operando XRD-XANES study of the regeneration of LaCo0.8Cu0.2O3 perovskite for preferential oxidation of CO

Pereñiguez, RP; Ferri, D
Materials Today Sustainability, 27 (2024) 100867

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Combinations of perovskite-type oxides with transition and precious metals exhibit remarkable regenerating properties that can be exploited for catalytic applications. The objective of the present work was to study the structural changes experienced by LaCo0.8Cu0.2O3 under reducing/oxidizing atmosphere (redox) and Preferential Oxidation of CO (PrOx, with high H2 concentration) conditions and their reversibility. LaCo0.8Cu0.2O3 was prepared by ultrasonic spray combustion and was characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Structural changes were followed by operando XRD and XAS. Metallic Co and Cu were segregated under both sets of reducing conditions and re-dissolved into the perovskite upon oxidation at 500 °C. Simultaneously, the perovskite-type oxide disappeared under reducing conditions and formed again upon high-temperature oxidation. The effects of this reversible reduction/dissolution of B-site metals on catalyst structure and activity were studied concerning the catalytic process of PrOx. The active phases of cobalt and copper oxides suffer a reduction during the PrOx reaction due to the high H2 concentration; thus, the application of an intermediate oxidation treatment can regenerate the catalytic system and the perovskite can be used for several cycles of reaction and regeneration. In contrast, when this intermediate oxidation treatment is not applied, the catalytic performance decreases in successive activity cycles.


September, 2024 | DOI: 10.1016/j.mtsust.2024.100867

 

 

 

 

 

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