Menú secundario

Artículos SCI



2022


Materiales Coloidales

Outstanding MRI contrast with dysprosium phosphate nanoparticles of tuneable size

Gómez-González, E.; Caro, C.; García-Martín, ML; Becerro, AI; Ocaña, M.
Nanoscale, 14 (2022) 11461-11470

Show abstract ▽

The use of high-field magnets for magnetic resonance imaging (MRI) is expected to experience the fastest growth rate during the present decade. Although several CAs for MRI scanners using high magnetic fields have been reported, they are mostly based on fluoride matrices, which are known for their low chemical stability in aqueous suspensions. Chemically stable MRI CAs for high-field magnets are therefore needed to enable the advances in MRI technique. Herein, we synthesized uniform DyPO4 nanoparticles (NPs) with tuneable sizes between 23 and 57 nm using homogeneous precipitation in butanol. The NPs were successfully functionalized with polyacrylic acid (PAA) and showed good colloidal stability in aqueous suspensions. Chemical stability was also assessed in PBS, showing negligible solubility. The effect of particle size on the transversal relaxivity value (r(2)) was further explored at 9.4 T, finding a clear increase in r(2) with particle size. The r(2) value found for the largest NPs was 516 mM(-1) s(-1), which is, to the best of our knowledge, the highest r(2) value ever reported at 9.4 T for any Dy-based nanometric particles in the literature. Finally, the latter NPs were submitted to biosafety studies after polyethylene glycol (PEG) functionalization. Cell morphology, induction of necrotic/late apoptotic cells, and mitochondrial activity were thoroughly analyzed. The results clearly indicated negligible toxicity effects under the assayed conditions. Short- and long-term in vivo pharmacokinetics of the intravenously injected NPs were assessed by dynamic T-2-weighted MRI and quantitative T-2 mapping, revealing faster liver than spleen uptake, while no accumulation was observed in the kidneys. Finally, no histopathological changes were observed in any of the studied organs, including the liver, kidney, spleen, and lung, which provide further evidence of the biocompatibility of DyPO4 NPs and, therefore, their suitability as bioimaging probes.


Agosto, 2022 | DOI: 10.1039/d2nr02630a

Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Shepherding reaction intermediates to optimize H-2 yield using composite-doped TiO2-based photocatalysts

Barba-Nieto, I.; Colon, G; Fernández-García, M; Kubacka, A
Chemical Engineering Journal, 442 (2022) 136333

Show abstract ▽

Optimization of Pt-promoted TiO2-based is key to promote the photocatalytic production of hydrogen using sacrificial alcohol molecules. Combination of doping and surface decoration of the mentioned base photoactive material is here exploited to maximize hydrogen yield. Using the quantum efficiency parameter, it is shown that the resulting composite system can boost activity up to 7.3 times within the whole methanol:water mixture ratio, yielding quantum efficiencies in the ca. 13-16 % range. The key role of the different components in generating charge carrier species and their use to trigger the sacrificial molecule evolution and control reaction kinetics are examined through an in-situ spectroscopic study. The study unveils the complex reaction mechanism, with generation of C1 to C3 molecules from different carbon-containing radicals, and interprets the physical origin of the huge H2 production enhancement occurring in doped-composite titania-based catalysts.


Agosto, 2022 | DOI: 10.1016/j.cej.2022.136333

Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Tuning the co-catalyst loading for the optimization of thermo-photocatalytic hydrogen production over Cu/TiO2

Platero, F; Caballero, A; Colon, G
Applied Catalysis A-General, 643 (2022) 118804

Show abstract ▽

We have optimized the H-2 production by methanol thermo-photocatalytic reforming in the gas phase using Cu/TiO2 catalyst by tuning metal loading. Metal co-catalyst has been deposited by means of chemical reduction deposition. We have stated that thermo- and thermo-photocatalytic process leads to a notable H-2 production at 200 C. By in-situ FTIR studies we evidenced that formate formation follows a different evolution depending on the reforming experiment. These surface formate would lead to CO formation through dehydration reaction. At higher Cu content the low CO selectivity denote that water-gas-shift reaction would predominate and exalt H-2 yield. Thus, different optimum Cu content is found for each reforming experiment. While for the photocatalytic reforming Cu/TiO2 (2 wt%) is the best catalyst of the series, we should increase the Cu content to Cu/TiO2 (5 wt%) to achieve the optimum performance for thermo-photocatalytic reforming of methanol.


Agosto, 2022 | DOI: 10.1016/j.apcata.2022.118804

Química de Superficies y Catálisis

Catalytic Upgrading of Biomass-Gasification Mixtures Using Ni-Fe/ MgAl2O4 as a Bifunctional Catalyst

Tarifa, P; Reina, TR; González-Castaño, M; Arellano-Garcia, H
Energy & Fuels, 36 (2022) 8267-8273

Show abstract ▽

Biomass gasification streams typically contain a mixture of CO, H-2, CH4, and CO(2 )as the majority components and frequently require conditioning for downstream processes. Herein, we investigate the catalytic upgrading of surrogate biomass gasifiers through the generation of syngas. Seeking a bifunctional system capable of converting CO2 and CH4 to CO, a reverse water gas shift (RWGS) catalyst based on Fe/MgAl(2)O(4 )was decorated with an increasing content of Ni metal and evaluated for producing syngas using different feedstock compositions. This approach proved efficient for gas upgrading, and the incorporation of adequate Ni content increased the CO content by promoting the RWGS and dry reforming of methane (DRM) reactions. The larger CO productivity attained at high temperatures was intimately associated with the generation of FeNi3 alloys. Among the catalysts' series, Ni-rich catalysts favored the CO productivity in the presence of CH4, but important carbon deposition processes were noticed. On the contrary, 2Ni-Fe/MgAl2O4 resulted in a competitive and cost-effective system delivering large amounts of CO with almost no coke deposits. Overall, the incorporation of a suitable realistic application for valorization of variable composition of biomass-gasification derived mixtures obtaining a syngas-rich stream thus opens new routes for biosyngas production and upgrading.


Agosto, 2022 | DOI: 10.1021/acs.energyfuels.2c01452

Química de Superficies y Catálisis

Catalytic reforming of model biomass-derived producer gas

Azancot, L; Bobadilla, LF; Centeno, MA; Odriozola, JA
Fuel, 320 (2022) 123843

Show abstract ▽

This work includes a complete study of the reaction of reforming a simulated producer gas stream comparing a Ni-based catalyst with another one promoted with potassium to enhance the resistance to coke formation. Although coke deposition is unavoidable in the presence of tars in the stream, the analysis of different reaction parameters revealed that operating at 750 degrees C, weight hourly space velocity (WHSV) of 60 L-1 g(-1) h(-1) and 10-20 vol% of steam is possible to minimize the accumulation of carbon deposits. Moreover, it was demonstrated that the addition of potassium helps to mitigate carbon formation, but a high concentration of steam leads to nickel sintering and/or partial oxidation of metallic nickel. On this basis, it was successfully evidenced that the Ni-K catalyst is an excellent candidate for obtaining clean syngas from producer gas reforming.


Julio, 2022 | DOI: 10.1016/j.fuel.2022.123843

 

 

 

 

 

icms