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155 results on '"Meledina, Maria"'

5. Multi Element ELNES Mapping of Compounds

Author

Jannis Daen, Gauquelin Nicolas, Meledina Maria, Zhao Yuchen, Chen Yunzhong, and Verbeeck Jo

Subjects
eels, elemental quantification, fine structure, Microbiology, QR1-502, Physiology, QP1-981, Zoology, QL1-991
Published
2024
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10. The role of hydrogen during Pt–Ga nanocatalyst formation

Author

Filez, Matthias, Redekop, Evgeniy A, Galvita, Vladimir V, Poelman, Hilde, Meledina, Maria, Turner, Stuart, Van Tendeloo, Gustaaf, Bell, Alexis T, and Marin, Guy B

Subjects
Inorganic Chemistry, Chemical Sciences, Affordable and Clean Energy, Physical Sciences, Engineering, Chemical Physics, Chemical sciences, Physical sciences
Abstract

Hydrogen plays an essential role during the in situ assembly of tailored catalytic materials, and serves as key ingredient in multifarious chemical reactions promoted by these catalysts. Despite intensive debate for several decades, the existence and nature of hydrogen-involved mechanisms - such as hydrogen-spillover, surface migration - have not been unambiguously proven and elucidated up to date. Here, Pt-Ga alloy formation is used as a probe reaction to study the behavior and atomic transport of H and Ga, starting from Pt nanoparticles on hydrotalcite-derived Mg(Ga)(Al)Ox supports. In situ XANES spectroscopy, time-resolved TAP kinetic experiments, HAADF-STEM imaging and EDX mapping are combined to probe Pt, Ga and H in a series of H2 reduction experiments up to 650 °C. Mg(Ga)(Al)Ox by itself dissociates hydrogen, but these dissociated hydrogen species do not induce significant reduction of Ga(3+) cations in the support. Only in the presence of Pt, partial reduction of Ga(3+) into Ga(δ+) is observed, suggesting that different reaction mechanisms dominate for Pt- and Mg(Ga)(Al)Ox-dissociated hydrogen species. This partial reduction of Ga(3+) is made possible by Pt-dissociated H species which spillover onto non-reducible Mg(Al)Ox or partially reducible Mg(Ga)(Al)Ox and undergo long-range transport over the support surface. Moderately mobile Ga(δ+)Ox migrates towards Pt clusters, where Ga(δ+) is only fully reduced to Ga(0) on condition of immediate stabilization inside Pt-Ga alloyed nanoparticles.

Published
2016

21. CO2 methanation with Ru@MIL-101 nanoparticles fixated on silica nanofibrous veils as stand-alone structured catalytic carrier

Author

UCL - SST/IMCN/MOST - Molecular Chemistry, Materials and Catalysis, Loccufier, Eva, Watson, Geert, Zhao, Yingrui, Meledina, Maria, Denis, Robbe, Derakhshandeh, Parviz Gohari, Van Der Voort, Pascal, Leus, Karen, Debecker, Damien P., De Buysser, Klaartje, De Clerck, Karen, UCL - SST/IMCN/MOST - Molecular Chemistry, Materials and Catalysis, Loccufier, Eva, Watson, Geert, Zhao, Yingrui, Meledina, Maria, Denis, Robbe, Derakhshandeh, Parviz Gohari, Van Der Voort, Pascal, Leus, Karen, Debecker, Damien P., De Buysser, Klaartje, and De Clerck, Karen

Abstract

An important challenge in the valorization of CO2 and H2 into fuels is the development of a stable, reusable and easy to handle heterogeneous catalyst. Here, a silica nanofibrous membrane is investigated as carrier for Ru nanoparticles, themselves encapsulated inside the metal organic framework (MOF) Cr-MIL-101. The catalytic membrane is investigated for the Sabatier methanation reaction. The direct electrospinning of a tetraorthosilicate (TEOS) sol results in a highly thermal resistant silica nanofibrous structure (up to 1100 °C) with pores between the fibers in the µm-range, allowing a high gas throughput with low pressure requirements. A straightforward dip-coating procedure of the carrier was used to obtain a Ru@MIL-101 functionalized silica nanofibrous veil, avoiding Ru clustering. The obtained catalytic membrane exhibited an apparent turnover frequency of 3257 h-1 at 250 °C. This system therefore paves the way towards structured reactors for efficient CO2 hydrogenation processes.

Published
2023

25. Inorganic Membranes Allow for a More Clever Use of Nanoparticles As CO2 Conversion Catalyst

Author

Loccufier, Eva, Watson, Geert, Zhao, Yingrui, Meledina, Maria, Van Der Voort, Pascal, Debecker, Damien, D'hooge, Dagmar, De Buysser, Klaartje, and De Clerck, Karen

Subjects
Technology and Engineering
Abstract

An important challenge in the valorization of CO2 and H2 into fuels is the development of a stable, reusable and easy to handle heterogeneous catalyst. Here, a silica nanofibrous membrane is investigated as carrier for Ru nanoparticles, themselves encapsulated inside the metal organic framework Cr-MIL-101. The catalytic membrane is investigated for the Sabatier methanation reaction. The direct electrospinning of a tetraorthosilicate sol-gel system results in a highly thermal resistant silica nanofibrous structure (up to 1100°C) with a large amount of pores between the fibers in the µm-range, allowing a high gas throughput with low pressure requirements. A straightforward dip-coating procedure of the carrier was used to obtain a Ru@MIL-101 functionalized silica nanofibrous veil, avoiding Ru clustering. The obtained catalytic membrane exhibited an apparent turnover frequency of 3257 h-1 at 250°C. This system therefore paves the way towards structured reactors for efficient CO2 hydrogenation processes.

Published
2022
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26. One-step synthesis of magnetic covalent organic framework composite for the adsorption of marine toxin okadaic acid.

Author

Romero, Vanesa, Fernandes, Soraia P. S., Gonçalves, Liliana P. L., Oliveira, Orlando, Meledina, Maria, Strutyński, Karol, Melle-Franco, Manuel, Kolen'ko, Yury V., Espiña, Begoña, and Salonen, Laura M.

Subjects
MARINE toxins, ARTIFICIAL seawater, DOMOIC acid, ADSORPTION (Chemistry), ADSORPTION capacity, MAGNETIC nanoparticles, RECYCLABLE material
Abstract

A one-step procedure is reported for the synthesis of a crystalline magnetic covalent organic framework (COF) composite. While pre-functionalization of the solid substrate with a building block prior to COF growth is typically required to obtain a crystalline COF composite, our approach uses a sub-stoichiometric amount of the diamino building block during the COF synthesis. This allows for the anchoring of the excess aldehyde on the dopamine-functionalized magnetic nanoparticles to promote COF growth, giving access to crystalline magnetic COF composite in only one step. No losses in crystallinity or surface area were observed as compared to bulk material. The COF composite was successfully applied for the removal of okadaic acid from synthetic seawater, where the composite material showed adsorption efficiency comparable to that found for the bulk COF. In addition, the material was recyclable during at least three consecutive cycles of adsorption/desorption using 2-propanol as desorption solvent, with merely minor losses in adsorption capacity. This work opens new avenues for synthesizing crystalline COF composites through shorter and easier routes, saving costs of sorbent preparation, and reinforces the great promise of COF composites for application in seawater biotoxin monitoring. [ABSTRACT FROM AUTHOR]

Published
2023
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27. Boron in Ni-Rich NCM811 Cathode Material: Impact on Atomic and Microscale Properties

Author

Roitzheim, Christoph, primary, Kuo, Liang-Yin, additional, Sohn, Yoo Jung, additional, Finsterbusch, Martin, additional, Möller, Sören, additional, Sebold, Doris, additional, Valencia, Helen, additional, Meledina, Maria, additional, Mayer, Joachim, additional, Breuer, Uwe, additional, Kaghazchi, Payam, additional, Guillon, Olivier, additional, and Fattakhova-Rohlfing, Dina, additional

Published
2021
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28. Elucidating the Influence of the d-Band Center on the Synthesis of Isobutanol

Author

Häusler, Johannes, Pasel, Joachim, Woltmann, Friederike, Everwand, Andreas, Meledina, Maria, Valencia, Helen, Lipińska-Chwałek, Marta, Mayer, Joachim, and Peters, Ralf

Subjects
d-band center, lcsh:Chemistry, heterogeneous catalysis, carbon neutral fuel, lcsh:QD1-999, ddc:540, lcsh:TP1-1185, Guerbet reaction, volcano curve, lcsh:Chemical technology, hydrogen borrowing, i-butanol
Abstract

Catalysts : open access journal 11(3), 406 (2021). doi:10.3390/catal11030406 special issue: "Special Issue "Engineering Materials for Catalysis" / Special Issue Editors: Prof. Dr. Albin Pintar, Guest Editor ; Prof. Dr. Nataša Novak Tušar, Guest Editor ; Prof. Dr. Günther Rupprechter, Guest Editor", Published by MDPI, Basel

Published
2021
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31. A Visible‐Light‐Harvesting Covalent Organic Framework Bearing Single Nickel Sites as a Highly Efficient Sulfur–Carbon Cross‐Coupling Dual Catalyst

Author

Chen, Hui, primary, Liu, Wanlu, additional, Laemont, Andreas, additional, Krishnaraj, Chidharth, additional, Feng, Xiao, additional, Rohman, Fadli, additional, Meledina, Maria, additional, Zhang, Qiqi, additional, Van Deun, Rik, additional, Leus, Karen, additional, and Van Der Voort, Pascal, additional

Published
2021
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33. A lanthanide-functionalized covalent triazine framework as a physiological molecular thermometer

Author

Gohari Derakhshandeh, Parviz, primary, Abednatanzi, Sara, additional, Bourda, Laurens, additional, Dalapati, Sasanka, additional, Abalymov, Anatolii, additional, Meledina, Maria, additional, Liu, Ying-Ya, additional, Skirtach, Andre G., additional, Van Hecke, Kristof, additional, Kaczmarek, Anna M., additional, and Van Der Voort, Pascal, additional

Published
2021
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36. Selective formic acid dehydrogenation at low temperature over a RuO2/COF pre-catalyst synthesized on the gram scale

Author

Gonçalves, Liliana P. L., Christensen, David Benjamin, Meledina, Maria, Salonen, Laura M., Petrovykh, Dmitri Y., Carbó-Argibay, Enrique, Sousa, Juliana P. S., Soares, O. Salomé G. P., Pereira, M. Fernando R., Kegnæs, Søren, Kolen'ko, Yury V., Gonçalves, Liliana P. L., Christensen, David Benjamin, Meledina, Maria, Salonen, Laura M., Petrovykh, Dmitri Y., Carbó-Argibay, Enrique, Sousa, Juliana P. S., Soares, O. Salomé G. P., Pereira, M. Fernando R., Kegnæs, Søren, and Kolen'ko, Yury V.

Abstract

A pre-catalyst, consisting of RuO2 nanoparticles and clusters anchored on TpBD-Me2 COF, was synthesized. During catalytic formic acid dehydrogenation, RuO2 undergoes in situ reduction to metallic Ru, forming an active and selective catalyst, which outperforms the commercial Ru–C catalyst. The chemical structure of the COF supporting material is maintained during stability testing.

Published
2020

39. Covalent triazine framework/carbon nanotube hybrids enabling selective reduction of CO2 to CO at low overpotential

Author

Laemont, Andreas, primary, Abednatanzi, Sara, additional, Derakshandeh, Parviz Gohari, additional, Verbruggen, Florian, additional, Fiset, Erika, additional, Qin, Qing, additional, Van Daele, Kevin, additional, Meledina, Maria, additional, Schmidt, Johannes, additional, Oschatz, Martin, additional, Van Der Voort, Pascal, additional, Rabaey, Korneel, additional, Antonietti, Markus, additional, Breugelmans, Tom, additional, and Leus, Karen, additional

Published
2020
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40. Selective formic acid dehydrogenation at low temperature over a RuO2/COF pre-catalyst synthesized on the gram scale

Author

Gonçalves, Liliana P. L., primary, Christensen, David B., additional, Meledina, Maria, additional, Salonen, Laura M., additional, Petrovykh, Dmitri Y., additional, Carbó-Argibay, Enrique, additional, Sousa, Juliana P. S., additional, Soares, O. Salomé G. P., additional, Pereira, M. Fernando R., additional, Kegnæs, Søren, additional, and Kolen'ko, Yury V., additional

Published
2020
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41. Covalent triazine framework/carbon nanotube hybrids enabling selective reduction of CO2 to CO at low overpotential.

Author

Laemont, Andreas, Abednatanzi, Sara, Derakshandeh, Parviz Gohari, Verbruggen, Florian, Fiset, Erika, Qin, Qing, Van Daele, Kevin, Meledina, Maria, Schmidt, Johannes, Oschatz, Martin, Van Der Voort, Pascal, Rabaey, Korneel, Antonietti, Markus, Breugelmans, Tom, and Leus, Karen

Subjects
MULTIWALLED carbon nanotubes, TRIAZINES, CARBON dioxide reduction, OVERPOTENTIAL, CARBON nanotubes, ELECTROLYTIC reduction, CHARGE exchange, HYDROXYL group
Abstract

Electrochemical reduction of CO2 provides a way to generate base chemicals from an abundant C1-source under mild conditions, whilst at the same time mitigating CO2 emissions. In this work, a novel class of tailorable, porous electrocatalysts for this process is proposed. Covalent triazine frameworks (CTFs) are grown in situ onto functionalized multiwalled carbon nanotubes. Hydroxyl groups decorating the surface of the multiwalled carbon nanotubes facilitate intimate contact between the carbon nanotubes and CTF, thus promoting efficient electron transfer. The novel hybrid materials generate CO with a faradaic efficiency up to 81% at an overpotential of 380 mV. The selectivity of the electrocatalysts could be linked to the amount of nitrogen present within the framework. [ABSTRACT FROM AUTHOR]

Published
2020
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43. Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X-ray Absorption Spectroscopy

Author

Filez, Matthias, primary, Poelman, Hilde, additional, Redekop, Evgeniy A., additional, Galvita, Vladimir V., additional, Alexopoulos, Konstantinos, additional, Meledina, Maria, additional, Ramachandran, Ranjith K., additional, Dendooven, Jolien, additional, Detavernier, Christophe, additional, Van Tendeloo, Gustaaf, additional, Safonova, Olga V., additional, Nachtegaal, Maarten, additional, Weckhuysen, Bert M., additional, and Marin, Guy B., additional

Published
2018
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45. Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X-ray Absorption Spectroscopy

Author

Filez, Matthias, Poelman, Hilde, Redekop, Evgeniy A., Galvita, Vladimir V., Alexopoulos, Konstantinos, Meledina, Maria, Ramachandran, Ranjith K., Dendooven, Jolien, Detavernier, Christophe, Van Tendeloo, Gustaaf, Safonova, Olga V., Nachtegaal, Maarten, Weckhuysen, Bert M., Marin, Guy B., Filez, Matthias, Poelman, Hilde, Redekop, Evgeniy A., Galvita, Vladimir V., Alexopoulos, Konstantinos, Meledina, Maria, Ramachandran, Ranjith K., Dendooven, Jolien, Detavernier, Christophe, Van Tendeloo, Gustaaf, Safonova, Olga V., Nachtegaal, Maarten, Weckhuysen, Bert M., and Marin, Guy B.

Abstract

Alloyed metal nanocatalysts are of environmental and economic importance in a plethora of chemical technologies. During the catalyst lifetime, supported alloy nanoparticles undergo dynamic changes which are well‐recognized but still poorly understood. High‐temperature O2–H2 redox cycling was applied to mimic the lifetime changes in model Pt13In9 nanocatalysts, while monitoring the induced changes by in situ quick X‐ray absorption spectroscopy with one‐second resolution. The different reaction steps involved in repeated Pt13In9 segregation‐alloying are identified and kinetically characterized at the single‐cycle level. Over longer time scales, sintering phenomena are substantiated and the intraparticle structure is revealed throughout the catalyst lifetime. The in situ time‐resolved observation of the dynamic habits of alloyed nanoparticles and their kinetic description can impact catalysis and other fields involving (bi)metallic nanoalloys.

Published
2018

46. Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X-ray Absorption Spectroscopy

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Filez, Matthias, Poelman, Hilde, Redekop, Evgeniy A., Galvita, Vladimir V., Alexopoulos, Konstantinos, Meledina, Maria, Ramachandran, Ranjith K., Dendooven, Jolien, Detavernier, Christophe, Van Tendeloo, Gustaaf, Safonova, Olga V., Nachtegaal, Maarten, Weckhuysen, Bert M., Marin, Guy B., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Filez, Matthias, Poelman, Hilde, Redekop, Evgeniy A., Galvita, Vladimir V., Alexopoulos, Konstantinos, Meledina, Maria, Ramachandran, Ranjith K., Dendooven, Jolien, Detavernier, Christophe, Van Tendeloo, Gustaaf, Safonova, Olga V., Nachtegaal, Maarten, Weckhuysen, Bert M., and Marin, Guy B.

Published
2018

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