The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investig... more The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead‐free alternative to Lindlar catalysts. A stereo‐selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)‐alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non‐noble copper nanoparticles for reduction of both electron‐rich and electron‐deficient, aliphatic‐substituted and aromatic‐ substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo‐ and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes.magnified image
This chapter addresses the power and possibilities provided by an appropriate combination of adva... more This chapter addresses the power and possibilities provided by an appropriate combination of advanced characterization techniques in understanding the environment of metal ions in different metal-zeolites, as well as in the role played by them in different catalytic reactions. Three different classes of materials are considered as case studies: (1) Cu-zeolites, where CuI and CuII ions are mainly present as counterions; (2) Fe-zeolites, often containing a wide variety of isolated, oligonuclear, and aggregated (oxide/hydroxide) FeII/FeIII species; and (3) TS-1, which is the closest to a “single-site” catalyst, mainly containing framework TiIV sites. TS-1 is studied in relation to its activity in the propene epoxidation reaction in the presence of aqueous H2O2, while Cu- and Fe-zeolites are here considered in relation to the direct conversion of methane to methanol (MTM) (a so-called dream reaction) with O2, N2O, or H2O2 as oxidizing agents. Main focus is into the nature of the active site precursors (i.e., mono or di-/trinuclear ions, oxidation state, and local environment) and into the electronic and geometric structure of the oxo species formed upon interaction with the oxidizing agents. Moreover, examples about in situ or operando experiments following changes during the reaction are reviewed. The main considered techniques are X-ray absorption spectroscopy (XAS) and resonance Raman (rR) and diffuse reflectance UV-Vis spectroscopies, often coupled to density functional theory (DFT) modeling. Depending on the studied system, results obtained with infrared, Mossbauer, X-ray emission (XES) and electron paramagnetic resonance (EPR) spectroscopies are also described. The discussion includes the open debates, the main drawbacks and potentialities of the techniques, and the related characterization challenges.
A series of mono and bimetallic catalysts based on a Fe-Ag mixture deposited on mordenite was pre... more A series of mono and bimetallic catalysts based on a Fe-Ag mixture deposited on mordenite was prepared by ion-exchange and evaluated in the catalytic activity test of the de-NOx reaction in the presence of CO/C3H6. The activity results showed that the most active samples were the Fe-containing ones, and at high temperatures, a co-promoter effect of Ag on the activity of Fe catalysts was also observed. The influence of the order of cation deposition on catalysts formation and their physicochemical properties was studied by FTIR (Fourier Transform Infrared Spectroscopy) of adsorbed NO, XANES (X-ray Absorption Near-Edge Structure), and EXAFS (Extended X-ray Absorption Fine Structure) and discussed in terms of the state of iron. Results of Fe K-edge XANES oscillations showed that, in FeMOR catalysts, iron was present in a disordered state as Fe3+ and Fe2+. In FeAgMOR, the prevailing species was Fe3+, while in the AgFeMOR catalyst, the state of iron was intermediate or mixed between FeMO...
The development of new strategies for spatially controllable immobilization has encouraged the pr... more The development of new strategies for spatially controllable immobilization has encouraged the preparation of novel catalysts based on the organic-inorganic hybrid concept. In the present paper, a Cu-based multi-structured silica catalyst has been prepared and fully characterized. The inclusion of Cu(II) in β-cyclodextrins has been exploited with the double aim to stabilize the metal and to act as a source of Cu(I) catalytic sites. Multi-technique characterization by infrared, UV-visible, electron microscopy and X-ray absorption spectroscopies of the fresh and exhaust catalysts provided information on the local structure, redox properties and stability of the investigated hybrid systems. The catalytic system showed that copper nanospecies were dispersed on the support and hardly affected by the catalytic tests, confirming the stabilizing effect of β-CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Ove...
Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydroth... more Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe2+ or Fe3+ salts (Fe2+ZP and Fe3+ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3H6. Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species’ nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+/Fe3+ extra-framework sites and FexOy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ZP showed a higher intensity of nitrosonium (NO+) species, without a corr...
A multi-technique in situ study of the reaction between NO and Cu-nitrates in the Cu-CHA deNOx ca... more A multi-technique in situ study of the reaction between NO and Cu-nitrates in the Cu-CHA deNOx catalyst yields novel structural and spectroscopic insights into the equilibrium between Cu-nitrates and Cu-nitrites, which was proposed as key step in the NH3-SCR cycle.
In order to design valid protocols for drug release via nanocarriers, it is essential to know the... more In order to design valid protocols for drug release via nanocarriers, it is essential to know the mechanisms of cell internalization, the interactions with organelles, and the intracellular permanence and degradation of nanoparticles (NPs) as well as the possible cell alteration or damage induced. In the present study, the intracellular fate of liposomes, polymeric NPs and mesoporous silica NPs (MSN) has been investigated in an in vitro cell system by fluorescence and transmission electron microscopy. The tested nanocarriers proved to be characterized by specific interactions with the cell: liposomes enter the cells probably by fusion with the plasma membrane and undergo rapid cytoplasmic degradation; polymeric NPs are internalized by endocytosis, occur in the cytoplasm both enclosed in endosomes and free in the cytosol, and then undergo massive degradation by lysosome action; MSN are internalized by both endocytosis and phagocytosis, and persist in the cytoplasm enclosed in vacuole...
... This was performed in this work by correcting the position and extinction coefficient as deta... more ... This was performed in this work by correcting the position and extinction coefficient as detailed by Makarova et al. 22-24 and Martins et al. ... This result will be discussed in the following section together with the results obtained by using ammonia as the probe molecule. 3.2. ...
ABSTRACT The use of XANES spectroscopy, both in classical and in dispersive geometries, is illust... more ABSTRACT The use of XANES spectroscopy, both in classical and in dispersive geometries, is illustrated for the study of copper-based catalysts under in situ or in operando conditions. As case studies, copper-exchanged MFI zeolites and CuCl2/γ-Al2O3 systems are considered. In the former case, in situ XANES spectroscopy was used to characterise well defined complexes (Cu+N2, Cu+(CO)3, Cu+(NH3)(CO) and Cu+(NO)2) formed on copper ions inside the zeolite cavities under controlled conditions. From these results, useful information concerning the symmetry of the formed complexes can readily be gained. The latter case shows how the use of dispersive XANES spectroscopy allows to follow, in real time, the evolution of a system in working conditions. The simultaneous determination of the catalyst activity and of the average oxidation state of copper in the catalyst allows the evolution of a system in working conditions to be followed in real time. The criteria used for the quantification of the Cu(I) and Cu(II) fraction from XANES spectra are discussed in detail.
FTIR spectroscopy of adsorbed molecules such as CO and NO was used to monitor the nature of cobal... more FTIR spectroscopy of adsorbed molecules such as CO and NO was used to monitor the nature of cobalt centres in Co-containing aluminophosphates (AlPOs) and silicoaluminophosphates (SAPOs) with chabasite-like structures. The samples were synthesized by following a facile route during which the cobalt ions were directly inserted in the synthesis gels. These studies show that Co2+ ions are located in framework
The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investig... more The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead‐free alternative to Lindlar catalysts. A stereo‐selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)‐alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non‐noble copper nanoparticles for reduction of both electron‐rich and electron‐deficient, aliphatic‐substituted and aromatic‐ substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo‐ and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes.magnified image
This chapter addresses the power and possibilities provided by an appropriate combination of adva... more This chapter addresses the power and possibilities provided by an appropriate combination of advanced characterization techniques in understanding the environment of metal ions in different metal-zeolites, as well as in the role played by them in different catalytic reactions. Three different classes of materials are considered as case studies: (1) Cu-zeolites, where CuI and CuII ions are mainly present as counterions; (2) Fe-zeolites, often containing a wide variety of isolated, oligonuclear, and aggregated (oxide/hydroxide) FeII/FeIII species; and (3) TS-1, which is the closest to a “single-site” catalyst, mainly containing framework TiIV sites. TS-1 is studied in relation to its activity in the propene epoxidation reaction in the presence of aqueous H2O2, while Cu- and Fe-zeolites are here considered in relation to the direct conversion of methane to methanol (MTM) (a so-called dream reaction) with O2, N2O, or H2O2 as oxidizing agents. Main focus is into the nature of the active site precursors (i.e., mono or di-/trinuclear ions, oxidation state, and local environment) and into the electronic and geometric structure of the oxo species formed upon interaction with the oxidizing agents. Moreover, examples about in situ or operando experiments following changes during the reaction are reviewed. The main considered techniques are X-ray absorption spectroscopy (XAS) and resonance Raman (rR) and diffuse reflectance UV-Vis spectroscopies, often coupled to density functional theory (DFT) modeling. Depending on the studied system, results obtained with infrared, Mossbauer, X-ray emission (XES) and electron paramagnetic resonance (EPR) spectroscopies are also described. The discussion includes the open debates, the main drawbacks and potentialities of the techniques, and the related characterization challenges.
A series of mono and bimetallic catalysts based on a Fe-Ag mixture deposited on mordenite was pre... more A series of mono and bimetallic catalysts based on a Fe-Ag mixture deposited on mordenite was prepared by ion-exchange and evaluated in the catalytic activity test of the de-NOx reaction in the presence of CO/C3H6. The activity results showed that the most active samples were the Fe-containing ones, and at high temperatures, a co-promoter effect of Ag on the activity of Fe catalysts was also observed. The influence of the order of cation deposition on catalysts formation and their physicochemical properties was studied by FTIR (Fourier Transform Infrared Spectroscopy) of adsorbed NO, XANES (X-ray Absorption Near-Edge Structure), and EXAFS (Extended X-ray Absorption Fine Structure) and discussed in terms of the state of iron. Results of Fe K-edge XANES oscillations showed that, in FeMOR catalysts, iron was present in a disordered state as Fe3+ and Fe2+. In FeAgMOR, the prevailing species was Fe3+, while in the AgFeMOR catalyst, the state of iron was intermediate or mixed between FeMO...
The development of new strategies for spatially controllable immobilization has encouraged the pr... more The development of new strategies for spatially controllable immobilization has encouraged the preparation of novel catalysts based on the organic-inorganic hybrid concept. In the present paper, a Cu-based multi-structured silica catalyst has been prepared and fully characterized. The inclusion of Cu(II) in β-cyclodextrins has been exploited with the double aim to stabilize the metal and to act as a source of Cu(I) catalytic sites. Multi-technique characterization by infrared, UV-visible, electron microscopy and X-ray absorption spectroscopies of the fresh and exhaust catalysts provided information on the local structure, redox properties and stability of the investigated hybrid systems. The catalytic system showed that copper nanospecies were dispersed on the support and hardly affected by the catalytic tests, confirming the stabilizing effect of β-CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Ove...
Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydroth... more Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe2+ or Fe3+ salts (Fe2+ZP and Fe3+ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3H6. Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species’ nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+/Fe3+ extra-framework sites and FexOy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ZP showed a higher intensity of nitrosonium (NO+) species, without a corr...
A multi-technique in situ study of the reaction between NO and Cu-nitrates in the Cu-CHA deNOx ca... more A multi-technique in situ study of the reaction between NO and Cu-nitrates in the Cu-CHA deNOx catalyst yields novel structural and spectroscopic insights into the equilibrium between Cu-nitrates and Cu-nitrites, which was proposed as key step in the NH3-SCR cycle.
In order to design valid protocols for drug release via nanocarriers, it is essential to know the... more In order to design valid protocols for drug release via nanocarriers, it is essential to know the mechanisms of cell internalization, the interactions with organelles, and the intracellular permanence and degradation of nanoparticles (NPs) as well as the possible cell alteration or damage induced. In the present study, the intracellular fate of liposomes, polymeric NPs and mesoporous silica NPs (MSN) has been investigated in an in vitro cell system by fluorescence and transmission electron microscopy. The tested nanocarriers proved to be characterized by specific interactions with the cell: liposomes enter the cells probably by fusion with the plasma membrane and undergo rapid cytoplasmic degradation; polymeric NPs are internalized by endocytosis, occur in the cytoplasm both enclosed in endosomes and free in the cytosol, and then undergo massive degradation by lysosome action; MSN are internalized by both endocytosis and phagocytosis, and persist in the cytoplasm enclosed in vacuole...
... This was performed in this work by correcting the position and extinction coefficient as deta... more ... This was performed in this work by correcting the position and extinction coefficient as detailed by Makarova et al. 22-24 and Martins et al. ... This result will be discussed in the following section together with the results obtained by using ammonia as the probe molecule. 3.2. ...
ABSTRACT The use of XANES spectroscopy, both in classical and in dispersive geometries, is illust... more ABSTRACT The use of XANES spectroscopy, both in classical and in dispersive geometries, is illustrated for the study of copper-based catalysts under in situ or in operando conditions. As case studies, copper-exchanged MFI zeolites and CuCl2/γ-Al2O3 systems are considered. In the former case, in situ XANES spectroscopy was used to characterise well defined complexes (Cu+N2, Cu+(CO)3, Cu+(NH3)(CO) and Cu+(NO)2) formed on copper ions inside the zeolite cavities under controlled conditions. From these results, useful information concerning the symmetry of the formed complexes can readily be gained. The latter case shows how the use of dispersive XANES spectroscopy allows to follow, in real time, the evolution of a system in working conditions. The simultaneous determination of the catalyst activity and of the average oxidation state of copper in the catalyst allows the evolution of a system in working conditions to be followed in real time. The criteria used for the quantification of the Cu(I) and Cu(II) fraction from XANES spectra are discussed in detail.
FTIR spectroscopy of adsorbed molecules such as CO and NO was used to monitor the nature of cobal... more FTIR spectroscopy of adsorbed molecules such as CO and NO was used to monitor the nature of cobalt centres in Co-containing aluminophosphates (AlPOs) and silicoaluminophosphates (SAPOs) with chabasite-like structures. The samples were synthesized by following a facile route during which the cobalt ions were directly inserted in the synthesis gels. These studies show that Co2+ ions are located in framework
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Papers by G. Berlier