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Two series of zeolite Y were prepared with varying particle size (estimated 100 or 400 nm) by applying different synthesis gel composition ratios as well as different ageing and hydrothermal steps. Copper-containing zeolites Y were obtained through ion exchange, thoroughly characterized and tested for the selective catalytic reduction with NH3 (NH3-SCR-DeNOx). The catalytic activity of the prepared materials varied significantly due to the different nature of copper species. Results show that catalysts CuY 0h-A and CuY-24h-A (approx. particles size 2676 and 475 nm, respectively) facilitate a higher NO conversion both in the presence and absence of water vapor, exhibiting however stronger N2O formation above 250 °C. On the other hand, nearly X-ray amorphous Y-0h-B and Y-24h-B after ion- exchange led to decreased activity of CuY-0h-B and CuY-24h-B (approx. particles size 345 and 128 nm, respectively). Additional insight into the activity of both catalyst were obtained through in situ DR UV-Vis spectroscopy.

The design of sustainable procedures for the preparation of cobalt/carbon-based materials as an anode for hydrogen fuel production through electrocatalytic water splitting has attracted much interest in the last few years. Herein, a novel environmentally friendly approach for the development of stable and active catalysts for the oxygen evolution reaction (OER) is reported. In detail, the methodology aimed at developing a sequence of composites having a low cobalt loading ( MW/US > MW > conventional heating, with the best sample requiring an overpotential of 365 mV to deliver a current density of 10 mA cm_2 and a Tafel slope of 58 mV dec_1.

The speciation of framework-interacting CuII sites in Cu-chabazite zeolite catalysts active in the selective catalytic reduction of NOx with NH3 is studied, to investigate the influence of the Al content on the copper structure and their reactivity towards a NO/O2 mixture. To this aim, three samples with similar Cu densities and different Si/Al ratios (5, 15 and 29) were studied using in situ X-ray absorption spectroscopy (XAS), FTIR and diffuse reflectance UV-Vis during pretreatment in O2 followed by the reaction. XAS and UV-Vis data clearly show the main presence of Z2CuII sites (with Z representing a framework negative charge) at a low Si/Al ratio, as predicted. EXAFS wavelet transform analysis showed a non-negligible fraction of proximal Z2CuII monomers, possibly stabilized into two 6-membered rings within the same cage. These sites are not able to form Cu-nitrates by interaction with NO/O2. By contrast, framework-anchored Z[CuII(NO3)] complexes with a chelating bidentate structure are formed in samples with a higher Si/Al ratio, by reaction of NO/O2 with Z[CuII(OH)] sites or structurally similar mono- or multi-copper Zx[CuIIxOy] sites. Linear combination fit (LCF) analysis of the XAS data showed good agreement between the fraction of Z[CuII(OH)]/Zx[CuIIxOy] sites formed during activation in O2 and that of Z[CuII(NO3)] complexes formed by reaction with NO/O2, further confirming the chemical inertia of Z2CuII towards these reactants in the absence of solvating NH3 molecules., The speciation of the CuII sites in Cu-CHA catalysts for NH3-SCR is studied, to investigate the influence of the Al content on the structure and reactivity of these sites in a NO/O2 mixture.

The NH3-mediated selective catalytic reduction (NH3-SCR) of NOx over Cu-ion-exchanged chabazite (Cu-CHA) catalysts is the basis of the technology for abatement of NOx from diesel vehicles. A crucial step in this reaction is the activation of oxygen. Under conditions for low-temperature NH3-SCR, oxygen only reacts with CuI ions, which are present as mobile CuI diamine complexes [CuI(NH3)2]+. To determine the structure and reactivity of the species formed by oxidation of these CuI diamine complexes with oxygen at 200 °C, we have followed this reaction, using a Cu-CHA catalyst with a Si/Al ratio of 15 and 2.6 wt% Cu, by X-ray absorption spectroscopies (XANES and EXAFS) and diffuse reflectance UV-Vis spectroscopy, with the support of DFT calculations and advanced EXAFS wavelet transform analysis. The results provide unprecedented direct evidence for the formation of a [Cu2(NH3)4O2]2+ mobile complex with a side-on μ-η2,η2-peroxo diamino dicopper(II) structure, accounting for 80–90% of the total Cu content. These [Cu2(NH3)4O2]2+ are completely reduced to [CuI(NH3)2]+ at 200 °C in a mixture of NO and NH3. Some N2 is formed as well, which suggests the role of the dimeric complexes in the low-temperature NH3-SCR reaction. The reaction of [Cu2(NH3)4O2]2+ complexes with NH3 leads to a partial reduction of the Cu without any formation of N2. The reaction with NO results in an almost complete reduction to CuI, under the formation of N2. This indicates that the low-temperature NH3-SCR reaction proceeds via a reaction of these complexes with NO.

The direct methane to methanol (DMTM) conversion is often referred to as a ‘dream reaction’ with enormous potential to alter energy sector and chemical industry. After O2-activation, Cu-exchanged zeolites form CuxOy species that activate CH4 and release it in the form of CH3OH upon interaction with H2O. Despite extensive research efforts in the last years, several questions concerning the influence of materials composition and process parameters on the reaction mechanism remain open. Herein, we characterize Cu-MOR zeolites with different composition by operando X-ray absorption spectroscopy (XAS), monitoring their spectroscopic response under two characteristic DMTM reaction protocols varied in the duration of the key reaction steps. Linear Combination Fit (LCF) analysis of the time-resolved X-ray absorption near edge structure (XANES) spectra collected during CH4-loading and steam-assisted CH3OH extraction enabled to quantify the abundance of different Cu species during these two steps. Data analysis revealed a positive linear correlation between the methanol yield generated per incorporated copper and the Cu(I) component formed during the CH4-loading step. Cu(I) development during CH4-loading is accompanied by modifications in the extended X-ray absorption fine structure (EXAFS) spectra suggesting substantial rearrangement in the active site structure. The obtained results provide new mechanistic insights for the DMTM over Cu-MOR.

The local structural and electronic properties of Cu sites during the direct conversion of methane to methanol with molecular oxygen was followed by X-ray absorption spectroscopy (XAS) on a set of Cu-zeolites with different topology (large pore MOR and small pore CHA frameworks) and similar chemical composition (Si/Al ∼ 11 and 12, respectively). Two low loading (LL) and high loading (HL) samples were prepared by ion exchange, and their methanol productivity measured in laboratory fixed bed reactor tests, resulting in selectivity higher than 85%. Both Cu-MOR samples outperformed Cu-CHA ones, resulting in 0.28 and 0.26 molCH3OH/molCu for the LL (Cu/Al = 0.13) and HL (Cu/Al = 0.36) samples, vs 0.10 and 0.17 molCH3OH/molCu for LL and HL Cu-CHA, respectively (Cu/Al = 0.16 and 0.49). The evolution of Cu oxidation state and local coordination environment was followed in all the reaction steps (O2 activation, flush with He, CH4 dosage and subsequent CH3OH desorption by applying a wet stream) both during temperature changes (ramp in O2 up to 500 °C, cooling to 200 °C for subsequent steps, etc.) and in steady-state conditions. Strong similarities were observed in the local structure of Cu sites in all samples, which showed similar redox dynamics during O2 activation and subsequent cooling to 200 °C. Even though only qualitative considerations can be made on the overall spectral evolution, XANES indicates that not all the Cu(I) formed during CH4 loading belongs to active sites.

Temperature programmed reduction with NO (NO-TPR) is introduced as a characterization method, by monitoring the reduction of CuII to CuI in a mixture of NH3 and NO. Since the NO-TPR method is based on the oxidation and reduction half cycles of the NH3-SCR reaction, quantitative information about the amount of active Cu in Cu-CHA is obtained. Furthermore, information on the stability and reactivity of reaction intermediates in the NH3-SCR cycle is obtained as well. The reduction of the Cu is followed by monitoring the consumption of NO, after oxidation of the catalyst in O2 or a mixture of NO and O2 to form the CuII state. Two distinct states of the Cu are revealed. The first state, corresponding to the reduction of a Cu-oxide species, is reduced around 130 °C and is observed at low Cu content only. The second state corresponds to the reduction of a Cu-nitrate species around 200–230 °C. The low-temperature activity of Cu-chabazite catalysts with low Cu content show the same trend as the Cu-nitrate species observed in NO-TPR. The fraction of Cu-oxide in NO-TPR decreases with increasing Cu content, leading to a non-linear dependence of the NH3-SCR activity on the Cu-content. At high Cu content, all Cu forms a stable Cu-nitrate species, and the NH3-SCR activity becomes proportional to the Cu content. This agrees well with the known behavior of Cu-CHA catalysts, indicating that NO-TPR seems to be a viable method for the characterization of Cu-CHA materials as NH3-SCR catalysts.

ispartof: ADVANCED SYNTHESIS & CATALYSIS vol:363 issue:11 pages:2850-2860 status: published

Ammonia-mediated selective catalytic reduction (NH3-SCR) using Cu-exchanged chabazite zeolites as catalysts is one of the leading technologies for NOx removal from exhaust gases, with CuII/CuI redox cycles being the basis of the catalytic reaction. The amount of CuII ions reduced by NO/NH3 can be quantified by the consumption of NO during temperature-programmed reduction experiments (NO-TPR). In this article, we show the capabilities of in situ X-ray absorption near-edge spectroscopy (XANES), coupled with multivariate curve resolution (MCR) and principal component analysis (PCA) methods, in following CuII/CuI speciation during reduction in NO/NH3 after oxidation in NO/O2 at 50 °C on samples with different copper loading and pretreatment conditions. Our XANES results show that during the NO/NH3 ramp CuII ions are fully reduced to CuI in the 50–290 °C range. The number of species involved in the process, their XANES spectra and their concentration profiles as a function of the temperature were obtained by MCR and PCA. Mixed ligand ammonia solvated complexes [CuII(NH3)3(X)]+ (X = OH−/O− or NO3−) are present at the beginning of the experiment, and are transformed into mobile [CuI(NH3)2]+ complexes: these complexes lose an NH3 ligand and become framework-coordinated above 200 °C. In the process, multiple CuII/CuI reduction events are observed: the first one around 130 °C is identified with the reduction of [CuII(NH3)3(OH/O)]+ moieties, while the second one occurs around 220–240 °C and is associated with the reduction of the ammonia-solvated Cu-NO3− species. The nitrate concentration in the catalysts is found to be dependent on the zeolite Cu loading and on the applied pretreatment conditions. Ammonia solvation increases the number of CuII sites available for the formation of nitrates, as confirmed by infrared spectroscopy.

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 &beta, 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 &beta, CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Overall, we demonstrate a feasible approach to efficiently anchor Cu(II) species and to obtain a reusable single-site hybrid catalyst well suited for Cu(I)-catalyzed alkyne-azide cycloaddition.

The direct conversion of methane to methanol (MTM) is a reaction that has the potential to disrupt a great part of the synthesis gas-derived chemical industry. However, despite many decades of research, active enough catalysts and suitable processes for industrial application are still not available. Recently, several copper-exchanged zeolites have shown considerable activity and selectivity in the direct MTM reaction. Understanding the nature of the active site in these materials is essential for any further development in the field. Herein, we apply multivariate curve resolution analysis of X-ray absorption spectroscopy data to accurately quantify the fraction of active Cu in Cu-MOR (MOR = mordenite), allowing an unambiguous determination of the active site nuclearity as a dicopper site. By rationalizing the compositional parameters and reaction conditions, we achieve the highest methanol yield per Cu yet reported for MTM over Cu-zeolites, of 0.47 mol/mol.

We have prepared and evaluated the physico-chemical and biological properties of four different hyaluronated mesoporous silica nanoparticles (MSNs) samples (MSN/HA). Hyaluronic acid (HA) with two different molecular weights (200 and 6.4 kDa) was used for the conjugation of aminopropyl-functionalized MSN (NH2-MSN), following two different procedures. Namely, samples HA200A and HA6.4A were prepared by reacting activated HA with NH2-MSN (method A), while samples HA200B and HA6.4B were obtained carrying out HA activation in the presence of the nanoparticles (method B). The four samples showed similar hydrophilicity, but clear differences in the HA loading, textural properties, surface charge and stability of the suspensions. More in detail, conjugation using low molecular weight HA with method A resulted in low HA loading, with consequent scarce effects on dispersity and stability in physiological media. The highest yield and corresponding best performances were obtained with method B using high molecular weight HA. HA loading and molecular weight also influenced in a concerted way the biological response towards the MSNs of CD44 target cancer cells (CD44+) and control cells (CD44−): MDA-MB-231 and A2780, respectively. The absence of cytotoxicity was assessed. Moreover, the targeting ability of the best performing MSN/HA was confirmed by cellular uptake studies.

The interaction of water molecules with the surface of hybrid silica-based mesoporous materials is studied by 29 Si, 1 H and 13 C solid-state NMR and IR spectroscopy, with the support of ab initio calculations. The surface of aminopropyl-grafted mesoporous silica nanoparticles is studied in the dehydrated state and upon interaction with controlled doses of water vapour. Former investigations described the interactions between aminopropyl and residual SiOH groups; the present study shows the presence of hydrogen-bonded species (SiOH to NH2 ) and weakly interacting "free" aminopropyl chains with restricted mobility, together with a small amount of protonated NH3+ groups. The concentration of the last-named species increased upon interaction with water, and this indicates reversible and fast proton exchange from water molecules to a fraction of the amino groups. Herein, this is discussed and explained for the first time, by a combination of experimental and theoretical approaches.

We present for the first time the application of metal-organic framework (MOF) mixed-matrix disks (MMD) for the automated flow-through solid-phase extraction (SPE) of environmental pollutants. Zirconium terephthalate UiO-66 and UiO-66-NH2 MOFs with different size (90, 200 and 300nm) have been incorporated into mechanically stable polyvinylidene difluoride (PVDF) disks. The performance of the MOF-MMDs for automated SPE of seven substituted phenols prior to HPLC analysis has been evaluated using the sequential injection analysis technique. MOF-MMDs enabled the simultaneous extraction of phenols with the concomitant size exclusion of molecules of larger size. The best extraction performance was obtained using a MOF-MMD containing 90nm UiO-66-NH2 crystals. Using the selected MOF-MMD, detection limits ranging from 0.1 to 0.2μgL-1 were obtained. Relative standard deviations ranged from 3.9 to 5.3% intra-day, and 4.7-5.7% inter-day. Membrane batch-to-batch reproducibility was from 5.2 to 6.4%. Three different groundwater samples were analyzed with the proposed method using MOF-MMDs, obtaining recoveries ranging from 90 to 98% for all tested analytes.

The synthesis, characterization and catalytic performance of offretite with four distinct crystal morphologies (oval, hexagonal, broccoli-like, and spherical) are presented. As a member of the ABC-6 family of zeolite structures, offretite is likely to form intergrowths which can affect its shape-selective properties. Herein, a combination of experiments (SC-XRD, PXRD, benzene uptake and the methanol-to-hydrocarbon conversion) allows the determination of the mechanism and fraction of twinning. It is demonstrated that the catalysts with the same crystal aspect ratio (AR = 3) yield product spectra dominated by C2–C4 aliphatics. Such product selectivity is associated with zeolites with an 8-ring channel system. Interestingly, a significant production of bulky aromatics is seen for the catalyst with the spherical morphology (AS = 1.1) which is a manifestation of the 12-ring pore system of the OFF framework topology. This constitutes the first report of this behavior. The particular display of product shape selectivity can be ascribed to the catalyst particle morphology.

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&rsquo, 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 correlation to NO storage and conversion, pointing to the reactivity of small FexOy aggregates in providing oxygen atoms for the NO to NO+ reaction. The same sites are proposed to be responsible for the higher production of CO2 observed on this sample, and thus to be detrimental to the activity in NO SCR.

Copper exchanged CHA zeolites were investigated by in situ Diffuse Reflectance UV–vis-NIR spectroscopy in order to study the evolution of the copper environment in respect to the sample composition (2 samples differing in Si/Al and Cu content) and the activation procedure (in O2 or N2 from room temperature to 400 °C). In situ measurements allowed showing the different behavior of the two samples, both in the d-d and Ligand to Metal Charge Transfer regions, confirming a strong effect of the lattice composition to determine the copper environment and its reactivity. One of the two sample (Si/Al = 15 and Cu/Al = 0.5) was further investigated, in order to clarify the nature of the Cu-oxo species, formed along activation in oxygen. To shed light on this point, in situ measurements starting from a reduced form of the sample, obtained by activation in inert atmosphere at high temperature, were also considered. Additional suggestions on the nature of these species were obtained by resonant Raman measurements conducted in controlled atmosphere.

This contribution clarifies the overoxidation-preventing key step in the methane-to-methanol (MTM) conversion over copper mordenite zeolites. We followed the methane-to-methanol conversion over copper mordenite zeolites by NMR spectroscopy supported by DRIFTS to show that surface methoxy groups (SMGs) located at zeolite Brønsted sites are the key intermediates. The SMGs with chemical shift of 59 ppm are identical to those formed on a copper-free reference zeolite after reaction with methanol and react with water, methanol, or carbon monoxide to yield methanol, dimethyl ether, and acetate. This reactivity corroborates the location of SMGs at Brønsted sites. We find no evidence for stable SMGs directly at copper sites and explain mechanistically why H-form mordenites outperform their Na-form analogues. This finding is of interest for any future process that tries to trap the intermediate methane oxidation product towards methanol.

Aim: To elucidate whether different cytokinetic features (i.e., presence or absence of mitotic activity) may influence cell uptake and distribution of nanocarriers, in vitro tests on liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were carried out on C2C12 murine muscle cells either able to proliferate as myoblasts (cycling cells) or terminally differentiate into myotubes (noncycling cells). Materials & methods: Cell uptake and intracellular fate of liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were investigated by confocal fluorescence microscopy and transmission electron microscopy. Results: Nanocarrier internalization and distribution were similar in myoblasts and myotubes; however, myotubes demonstrated a lower uptake capability. Conclusion: All nanocarriers proved to be suitably biocompatible for both myoblasts and myotubes. The lower uptake capability of myotubes is probably due to different plasma membrane composition related to the differentiation process.

The use of nanoparticles as drug carriers in the field of skeletal muscle diseases has been poorly addressed and the interaction of nanoparticles with skeletal muscle cells has been investigated almost exclusively on C2C12 murine myoblasts. In this study we investigated the effects poly(lactide-co-glycolide) nanoparticles, mesoporous silica nanoparticles and liposomes, on the viability of primary human myoblasts and analyzed their cellular uptake and intracellular distribution in both primary human myoblasts and myotubes. Our data demonstrate that poly(lactide-co-glycolide) nanoparticles do not negatively affect myoblasts viability, contrarily to mesoporous silica nanoparticles and liposomes that induce a decrease in cell viability at the highest doses and longest incubation time. Poly(lactide-co-glycolide) nanoparticles and mesoporous silica nanoparticles are internalized by endocytosis, poly(lactide-co-glycolide) nanoparticles undergo endosomal escape whereas mesoporous silica nanoparticles always occur within vacuoles. Liposomes were rarely observed within the cells. The uptake of all tested nanoparticles was less prominent in primary human myotubes as compared to myoblasts. Our findings represent the first step toward the characterization of the interaction between nanoparticles and primary human muscle cells and suggest that poly(lactide-co-glycolide) nanoparticles might find an application for drug delivery to skeletal muscle.

The role of anatase TiO2 on the performance of VOx-TiO2 is studied by in situ spectroscopies on a series of catalysts with 1.9–9.7 V at/nm2. At low coverages, VOx is preferentially located at defect sites, spreading on the main TiO2 {101} and {100} facets at intermediate coverages. Bronsted sites concentration is maximum around 6 V atoms/nm2, and EPR shows a significant amount of V4+ at intermediate VOx densities, indicating the influence of TiO2 on their reducibility. The activity is proportional to the square of the VOx density up to 5.8 V atoms/nm2. All catalysts show the same activation energy for NH3-SCR of 56.9 ± 1.0 kJ/mol in the temperature range 160−280 °C, indicating that the reaction path does not change in the studied V coverage range. The activity does not follow the observed trends for Bronsted acid sites or reducibility, and it seems that the ability to form V-pairs is the only requirement for catalytic activity.

The small-pore Cu-CHA zeolite is today the object of intensive research efforts to rationalize its outstanding performance in the NH3-assisted selective catalytic reduction (SCR) of harmful nitrogen oxides and to unveil the SCR mechanism. Herein we exploit operando X-ray spectroscopies to monitor the Cu-CHA catalyst in action during NH3-SCR in the 150-400 °C range, targeting Cu oxidation state, mobility, and preferential N or O ligation as a function of reaction temperature. By combining operando XANES, EXAFS, and vtc-XES, we unambiguously identify two distinct regimes for the atomic-scale behavior of Cu active-sites. Low-temperature SCR, up to ∼200 °C, is characterized by balanced populations of Cu(I)/Cu(II) sites and dominated by mobile NH3-solvated Cu-species. From 250 °C upward, in correspondence to the steep increase in catalytic activity, the largely dominant Cu-species are framework-coordinated Cu(II) sites, likely representing the active sites for high-temperature SCR.

International audience; Mesoporous ionosilicas bearing ammonium groups appear as versatile adsorbent for anionic drugs. High amounts of the anionic drugs diclofenac and sulindac are irreversibly trapped within the materials whereas neutral species are hardly adsorbed. Our results open the route towards new ionic materials for wastewater treatment via ion exchange.

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 FeMOR and FeAgMOR. The Fe K-edge EXAFS results were characteristic of a disordered phase, the first coordination sphere being asymmetric with two different Fe-O distances. In FeAgMOR and AgFeMOR, coordination of Fe-O was similar to Fe2O3 with a few amount of Fe2+ species. We may conclude that, in the bimetallic FeAgMOR and AgFeMOR samples, a certain amount of tetrahedral Al3+ ions in the mordenite framework is replaced by Fe3+ ions, confirming the previous reports that these species are active sites for the de-NOx reaction. Based on the thermodynamic analysis and experimental data, also, it was confirmed that the order of deposition of the components influenced the mechanism of active sites&rsquo, formation during the two steps ion-exchange synthesis.

On our route towards a more sustainable future, the use of stranded and underutilized natural gas to produce chemicals would be a great aid in mitigating climate change, due to the reduced CO2 emissions in comparison to using petroleum. In this study, we investigate the performance of Cu-exchanged SSZ-13 and SAPO-34 microporous materials in the stepwise, direct conversion of methane to methanol. With the use of X-ray absorption spectroscopy, infrared (in combination with CO adsorption) and Raman spectroscopy, we compared the structure&ndash, activity relationships for the two materials. We found that SSZ-13 performed significantly better than SAPO-34 at the standard conditions. From CH4-TPR, it is evident that SAPO-34 requires a higher temperature for CH4 oxidation, and by changing the CH4 loading temperature from 200 to 300 &deg, C, the yield (&mu, mol/g) of SAPO-34 was increased tenfold. As observed from spectroscopy, both three- and four-fold coordinated Cu-species were formed after O2-activation, among them, the active species for methane activation. The Cu speciation in SAPO-34 is distinct from that in SSZ-13. These deviations can be attributed to several factors, including the different framework polarities, and the amount and distribution of ion exchange sites.

Pentamidine (PTM), an antiprotozoal agent used in clinics as pentamidine isethionate salt (PTM-S), recently showed high potential also for the treatment of cancer and myotonic dystrophy type I. However, a severe limit to the systemic administration of PTM is represented by its nephrotoxicity, leading to the need for a system able to achieve a controlled release of the drug. In this study, mesoporous silica nanoparticles (MSNs) were employed for the first time to encapsulate PTM. PTM-S was first used for loading experiments into bare (MSN-OH) and aminopropyl, cyanopropyl and carboxypropyl-functionalized MSNs (MSN-NH2, MSN-CN and MSN-COOH respectively) but it was not adequately loaded in any MSNs. The free base of PTM (PTM-B) was then obtained from PTM-S and successfully loaded into MSNs. Specifically, MSN-COOH exhibited the highest loading capacity. In vitro evaluation of PTM-B kinetic release from the different MSNs was carried out. An influence of the functional groups in slowing the release of the drug, when compared to bare MSNs was observed. Altogether, these results demonstrate that MSN-COOH could be a promising system to achieve a controlled release of PTM.

In this work, we show the potentiality of operando FTIR spectroscopy to follow the formation of CuII -(N,O) species on Cu exchanged chabazite zeolites (Cu-CHA), active for the selective catalytic reduction of NOx with NH3 (NH3 -SCR). In particular, we investigated the reaction of NO and O2 at low temperature (200 and 50 °C) on a series of Cu-CHA zeolites with different composition (Si/Al and Cu/Al ratios), to investigate the nature of the formed copper nitrates, which have been proposed to be key intermediates in the oxidation part of the SCR cycle. Our results show that chelating bidentate nitrates are the main structures formed at 200 °C. At lower temperature a mixture of chelating and monodentate nitrates are formed, together with the nitrosonium ion NO+ , whose amount was found to be proportional to the zeolite Bronsted site concentration. Nitrates were found to mainly form with CuII ions stabilized by one negative framework charge (Z), Z-[Cu(OH]I or Z-[Cu(O2 ]I , without involvement of Z2 -CuII ones. This evidence, together with the absence of bridging nitrates in samples with high probability for Cu-Cu pairs, indicate that the nitrate ligands are not able to mobilize copper ions, at variance with what recently reported for NH3 . Finally, water was found to replace preformed chelating copper nitrates and deplete NO+ (though with different kinetics) at both temperatures, while favouring the presence of monodentate ones.

Two series of Zn-ZSM-5 catalysts were prepared by ion exchanging two commercial zeolites with different Si/Al ratios (40 and 15) with increasing Zn loadings. The nature of the Zn sites in the zeolite was studied by spectroscopy using laboratory and synchrotron techniques. All the evidences suggest that catalytic activity is associated with [Zn(H2O)n(OH)]+ species located in the exchange positions of the materials with little or no contribution of ZnO or metallic Zn. The effect of Zn/Al ratio on their catalytic performance in methanol conversion to aromatics has been investigated. In all cases, higher Zn content causes an increase in the yield of aromatics while keeping the production of alkanes low. For similar Zn contents, high densities of Al sites favour the hydrogen transfer reactions and alkane formation whereas in samples with low Al contents, and thus higher Zn/Al ratio, the dehydrogenation reactions in which molecular hydrogen is released are favoured.

The interaction of tetrahedrally coordinated Ti3+ ions generated in the framework of TiAlPO-5 microporous materials with 12,13C2H4 leads to the formation of side-on η2 {Ti3+—C2H4} complexes with a unique 5-fold coordination of titanium, supported by four oxygen donor ligands of the framework. The detailed electronic and magnetic structure of this adduct is obtained by the combination of advanced EPR techniques (HYSCORE and SMART-HYSCORE) in conjunction with periodic and cluster model DFT calculations. The binding of C2H4 results from the σ overlap of low lying C2H4 filled π orbitals with the 3dz2 empty orbital of titanium, enhanced by a small contribution due the π overlap between the semioccupied 3dyz orbital of titanium and the empty π* orbital of ethylene. The spin density repartition over the ethylene molecule, obtained experimentally, allows probing directly the entity of the metal-to-substrate π*-back-donation, highlighting an asymmetry in the spin density delocalization. This interesting feature is...

This work deals with the characterization of ZnS NanoParticles (NP), prepared by precipitation employing thioacetamide as sulfur source at different reaction time length. The attention is focused on the modification induced on structural, surface and electronic properties of ZnS NP by post-synthesis treatments. These were aimed at removing from the samples surface adsorbed reactants, by washing or thermal treatments, both in air or vacuum. The effect of these parameters is followed by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform InfraRed (FTIR), gas-volumetric and ThermoGravimetric Analysis (TGA). Moreover, the effect of nanostructuration on the semiconducting material band gap is evaluated by Diffuse Reflectance UV-Vis (DR UV-Vis) spectroscopy. Density Functional Theory (DFT) calculations have been employed to clarify the role of the adsorbed reactants on the surface stability and to assess the relationship between particle size and band gap value.

Ordered mesoporous silica nanoparticles with pore diameter of 5 nm were synthesized by modification of the sol-gel synthesis method. Post-synthesis two-step grafting of thermoresponsive poly(N-isopropylacrylamide) inside the mesopores of the nanoparticles was carried out by distillation–precipitation polymerization of the methacryloxy-functionalized mesoporous nanoparticles with N-isopropylacrylamide monomer. A precise control on the quantity of the grafted polymer was achieved by changing the ratio of monomer to methacryloxy-functionalized nanoparticles. The polymer-grafted hybrid nanoparticles obtained were fully characterized by infrared spectroscopy, X-ray diffraction, dynamic light scattering, transmission electron microscopy, thermal, and gas-volumetric analyses, which clearly showed presence and thermoresponsive behavior of the polymer inside the mesopores with the preservation of the characteristic mesoporous structure of the nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd.

Hybrid-silica materials containing octyl, phenyl and urea-propyl functional groups were reported. These functionalized silicas were prepared by a via one-pot synthesis method through co-condensation of tetraethyl ortosilicate with organosilanes co-precursors. The obtained materials were analyzed by a number of techniques including scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction pattern and nitrogen sorption measurement. The main elements: morphology and surface properties of the final products that are basically dependent on the type and the quantity of functional-containing groups were fully discussed. The adsorption properties of the modified silicas were investigated against bilirubin in aqueous solution at pH 7.4, the effect of time was studied as well. The modified silicas showed a greatly increasing of adsorption capacity for bilirubin compared to pure amorphous silica. The results indicate that the type of functional-containing groups and surface properties affect the adsorption behavior. These materials show a potential application as effective adsorbents for bilirubin removal.

Amine-functionalized metal–organic frameworks EN-MIL-100(Cr) and MMEN-MIL-100(Cr) were prepared by grafting ethylenediamine and N,N′-dimethylethylenediamine molecules, respectively, on coordinatively unsaturated chromium(III) cations in MIL-100 metal–organic frameworks. Although amine grafting results in a decrease in the surface area and pore volume of the functionalized samples compared to those of the bare MIL-100(Cr), results showed that the incorporation of amine groups into the MIL-100 framework improved both carbon dioxide adsorption capacity and kinetics, especially in the case of ethylenediamine. Heats of carbon dioxide adsorption in EN-MIL-100(Cr) and MMEN-MIL-100(Cr) were about 80 kJ mol−1 at zero coverage, a value higher than that shown by MIL-100(Cr), which suggests chemisorption between CO2 and pendant amine groups. Measurement of CO2 adsorption–desorption cycles proved that functionalized materials show good regenerability and stability.

Copper–titania–zirconia mixed oxides with TiO 2 /ZrO 2 1:1 atomic ratio and copper content of 1, 3 and 5 wt% were prepared by one-step sol–gel method. X-ray diffraction and gas-volumetric analysis showed poor crystallinity and high specific surface area (around 250 m 2 /g) of the catalysts calcined at 400 °C. The nature of the copper species in the mixed oxides was characterized by temperature-programmed reduction in hydrogen (TPR), low-temperature electron paramagnetic resonance (EPR) and diffuse reflectance (DR) UV–Vis spectroscopies. These techniques suggested the presence of different copper species including distorted octahedral Cu 2+ ions (isolated or quasi-isolated) in the solid solution bulk, characterized by a TPR peak above 400 °C (labeled as T1), electronic d–d transitions around 800 nm and an anisotropic EPR signal with two hyperfine interactions in the g || region. The symmetry of this site changed from rhombic (S1) to axial (S3) while increasing copper loading. The inclusion of copper ions in the TiO 2 –ZrO 2 matrix was also testified by changes in the mixed-oxide edge position. Two families of supported copper oxide were found. CuO “bulk-like” showed relatively high reduction temperature (T2, around 250 °C), while highly dispersed CuO x nanoparticles/clusters resulted in TPR peaks around 170 and 200 °C (T4 and T3). These species were responsible for the UV–Vis adsorption above 400 nm and for the broad and asymmetric axial EPR signal with g || in the range from 2.14 to 2.29 (S2 and S2′). Finally, 2-propanol decomposition was employed as a test reaction to probe the catalyst's surface properties. The results suggested a marked effect of copper loading on the reactivity pattern, confirming the presence of CuO/CuO x particles on the surface of the TiO 2 –ZrO 2 support.

The small pore Cu-CHA zeolite is attracting increasing attention as a versatile platform to design novel single-site catalysts for deNOx applications and for the direct conversion of methane to methanol. Understanding at the atomic scale how the catalyst composition influences the Cu-species formed during thermal activation is a key step to unveil the relevant composition–activity relationships. Herein, we explore by in situ XAS the impact of Cu-CHA catalyst composition on temperature-dependent Cu-speciation and reducibility. Advanced multivariate analysis of in situ XANES in combination with DFT-assisted simulation of XANES spectra and multi-component EXAFS fits as well as in situ FTIR spectroscopy of adsorbed N2 allow us to obtain unprecedented quantitative structural information on the complex dynamics during the speciation of Cu-sites inside the framework of the CHA zeolite.

Ethylene oligomerization reaction on Ni-modified and unmodified ZSM-5 catalysts was studied at ambient pressure as a function of temperature by in situ FT-IR spectroscopy and mass spectrometry, focusing the attention on the formation of adsorbed species, which are likely to be responsible for the catalysts deactivation. The two catalysts show similar catalytic performance and selectivity, but different stability with time-on-stream, particularly in the 300–400 °C range. On both catalysts alkylated compounds and unsaturated carbocations were observed as stable adsorbed species up to 300 °C. The deactivation of the Ni-ZSM5 catalyst was related to the formation of a complex mixture of methylated polycondensed aromatic compounds (coke/coke precursors), which are not desorbed even by increasing the temperature up to 400 °C. In contrast, at 400 °C ethylene oligomerization on H-ZSM5 sample proceeds without deactivation due to the higher desorption rate of the surface species, which are mainly unsaturated carbocations with small amounts of methylated poly-condensed aromatics.

Cu-exchanged zeolites possess active sites that are able to cleave the C–H bond of methane at temperatures ≤200 °C, enabling its selective partial oxidation to methanol. Herein we explore this process over Cu-SSZ-13 materials. We combine activity tests and X-ray absorption spectroscopy (XAS) to thoroughly investigate the influence of reaction parameters and material elemental composition on the productivity and Cu speciation during the key process steps. We find that the CuII moieties responsible for the conversion are formed in the presence of O2 and that high temperature together with prolonged activation time increases the population of such active sites. We evidence a linear correlation between the reducibility of the materials and their methanol productivity. By optimizing the process conditions and material composition, we are able to reach a methanol productivity as high as 0.2 mol CH3OH/mol Cu (125 μmol/g), the highest value reported to date for Cu-SSZ-13. Our results clearly demonstrate that high populations of 2Al Z2CuII sites in 6r, favored at low values of both Si:Al and Cu:Al ratios, inhibit the material performance by being inactive for the conversion. Z[CuIIOH] complexes, although shown to be inactive, are identified as the precursors to the methane-converting active sites. By critical examination of the reported catalytic and spectroscopic evidence, we propose different possible routes for active-site formation. © 2017 American Chemical Society

Electron spin resonance and hyperfine sublevel correlation (HYSCORE) spectroscopy at X- and Q-band frequencies have been employed, in conjunction with X-ray absorption spectroscopy (XAS), to determine the geometric and electronic structure of Zn+ ions in H-ZSM-5 zeolite. Zn+ ions were generated by the direct exposure of dehydrated acid H-ZSM-5 to Zn vapors. The number of Zn+ ions is found to increase substantially upon UV irradiation. A single EPR active species is detected, indicating a single site of adsorption, characterized by the presence of an Al3+ site, as revealed by superhyperfine interactions. The full g (gx = 1.9951, gy = 1.9984, gz = 2.0015) and 27Al |A| (Ax = 2.8, Ay = 2.7, Az = 4.6) MHz tensors were resolved, allowing for a detailed description of the geometric and electronic structure of Zn+ ions stabilized in the cages of H-ZSM-5 zeolite. The dispersion and nuclearity of Zn species formed during the sublimation/irradiation process was assessed by means of XAS spectroscopy, which indicates ...

Carbon monoxide adsorption on nanosize ZnS has been investigated by FTIR spectroscopy and periodic DFT calculations. FTIR experiments show that CO adsorption on the zinc sulfide nanoparticles gives rise to a single main ν(CO) band indicating that the majority of the exposed sites are on the same surface. Computed adsorption energies (−0.244/–0.207 eV for the low and high coverage, respectively) and stretching frequencies (2182/2172 cm–1) of CO adsorbed at the most stable (110) ZnS surface are in excellent agreement with observations (ν(CO) = 2190/2168 cm–1). CO is weakly bound to the Zn2+ Lewis acid surface site mainly through electrostatic interaction and a small contribution from σ donation. The strength of surface Lewis sites in ZnS is lower with respect to ZnO.

[M]-CAL-2 (M = Mn, Co and Fe) are metallosilicoaluminophosphates ([M]-APSO) with chabazite-related structure, which are part of the CAL molecular sieves family. They were prepared with a recently developed synthesis based on the use of layered AlPO precursor. The used procedure allowed to obtain high loadings of metal ions and to control the morphology of the crystals. The materials were characterized by structural techniques such as X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetry (TGA), and spectroscopic techniques such as UV–Vis and Fourier transformed Infrared (FTIR) with particular attention to the study of their redox functionalities. The results show that [M]-CAL-2 crystals presented rhombohedra morphology and the particles sizes are dependent of the metal concentration in the precursor gel, in addition these particles have a lamellar memory originated from the layered AlPO precursor. The FTIR, UV–Vis and elemental results supported the presence of transition metal ions on the framework of the synthesized materials and allowed to envisage the dependency of the metal and silicon concentrations on a Lowenstein-like ruled substitution mechanism. Finally, the reversible redox behavior of the materials was studied by in situ UV–Vis-NIR spectroscopy. This aspect together with the already shown acidity of CAL samples allowed confirming the acid and redox bifunctionality of the obtained molecular sieves, which can thus be proposed for catalytic applications.

Mesoporous nanoparticles bearing different surface functionalizations were proposed as host carrier for the loading and stabilization of 5-aminolevulinic acid: unmodified mesoporous silica nanoparticles exposing native silanols and aminopropyltriethoxysilane-grafted mesoporous silica nanoparticles exposing amino groups. The stability of 5-aminolevulinic acid at different steps of drug loading was monitored via electronic and vibrational spectroscopies. Unmodified mesoporous nanoparticles were found to be a host system ensuring the stability of 5-aminolevulinic acid and its availability as protoporphyrin IX precursor, whilst silica surface exposing amino groups was found to strongly favour the dimerization of 5-aminolevulinic acid, leading to the formation of the derived compound pyrazine-2,5-dipropionic acid which is considered to be the major ALA degradation product in aerated solutions, which is no longer active as precursor of protoporphyrin IX. This phenomenon is interpreted in terms of the basic character of amino-modified silica.

Recently, mesoporous silica nanoparticles (MSNs) have emerged as promising drug delivery systems able to preserve the integrity of the carried substance and/or to selectively reach a target site; however, they have rarely been explored for skin application. In this study, thermoresponsive MSNs, designed to work at physiologic cutaneous temperature, are proposed as innovative topical carriers for quercetin (Q), a well-known antioxidant. The thermosensitive nanoparticles were prepared by functionalizing two different types of matrices, with pore size of 3.5nm (MSNsmall) and 5.0nm (MSNbig), carrying out a free radical copolymerization of N-isopropylacrylamide (NIPAM) and 3-(methacryloxypropyl)trimethoxysilane (MPS) inside the mesopores. The obtained copolymer-grafted MSNs (copoly-MSNs) were physico-chemically characterized and their biocompatibility was attested on a human keratinocyte cell line (HaCaT). The release profiles were assessed and the functional activity of Q, free or loaded, was evaluated in terms of antiradical and metal chelating activities. Ex vivo accumulation and permeation through porcine skin were also investigated. The characterization confirmed the copolymer functionalization of the MSNs. In addition, both the bare and functionalized silica matrices were found to be biocompatible. Among the copolymer-grafted complexes, Q/copoly-MSNbig exhibited more evident thermoresponsive behavior proving the potential of these thermosensitive systems for advanced dermal delivery.

In this paper, mesoporous silica nanoparticles (MSNs) were studied as vehicles for the delivery of the antitumoral drug gemcitabine (GEM) and of its 4-(N)-acyl derivatives, (4-(N)-valeroyl-(C5GEM), 4-(N)-lauroyl-(C12GEM) and 4-(N)-stearoyl-gemcitabine (C18GEM)). The loading of the GEM lipophilic prodrugs on MSNs was explored with the aim to obtain both a physical and a chemical protection of GEM from rapid plasmatic metabolization. For this purpose, MSNs as such or with grafted aminopropyl and carboxyethyl groups were prepared and characterized. Then, their different drug loading capacity in relation to the nature of the functional group was evaluated. In our experimental conditions, GEM was not loaded in any MSNs, while C12GEM was the most efficiently encapsulated and employed for further evaluation. The results showed that loading capacity increased with the presence of functional groups on the nanoparticles; similarly, the presence of functional groups on MSNs’ surface influenced the drug release profile. Finally, the cytotoxicity of the different preparations was evaluated and data showed that C12GEM loaded MSNs are less cytotoxic than the free drug with an activity that increased with the incubating time, indicating that all these systems are able to release the drug in a controlled manner. Altogether, the results demonstrate that these MSNs could be an interesting system for the delivery of anticancer drugs.

During the last decades, several studies have proposed manganese (Mn) complexes as alternative contrast agents for magnetic resonance imaging (MRI). With the nanotechnology surge in recent years, different types of Mn-based nanoparticles (Nps) have been developed. However, to design effective and safe administration procedures, preliminary studies on target cells, aimed at verifying their full biocompatibility and biodegradability, are mandatory. In this study, MnO containing-Nps encapsulated in a phospholipidic shell (PL-MnO Nps) were tested in cultured cells and flow cytometry; confocal and transmission electron microscopy were combined to understand the Nps uptake mechanism, intracellular distribution and degradation pathways, as well as possible organelle alterations. The results demonstrated that PL-MnO Nps undergo rapid and massive cell internalization, and persist free in the cytoplasm before undergoing lysosomal degradation without being cytotoxic or inducing subcellular damage. Based on the results with this cell model in vitro, PL-MnO Nps thus proved to be suitably biocompatible, and may be envisaged as very promising tools for therapeutic and diagnostic applications, as drug carriers or contrast agent for MRI.

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 vacuoles. No one of the tested nanocarriers was found to enter the nucleus. The exposure to the different nanocarriers did not increase cell death; only liposomes induced a reduction of cell population after long incubation times, probably due to cell overloading. No subcellular damage was observed to be induced by polymeric NPs and MSN, whereas transmission electron microscopy revealed cytoplasm alterations in liposome-treated cells. This important information on the structural and functional relationships between nanocarriers designed for drug delivery and cultured cells further proves the crucial role of microscopy techniques in nanotechnology.

MCM-41-like mesoporous silica nanoparticles (MSNs) grafted with a thermoresponsive copolymer of N-isopropylacrylamide were synthesized, fully characterized and tested to assess their efficiency as drug delivery systems. The hybrid nanoparticles were prepared by carrying out the optimized copolymer synthesis within the mesopores of MSNs after infiltration of monomers and initiator. Polymerization and grafting of the thermoresponsive copolymer occurred simultaneously by exploiting the reactive sites of the 3-methacryloxypropyltrimethoxysilane comonomer which carries a polymerizable group and alkoxysilane groups prone to condensation with surface silanols on silica. The grafted copolymer through its coil-to-globule transition acts as a gatekeeper for the temperature-controlled release of ibuprofen molecules loaded inside the pores. Significant difference in the quantitative release of ibuprofen was observed at 25 and 40 °C, which are below and above the lower critical solution temperature of the thermoresponsive copolymer. Importantly, the ordered mesoporous structure of the MSNs remained intact in all synthetic steps, loading of drug and during the in vitro release tests.

The equilibrium reaction between NO and Cu-nitrate, Cu(II)-NO3− + NO(g) ⇌ Cu(II)-NO2− + NO2(g), has been proposed to be a key step in the selective catalytic reduction of NO by ammonia (NH3-SCR) over Cu-CHA catalysts and points to the presence of Cu-nitrites. Whereas the formation of gaseous NO2 has been observed, a direct observation of Cu-nitrite groups under conditions relevant to NH3-SCR has been so far unsuccessful. In an effort to identify and characterize Cu-nitrites, the reaction between Cu-nitrates hosted in the CHA zeolite and NO is investigated by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) and X-ray absorption spectroscopy (XAS). We find that NO reacts with Cu-nitrates and that about half of the Cu-nitrate species are converted. After the reaction, the Cu(II) state is different from the original oxidized state. Analysis of XAS data indicates that the final state of the Cu-CHA catalyst is consistent with the partial conversion of the Cu-nitrate species to a bidentate Cu-nitrite configuration.

Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C−C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.