CNR Institute on Membrane Technology

Padova, Italy

CNR Institute on Membrane Technology

Padova, Italy
Time filter
Source Type

Frezzato D.,University of Padua | Saielli G.,CNR Institute on Membrane Technology
Journal of Physical Chemistry B | Year: 2016

We have investigated the structural and dynamic properties of Xe dissolved in the ionic liquid crystal (ILC) phase of 1-hexadecyl-3-methylimidazolium nitrate using classical molecular dynamics (MD) simulations. Xe is found to be preferentially dissolved within the hydrophobic environment of the alkyl chains rather than in the ionic layers of the smectic phase. The structural parameters and the estimated local diffusion coefficients concerning the short-time motion of Xe are used to parametrize a theoretical model based on the Smoluchowski equation for the macroscopic dynamics across the smectic layers, a feature which cannot be directly obtained from the relatively short MD simulations. This protocol represents an efficient combination of computational and theoretical tools to obtain information on slow processes concerning the permeability and diffusivity of the xenon in smectic ILCs. © 2016 American Chemical Society.

Bagno A.,University of Padua | Saielli G.,CNR Institute on Membrane Technology
Chemistry - A European Journal | Year: 2012

Shift change: Relativistic ZORA DFT calculations highlight the various factors (solvent effect, spin-orbit coupling, number and type of metal centres) responsible of the extraordinarily large deshielding of xenon encapsulated in a metallated cryptophane (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Saielli G.,CNR Institute on Membrane Technology
Journal of Physical Chemistry A | Year: 2010

We have employed computational protocols to determine the differential solvation free energy in water of oxonium and ammonium ions. We have focused our analysis on pairs of onium ions having the same hydrocarbon content and substitutional pattern (HCSP pairs). In agreement with previous suggestions (Taft, R. W.; Wolf. J. F.; Beauchamp, J. L.; Scorrano, G.; Arnett, E. M. J. Am. Chem. Soc. 1978, 100, 1240), we found that cavitation and van der Waals terms do not contribute to the differential solvation free energy. Moreover, we observe that oxonium ions are more strongly solvated than the analogous ammonium ions even though the former ones have fewer H-bond donor sites. The performance of two different continuum solvation models, PCM and SMD, is discussed. © 2010 American Chemical Society.

Pingitore V.,University of Calabria | Gugliuzza A.,CNR Institute on Membrane Technology
Journal of Physical Chemistry C | Year: 2013

Semiconductor hybrid structures are achieved by interfacing single-walled carbon nanotubes (CNTs) with microstructured porous membranes. Interconnectivity and interplay of nanotubes are achieved by the assistance of adaptive polymers on 3D ordered honeycomb membranes. The buildup of semiconductor interfaces is based on the nanoassembly concept, which includes (a) self-assembly of sacrificial water droplets for tailoring 3D ordered polymeric platforms; (b) directed assembly of carbon nanotubes by sequential layer-by-layer (LBL) deposition; and (c) improvement of the electrical contact between nanotubes and stabilization of the organic-inorganic interface by pH-directed forces. Unprecedented better-quality charge-transfer pathways are achieved by making a large number of connections between nanotubes rather than increasing the adsorption of conductive inorganic materials onto the membrane platforms. Electrical current transfer is generated in hybrid interfaces, wherein fine conductivity function (σ 102 S/m) is associated with high-defined porous structure, through a rationalization of the role of intermolecular forces in the assembly process. © 2013 American Chemical Society.

Sartorel A.,CNR Institute on Membrane Technology | Carraro M.,CNR Institute on Membrane Technology | Toma F.M.,University of Trieste | Prato M.,University of Trieste | Bonchio M.,CNR Institute on Membrane Technology
Energy and Environmental Science | Year: 2012

Water oxidation is the crucial stage in the chemical and molecular sequence of photosynthesis, designed by Nature to convert solar light into chemical energy. The artificial "off-leaf" transposition is a major goal of energy research, aiming at the continuous production of hydrogen as a solar fuel, through the photo-catalytic splitting of water. Success in this task primarily depends on the interplay of light-activated multi-electron oxidation and reduction cycles and on the invention of stable and robust water oxidation catalysts, liberating oxygen with fast rates, high quantum yield, and long-term activity. A promising perspective is herein envisaged in the molecular design of functional metal-oxide cores and composite nano-materials. © The Royal Society of Chemistry 2012.

Saielli G.,CNR Institute on Membrane Technology
Journal of Physical Chemistry B | Year: 2016

We present a fully atomistic molecular dynamics simulation of the smectic phase of the ionic liquid crystal (ILC) 1-hexadecyl-3-methylimidazolium nitrate, [C16MIm][NO3]. We have characterized the structure of the phase by means of a set of radial distribution functions resolved along the director and in the plane of the smectic layers. The results obtained allow us to discuss the similarities in the microscopic structure of ionic liquids (ILs) and ILCs. In addition to this, we have calculated the orientational order parameters, S, of the methylene groups of the alkyl chain and compared them with the results obtained for phospholipidic membranes from 2H NMR experiments. We also discuss the orientational order parameters of the imidazolium ring. Finally, we analyze the distribution of voids in the ILC phase. We have found that voids of considerable volume to host a nonpolar gas, e.g. xenon, are localized in the hydrophobic layers and almost absent in the ionic layers. © 2016 American Chemical Society.

Sartorel A.,CNR Institute on Membrane Technology | Bonchio M.,CNR Institute on Membrane Technology | Campagna S.,Messina University | Scandola F.,University of Ferrara
Chemical Society Reviews | Year: 2013

Among molecular water oxidation catalysts (WOCs), those featuring a reactive set of four multi-redox transition metals can leverage an extraordinary interplay of electronic and structural properties. These are of particular interest, owing to their close structural, and possibly functional, relationship to the oxygen evolving complex of natural photosynthesis. In this review, special attention is given to two classes of tetrametallic molecular WOCs: (i) M4O4 cubane-type structures stabilized by simple organic ligands, and (ii) systems in which a tetranuclear metal core is stabilized by coordination of two polyoxometalate (POM) ligands. Recent work in this rapidly evolving field is reviewed, with particular emphasis on photocatalytic aspects. Special attention is given to studies addressing the mechanistic complexity of these systems, sometimes overlooked in the rush for oxygen evolving performance. The complementary role of molecular WOCs and their relationship with bulk oxides and heterogeneous catalysis are discussed. © 2013 The Royal Society of Chemistry.

Iulianelli A.,CNR Institute on Membrane Technology | Basile A.,CNR Institute on Membrane Technology
International Journal of Hydrogen Energy | Year: 2010

A bio-ethanol mixture was used for carrying out the ethanol steam reforming (ESR) reaction in a Pd-Ag dense membrane reactor (MR) in order to produce a CO-free hydrogen stream. The MR was packed with a commercial Co-based catalyst and the experimental tests were performed between 250 and 400 °C, at 1.5 bar of reaction pressure and in both co-current and counter-current flow configurations. Experimental results in terms of ethanol conversion, products selectivities and CO-free hydrogen yield are reported as well as a discussion on the CO-free hydrogen stream recovered in the permeate side of the MR (directly suitable for feeding a PEM fuel cell system) is also presented. Moreover, a comparison with a traditional reactor (TR) working at the same MR operating conditions is realized, pointing out that the MR is able to give ethanol conversions higher than the TR in all the experimental tests realized in this work. © 2009 Professor T. Nejat Veziroglu.

Iulianelli A.,CNR Institute on Membrane Technology | Ribeirinha P.,University of Porto | Mendes A.,University of Porto | Basile A.,CNR Institute on Membrane Technology
Renewable and Sustainable Energy Reviews | Year: 2014

In the recent years, hydrogen has gained a considerable interest as an energy carrier useful for various applications and, particularly, for polymer electrolyte membrane fuel cells (PEMFCs) supply. Nevertheless, PEMFCs require high purity hydrogen as a feeding fuel, which shows some limitations regarding storage and transportation. Therefore, to overcome these problems, the in situ hydrogen generation has made attractive both alcohols and hydrocarbons steam reforming reaction. Among other fuels, methanol is an interesting hydrogen source because it is liquid at ambient conditions, possesses relatively high H/C ratio, low reforming temperature (200-300 C) and it is also producible from biomass. Meanwhile, there is a comprehensive literature about inorganic membrane reactors utilization for hydrogen generation via methanol steam reforming reaction. This review illustrates the earlier state of the art from an experimental point of view about hydrogen production from methanol reforming performed in both conventional and membrane reactors. Furthermore, a short overview about methanol reforming catalysts as well as a discussion on the impact of methanol steam reforming process via inorganic membrane reactors to produce hydrogen for PEMFCs supply is given. © 2013 Elsevier Ltd.

We report on the thermal behaviour of a model system based on a coarse-grained force field (CG-FF) developed for ionic liquids here extended to the description of the ionic liquid crystal 1-hexadecyl-3-methylimidazolium nitrate. The phase diagram has been investigated as a function of the temperature in the NPT ensemble. We have identified three distinct phases, a crystal phase, the smectic A phase and the isotropic liquid phase. The various phases have been characterized by several pair distribution functions, density profiles and order parameters. A comparison is made with the experimental data available and suggestions on how to re-parameterise the CG-FF in order to achieve a better accuracy for the description of ionic mesophases are presented. On the other hand the results reported in this work demonstrate that the model potential is sufficiently accurate, at a qualitative level, to obtain useful insights into the relation between structural parameters, such as anion and cation core size, chain lengths and others, and the thermal range of stability of the ionic mesophases. © The Royal Society of Chemistry 2012.

Loading CNR Institute on Membrane Technology collaborators
Loading CNR Institute on Membrane Technology collaborators