With the rapid increasing of the available number of novel porous materials, a straightforward and low-cost testing methodology to assess those suitable for near ambient temperature hydrogen storage ...applications is needed. In this work, we developed a new assessment methodology to quickly identify those porous materials potentially suitable for near ambient temperature hydrogen storage applications. We introduced the usable capacity map showing why the absolute adsorption capacity at the temperature of 77 K is not a good indicator to compare the material's storage performance. In fact, some porous material that shows low usable capacity at 77 K appear to be better adsorbent at a higher temperature. Moreover, we demonstrated that using quick cyclic adsorption isotherm or TDS is possible to easily individuate those materials that are the most suitable for near ambient temperature applications. Therefore, as a general result, we showed that among the three commercial activated carbon, used here as case study, the one with the higher content of ultramicroporosity is the most promising because the optimum operating temperature shifts towards ambient temperature.
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•Low-cost assessment methodology for hydrogen storage on porous materials.•Quick identification of materials with a large concentration of high ΔHads sites.•Usable capacity maps analysis.•Cyclic adsorption and TDS measurement.•Evaluation of the optimum operating temperature.
The adsorption and the thermal desorption of hydrogen in as-made and surface-modified silicalite-1 (MFI) loose crystals has been studied to shed light on the relation between the outer surface ...barrier and the transport of mass through it. The four different surface modifications can be probed by the change in the contact angle of water, but do not produce any apparent change in the morphology and the structure of the crystals. The H2 adsorption isotherms in a Sievert's-type apparatus at 77 K and up to 8 MPa on the pristine and the modified silicalite-1 samples are almost overlapping, showing that the modifications involve the external surface of the samples. However the diffusion coefficients of H2, as derived from the sorption kinetics, evidence different sorption rates of H2 into the different silicalite-1 samples. In particular the unmodified silicalite-1 sample presents the lowest diffusion coefficient and yields the highest H2 desorption temperature in Thermal Desorption Spectra acquired at 0.03 K/s. The observed phenomena have been attributed to the surface silanols on the outer surface of the as-made silicalite-1 crystals, which are either eliminated or greatly reduced in number by the modifying agents. Polar and hydrophilic silanol groups bind frozen water molecules on the outer surface of as-made crystals which hinder the diffusion of hydrogen, and interact more strongly with the H2 molecules. This provides sorption sites with higher potential energy barriers, and at the same time physically obstructs the pore entrances of the molecular sieve. The surface modification of porous fillers is of interest for the manufacture of mixed matrix membranes, for the improvement of the performance of pressure swing adsorption processes, and for gas storage applications.
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•A surface barrier for the transport of H2 at 77 K is evidenced on silicalite-1.•Surface modification of MFI crystals speeds up H2 sorption and desorption.•Surface silanols trap moisture and enhance the surface barrier.•Pore obstruction and stronger sorption may explain the enhancement of the barrier.•Surface modification can tailor the transport properties of fillers and adsorbents.
A full-size prototype of a Micromegas precision tracking chamber for the upgrade of the ATLAS detector at the LHC Collider has been built between October 2015 and April 2016. This paper describes in ...detail the procedures followed in the construction of the components of the chamber in various INFN laboratories and the final assembly in the Laboratori Nazionali di Frascati (LNF). In addition, the results of the chamber exposure to a particle beam at SPS/H8 at CERN in June 2016 are presented. The performances obtained in the construction and the results of the test beam are compared with the requirements set in order to sustain the high radiation levels expected during the data-taking of the LHC in the next years.
The electromagnetic performance of the RD52 fiber calorimeter Akchurin, N.; Bedeschi, F.; Cardini, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2014, Letnik:
735
Journal Article
Recenzirano
Odprti dostop
The RD52 calorimeter is an instrument intended to detect both electromagnetic and hadronic showers, as well as muons, using the dual-readout principle. Scintillation and Cherenkov light provide the ...two signals which, in combination, allow for superior hadronic performance. In this paper, we report on the electromagnetic performance of this instrument, and compare this performance with that of other calorimeters that were constructed with similar goals in mind.
•Tungsten trioxide films deposited by sol–gel route on ITO–glass substrates.•Formation of rod-like and platelet shaped nanocrystalline structures.•Mixed WO3 and Na2WO4 phases. Different evolution of ...bulk and surface structure.
The electronic, morphological and structural properties of WO3 thin films, synthesized via a sol–gel route and deposited on ITO/glass substrates by spin-coating, were analyzed as a function of annealing temperature (100–700°C range) by Scanning Electron Microscopy, Atomic Force Microscopy, micro-Raman spectroscopy, X-ray Diffraction and Photoelectron Spectroscopy. We have found evidence of two competing processes when the film is annealed at high temperatures (600–700°C): a structural phase transition from amorphous to crystalline WO3 and a temperature-activated diffusion of sodium ions, from the substrate into the WO3 film, which induces the formation of sodium tungstate. The surface of the films was found to be oxygen deficient after deposition but reverted to fully oxidized WO3 after high temperature annealing in air. The annealing also induced a restructuring of the films with formation of nano-crystalline aggregates. The influence of film thickness on these processes was also investigated.
The RD52 dual-readout calorimeter is a longitudinally unsegmented instrument intended for the detection of both electromagnetically and hadronically interacting particles with unprecedented ...precision. In this paper, the identification of the showering particles and, in particular, the identification of electrons and gamma s with this instrument are investigated. The techniques used for this purpose include differences in the shower development observed with scintillation light and Cherenkov radiation, the radial shower profile of the particles and the time structure (including the starting point) of the calorimeter signals. It turns out that, at 60 GeV, electrons can be correctly identified in 99.8% of the cases, by means of criteria that eliminate 99.8% of the hadrons.
•Poly(ε-caprolactone) as a renewable candidate for Carbon Capture and Utilization.•Fully reversible carbon dioxide storage at ambient condition.•Green, sustainable and very cheap material.
...Poly(ε-caprolactone) (PCL) is a cheap and sustainable polymer with long-term degradation (3–4 years) and low temperature transition (Tm=∼60°C). We report on the investigation of PCL as a valid green candidate for Carbon Capture and Utilization (CCU). Studies were carried out by two complementary tools: a Sievert-type volumetric apparatus, to thoroughly analyse the CO2 adsorption/desorption process inside the polymer, and Nuclear Magnetic Resonance (NMR) spectroscopy for a deeper study of the molecular dynamics and confinement effects through 13C – pulsed field gradient (PFG) method (self-diffusion measurements), relaxation times (T1) and spectral analysis. The morphology of the solid-state PCL was also investigated by Scanning Electron Microscopy (SEM). The effects of both the physical state and the adsorption process conditions on the PCL's CO2 sorption capabilities were investigated as well as those concerning the cyclic life and the regeneration process. We find that two kind of adsorption sites are present in PCL matrix. Furthermore, PCL show a remarkable and complete thermoreversibility of the CO2 adsorption process, a key condition in view of possible applications in this field.
The RD52 calorimeter uses the dual-readout principle to detect both electromagnetic and hadronic showers, as well as muons. Scintillation and Cherenkov light provide the two signals which, in ...combination, allow for superior hadronic performance. In this paper, we report on detailed, GEANT4 based Monte Carlo simulations of the performance of this instrument. The results of these simulations are compared in great detail to measurements that have been carried out and published by the DREAM Collaboration. This comparison makes it possible to understand subtle details of the shower development in this unusual particle detector. It also allows for predictions of the improvement in the performance that may be expected for larger detectors of this type. These studies also revealed some inadequacies in the GEANT4 simulation packages, especially for hadronic showers, but also for the Cherenkov signals from electromagnetic showers.
In this study, the storage capacities of new-concept metal organic frameworks (MOFs) hybrids towards CO2 and CH4 were investigated. Three benzene-1,3,5-tricarboxylic acid (BTC)-based MOFs with ...different metallic centers (Cu, Al, Fe) and their hybrids embedding a new-concept graphene related material (graphene like (GL) layers) at low concentration (5 wt%) were produced. Adsorption/desorption tests have been carried out at room temperature (RT) up to 5.0 MPa depending on the gas specimen and the adsorption data have been modeled in accordance with the Töth model. All the sorbents exhibited a higher affinity toward CO2 over CH4. The MOF/GL hybrids and the pristine MOFs exhibited reversible adsorption process with and/or without regeneration through thermal treatment. In particular, the Cu- and Fe-based MOFs fully recovered their CO2 storage capacity without any thermal treatment. MOF/GL hybrids exhibited a quicker saturation for all the analyzed gases. The MOF/GL hybrids and the pristine MOFs presented similar interaction with the tested gases: the occurrence of strong interactions (nearing the magnitude of chemisorption) is evidenced for Cu-based and Al-based materials, while physisorption phenomena characterized the Fe-based materials. The selectivity towards CO2 over CH4 exhibited by MOF/GL hybrids appeared interesting (over 65 in the case of the Cu-based hybrid), even if great advantages over that of the pristine MOF at high pressure were not detected for all the investigated materials. Finally, it is worth noting the enhanced CO2 and CH4 adsorptions exhibited at low-pressure (<0.2 MPa) by the Al-based hybrid.
•A new class of hybrid BTC-based MOFs was produced and tested as gas sorbents.•The GL incorporation at 5 wt% does not drastically affect MOFs textural properties.•Instauration of favorable, reversible and strong interactions between CO2 and MOFs.•No obvious advantage of MOFs hybridization with GL in the high-pressure range.•Enhanced CO2 and CH4 adsorptions at low-pressure (<0.2 MPa) in Al-MIL96/GL.
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