A5007528857- Catalysis and Hydrodesulfurization Studies
- Catalytic Processes in Materials Science
- Nanomaterials for catalytic reactions
- Advanced X-ray Imaging Techniques
- Adaptive optics and wavefront sensing
- X-ray Spectroscopy and Fluorescence Analysis
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Electrocatalysts for Energy Conversion
- Advanced Chemical Physics Studies
- Radioactivity and Radon Measurements
- Particle Detector Development and Performance
- Catalysts for Methane Reforming
- solar cell performance optimization
- Atmospheric Ozone and Climate
- Metal Extraction and Bioleaching
- Advanced materials and composites
- Solar and Space Plasma Dynamics
- Thermal and Kinetic Analysis
- Optical Systems and Laser Technology
- Advanced Thermoelectric Materials and Devices
- Metallurgical and Alloy Processes
- Advanced Materials Characterization Techniques
- Superconducting and THz Device Technology
- Silicon and Solar Cell Technologies
Osservatorio Astronomico di Palermo
2004-2024
National Institute for Astrophysics
2004-2024
University of Palermo
2018
Haldor Topsoe (Denmark)
1976-1986
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExtended x-ray absorption fine structure study of the cobalt-molybdenum hydrodesulfurization catalystsBjerne S. Clausen, Henrik Topsoe, Roberto Candia, Jorgen Villadsen, Bruno Lengeler, Jens Als-Nielsen, and Finn ChristensenCite this: J. Phys. Chem. 1981, 85, 25, 3868–3872Publication Date (Print):December 1, 1981Publication History Published online1 May 2002Published inissue 1 December...
Abstract The changes, which take place in the structural and catalytic properties of Co‐Mo/Al 2 O 3 catalysts sulfided at different temperatures, have been elucidated by means high resolution electron microscopy (HREM), ir, XRD, chemisorption oxygen. It was observed that temperature sulfiding induces a growth Co‐Mo‐S crystals are MoS ‐like with Co occupying edge positions. For all catalysts, found to be most important feature determining HDS activity it occur activity, can explained terms...
Abstract The present article will discuss the recent developments which have taken place with “Co‐Mo‐S model”. Some new results also be presented to elucidate some of controversies existed in literature. Co‐Mo‐S model, was originally based on Mössbauer emission spectroscopy (MES) measurements, has now been confirmed and further developed by use extended x‐ray absorption fine structure (EXAFS), infrared (ir), photoelectron (XPS), high resolution analytical electron microscopy (HREM AEM),...
Abstract Mössbauer spectroscopy is one of the new tools which recently have been applied to study HDS catalysts. The technique has several unique features make it especially useful in such catalysts and given answers some much debated problems, studies yielded insight into, for example. origin promotion, (ii) reason catalytic synergy, (iii) nature active phase, (iv) observed similarities between unsupported supported catalysts, (v) loading support effects. article will review available...
Abstract Unsupported Co‐Mo catalysts were prepared by two different methods:by the co‐maceration (CM) method and a new homogeneous sulfide precipitation (HSP) method. Structural examinations means of XRD Mössbauer Emission Spectroscopy (HES) show that CM contain several phases with Co 9 S 8 being dominant cobalt containing phase. On other hand, HSP are shown to only one CO phase within an extended range Co/Mo atomic ratios this is Co‐Mo‐S Like in case supported catalysts, be responsible for...
Abstract Information regarding the structure of cobalt containing phases in calcined as well sulfided Co‐Mo/Al 2 O 3 catalysts is obtained by analyzing extended x‐ray absorption fine (EXAFS) above Co K‐edge and comparing these results with those for model compounds. For studied, show no evidence any well‐ordered compounds which have been proposed to be present such catalysts. In catalyst atoms are observed quite disordered surroundings distinct backscattering only from nearest neighbor...
Little is known about the effects of X-rays in interstellar ices. To understand sulfur depletion dense clouds and presence S2 comets, we simulated experimentally soft X-ray processing (0.3 keV) H2S ice for first time. Experiments were performed under ultrahigh vacuum conditions at 8 K using infrared quadrupole mass spectrometry to monitor solid gas phases, respectively. A UV irradiation experiment a similar dose was made comparison. After irradiation, an absorption appears near 4.0 μm which...
There is an increasing evidence for the existence of large organic molecules in interstellar and circumstellar medium. Very few among such species are readily formed conventional gas-phase chemistry under typical conditions clouds. Attention has therefore focused on ices as a potential source these relatively complex species. Laboratory experiments show that irradiation ice analogues by fast particles or ultraviolet radiation can induce significant chemical complexity. However, stars sources...
Abstract In the present paper, we will discuss recent results which show that catalytically active Co‐Mo‐S or Ni‐Mo‐S structures consist of Co Ni atoms at edges MoS 2 . The evidence has been observed by ir studies NO adsorption and analytical electron microscopy (AEM) investigation alumina supported unsupported Co‐Mo Ni‐Mo hydrodesulfurization catalysts. These have also extended to catalysts sulfided elevated temperatures. By combining AEM with from Mössbauer emission spectroscopy (MES)...
Abstract An important issue in the chemistry of interstellar ices is role dust materials. In this work, we study effect an amorphous water-rich magnesium silicate deposited onto ZnSe windows on chemical evolution ultraviolet-irradiated methanol ices. For comparison, also irradiate similar bare windows. Silicates are produced at relatively low temperatures exploiting a sol–gel technique. The composition synthesized material reflects forsterite stoichiometry. Si–OH groups and carbonates...
The X-ray Integral Field Unit (X-IFU) is one of the two instruments Athena astrophysics space mission approved by ESA in Cosmic Vision 2015-2025 Science Programme. X-IFU consists a large array transition edge sensor micro-calorimeters that will operate at ~100 mK inside sophisticated cryostat. A set thin filters, highly transparent to X-rays, be mounted on opening windows cryostat thermal shields order attenuate IR radiative load, radio frequency electromagnetic interferences, and protect...
X-ray detectors for space astrophysics missions are susceptible to noise caused by photons with energies outside the operating energy range; this reason, efficient external optical blocking filters required shield detector from out-of-band radiation. These play a crucial role in meeting scientific requirements of detectors, and their proper operation over life mission is essential success experimental activity. We studied thin sandwich membranes made silicon nitride aluminum as high-energy...
We studied the effects of soft X-rays radiation on free and clay (montmorillonite, kaolinite) adsorbed DNA. The DNA samples were exposed to 1.49, 4.51 8.04 keV for exposure times ranging from 2 min up 16 h. biological transformation technique was used estimate damage molecules. Free are differently affected by X-rays. former is damaged level depends energy dose rather than hardness radiation. not doses 5.8×10 4 erg. Clays materials could have protected building blocks life primordial Earth...
The X-ray Astronomy Calibration and Testing (XACT) facility of the Instituto Nazionale di Astrofisica (INAF) at Osservatorio Astronomico Palermo has recently undergone a major upgrade with design construction 35 meter long vacuum beam-line operating in soft X-rays (0.1-20 keV) addition new hardware to meet requirements for testing calibration next generation missions. We report on present configuration briefly survey range its applications.
The Wide Field Imager (WFI) is one of the two instruments ATHENA astrophysics space mission approved by ESA as second large in Cosmic Vision 2015-2025 Science Programme. WFI, based on a array depleted field effect transistors (DEPFET), will provide imaging 0.2-15 keV band over 40'x40' view, simultaneously with spectrally and time resolved photon counting. WFI detector also sensitive to UV/Vis photons, an electron-hole pair production efficiency UV/VIS larger than that for X-ray photons....
In the framework of FAE "Fotovoltaico ad Alta Efficienza" ("High Efficiency Photovoltaic") Research Project (PO FESR Sicilia 2007/2013 4.1.1.1), we have performed electrical and optical characterizations commercial InGaP/InGaAs/Ge triple-junction solar cells (1 cm2) mounted on a prototype HCPV module, installed in Palermo (Italy). This system uses reflective optics based rectangular off-axis parabolic mirror with aperture 45×45 cm2 leading to geometrical concentration ratio 2025. this study,...
Adjustable mirrors equipped with piezo actuators are commonly used at synchrotron and free-electron laser (FEL) beamlines, in order to optimize their focusing properties sometimes shape the intensity distribution of focal spot desired profile. Unlike them, X-ray for astronomy much thinner enable nesting reduce areal mass, application acting normally surface appears more difficult. There remains possibility correct deformations using thin patches that exert a tangential strain on rear side...