Study of the Synthetic Approach Influence in Ni/CeO2-Based Catalysts for Methane Dry Reforming

This study focuses on the synthetic approach influence in morphostructural features and catalytic performances for Ni/CeO2 catalysts. Incipient wetness impregnation, coprecipitation and nitrate combustion were studied as catalyst preparation approaches, and the materials were then tested at 700 C for methane dry reforming (MDR). The morphostructural properties of the materials were deeply studied using several techniques, such as temperature programmed reduction (TPR), to investigate reducibility and support-metal interaction, N2 physisorption to evaluate the porosity and the surface area, scanning electron microscopy (SEM) and X-ray diffraction (XRD) to estimate Ni dispersion, and temperature programmed oxidation (TPO) to identify the type and amount of coke formed on catalysts’ surface after reaction. From the data obtained, coprecipitation turned out to be the most suitable technique for this application because this catalyst was able to reach 70% of CO2 conversion and 30% methane conversion, with an H2 yield of 15% and 30% yield of CO at the end of the 30 h test. Moreover, it was also the catalyst with the highest metal dispersion, the strongest interaction with the support, and the lowest coke deposition

The Highly Energetic Expansion of SN2010bh Associated with GRB 100316D

We present the spectroscopic and photometric evolution of the nearby (z = 0.059) spectroscopically confirmed type Ic supernova, SN 2010bh, associated with the soft, long-duration gamma-ray burst (X-ray flash) GRB 100316D. Intensive follow-up observations of SN 2010bh were performed at the ESO Very Large Telescope (VLT) using the X-shooter and FORS2 instruments. Owing to the detailed temporal coverage and the extended wavelength range (3000--24800 A), we obtained an unprecedentedly rich spectral sequence among the hypernovae, making SN 2010bh one of the best studied representatives of this SN class. We find that SN 2010bh has a more rapid rise to maximum brightness (8.0 +/- 1.0 rest-frame days) and a fainter absolute peak luminosity (L_bol~3e42 erg/s) than previously observed SN events associated with GRBs. Our estimate of the ejected (56)Ni mass is 0.12 +/- 0.02 Msun. From the broad spectral features we measure expansion velocities up to 47,000 km/s, higher than those of SNe 1998bw (GRB 980425) and 2006aj (GRB 060218). Helium absorption lines He I lambda5876 and He I 1.083 microm, blueshifted by ~20,000--30,000 km/s and ~28,000--38,000 km/s, respectively, may be present in the optical spectra. However, the lack of coverage of the He I 2.058 microm line prevents us from confirming such identifications. The nebular spectrum, taken at ~186 days after the explosion, shows a broad but faint [O I] emission at 6340 A. The light-curve shape and photospheric expansion velocities of SN 2010bh suggest that we witnessed a highly energetic explosion with a small ejected mass (E_k ~ 1e52 erg and M_ej ~ 3 Msun). The observed properties of SN 2010bh further extend the heterogeneity of the class of GRB supernovae.Comment: 37 pages and 12 figures (one-column pre-print format), accepted for publication in Ap

Blazars as Ultra-High-Energy Cosmic-Ray Sources: Implications for TeV Gamma-Ray Observations

The spectra of BL Lac objects and Fanaroff-Riley I radio galaxies are commonly explained by the one-zone leptonic synchrotron self-Compton (SSC) model. Spectral modeling of correlated multiwavelength data gives the comoving magnetic field strength, the bulk outflow Lorentz factor and the emission region size. Assuming the validity of the SSC model, the Hillas condition shows that only in rare cases can such sources accelerate protons to much above 10^19 eV, so > 10^20 eV ultra-high-energy cosmic rays (UHECRs) are likely to be heavy ions if powered by this type of radio-loud active galactic nuclei (AGN). Survival of nuclei is shown to be possible in TeV BL Lacs and misaligned counterparts with weak photohadronic emissions. Another signature of hadronic production is intergalactic UHECR-induced cascade emission, which is an alternative explanation of the TeV spectra of some extreme non-variable blazars such as 1ES 0229+200 or 1ES 1101-232. We study this kind of cascade signal, taking into account effects of the structured extragalactic magnetic fields in which the sources should be embedded. We demonstrate the importance of cosmic-ray deflections on the gamma-ray flux, and show that required absolute cosmic-ray luminosities are larger than the average UHECR luminosity inferred from UHECR observations and can even be comparable to the Eddington luminosity of supermassive black holes. Future TeV gamma-ray observations using the Cherenkov Telescope Array and the High Altitude Water Cherenkov detector array can test for UHECR acceleration by observing >25 TeV photons from relatively low-redshift sources such as 1ES 0229+200, and > TeV photons from more distant radio-loud AGN.Comment: 14 pages, 9 figures, 2 tables, accepted for publication in ApJ, references and discussions adde

Vanadium: an efficient promoter for Ni/Al2O3 based catalysts in Methane Dry Reforming

Methane dry reforming (MDR) is a promising process for syngas production through the valorization of two of the main Greenhouse gases (GHGs): CO2 and CH4 [1]. As a matter of fact, the exploitation GHGs for the production of added value chemical could be one of the possible solutions for atmospheric carbon dioxide reduction. The catalyst plays a key role in this reaction as it should encourage syngas formation by limiting coke deactivation. In this work the attention was focusses on the effects of vanadium promoter in nickel-based catalysts [2]. In particular, the prepared Ni-V/Al2O3, and Ni-V-Ca/Al2O3 were compared to the bare Ni/Al2O3. The fresh and spent catalysts were characterized via N2-physisorption, TPR, XRD, TPO, TEM and SEM techniques to understand the morpho-physical features of the materials and to identify the causes of catalysts deactivation. The catalysts were tested for MDR at the temperature of 650 °C for 100h. The best results were achieved by Ni-V-Ca/Al2O3 with a stable 45% of hydrogen yield, 81% conversion of CH4 and 88% conversion of CO2. The catalytic activity can be well explained by the characterization performed on the catalysts: vanadium and calcium are capable to ensure good metal dispersion and stronger interaction with the support which is mandatory for the stability of the catalyst towards coking and deactivation. As a matter of fact, from spent catalyst is possible to observe that vanadium introduction favors the formation of only superficial carbon nanotubes which do not cover Ni active site. This allows the catalyst to retain its activity for long time

Vanadium: an efficient promoter for Ni/Al2O3 based catalysts in Methane Dry Reforming

Methane dry reforming (MDR) is a promising process for syngas production. In this work the attention was focusses on the effects of vanadium promoter in nickel-based catalysts. The best results were achieved by Ni-V-Ca/Al2O3. Vanadium and calcium are capable to ensure good metal dispersion and stronger interaction with the suppor

Perovskites and exsolution: new catalysts for Methane Dry Reforming reaction

Methane Dry Reforming could be a solution to exploit two powerful GHGs, methane and carbon dioxide, to produce hydrogen in a more sustainable way, but the catalytic system suffer of a fast deactivation. This due to sinterization and coke depostion. To minimize these effects, perovskites was studied. A perovskite structure was synthesized to obtain La0.8Ce0.2Fe0.7Ni0.3O3 and then it was treated in a reducing environment at high temperature (800°C) to carry out what is called "exsolution". This phenomenon should exstract part of the elements from perovskite structure, forming metal nanoparticles in surface. This is the active phase, that should be better anchored to support, better dispersed and so be more resistant against deactivation. The study is focused on investigating the best exsolution conditions to obtain the best active phase for Methane Dry Reforming catalytic purposes

Perovskites and exsolution: new catalysts for Methane Dry Reforming reaction

Methane Dry Reforming could be a solution to exploit two powerful GHGs, methane and carbon dioxide, to produce hydrogen in a more sustainable way, but the catalytic system suffer of a fast deactivation. This due to sinterization and coke depostion. To minimize these effects, perovskites was studied. A perovskite structure was synthesized to obtain La0.8Ce0.2Fe0.7Ni0.3O3 and then it was treated in a reducing environment at high temperature (800°C) to carry out what is called "exsolution". This phenomenon should exstract part of the elements from perovskite structure, forming metal nanoparticles in surface. This is the active phase, that should be better anchored to support, better dispersed and so be more resistant against deactivation. The study is focused on investigating the best exsolution conditions to obtain the best active phase for Methane Dry Reforming catalytic purposes

Vanadium doped Ni/Al2O3: Efficient and coke resistant catalysts for methane dry reforming

The effects of vanadium promotion on γ-alumina supported nickel catalysts were investigated for Methane Dry reforming (MDR). Three samples were compared: bare Ni/Al2O3 as reference, Ni-V/Al2O3, and Ni-V-Ca/Al2O3 to evaluate whether the introduction of these additional doping agents can further improve the activity and the stability of the catalyst. The catalysts were synthetized via incipient wetness impregnation and tested in MDR at 650 °C, first with a reagents ratio CH4:CO2:He= 1:1:18 and then CH4:CO2:He= 1:1:8. Fresh and spent catalysts were studied by different techniques, such as N2 physisorption, TPR, XRD, DRUV–VIS, SEM-EDX, O2 chemisorption and TPO. In diluted gases conditions, the introduction of vanadium is crucial to hinder catalyst deactivation by coke deposition. In particular, the formation of nanotubes was reduced, with an increase in hydrogen yield. When coupled with calcium, selectivity toward hydrogen/syngas production was improved. Under concentrated gases was highlighted how vanadium is fundamental for a higher activity, with an increase of 30% and 15% in CH4 and CO2 conversions, if compared with the non-doped catalyst

Cataract standard set for outcome measures: An Italian tertiary referral centre experience

Purpose: Implementation of the International Consortium for Health Outcomes Measurements (ICHOM) standard for cataract surgery into clinical practice at an Italian tertiary referral centre. Methods: Prospective, observational, descriptive study consisting of the registry and analysis of cataract surgeries performed during a 6-month enrolment period at the University Eye Clinic of Trieste, Trieste, Italy. Outcomes were recorded and analysed according to the ICHOM Cataract Standard Set version 2.0.1. Records included clinician-reported outcome measures (CROMs) – visual outcome and complications – and patient-reported outcome measures (PROMs) – self-assessed vision with the Catquest-9SF questionnaire. Correlations between PROMs and CROMs were evaluated. A multiple linear regression was used for predicting the change in PROMs with surgery. Results: A total of 218 eyes (of 218 patients) were analysed. Postoperative corrected distance visual acuity (CDVA) was ⩾0.3 in 89.0% (194/218) of eyes. There was a statistically significant improvement of the post-operative Catquest-9SF global average score. (p 75 years old, and preoperative CDVA. Conclusions: Cataract surgery improves the functional vision, with some factors limiting the outcomes such as comorbidities. Self-perceived improvement in intermediate vision significantly influenced the improvement in self-assessed vision.This study has been supported by an unrestricted grant from Johnson & Johnson Vision to obtain the access to the ICHOM standard set for cataract surgery

Study of the Synthetic Approach Influence in Ni/CeO2-Based Catalysts for Methane Dry Reforming

This study focuses on the synthetic approach influence in morphostructural features and catalytic performances for Ni/CeO2 catalysts. Incipient wetness impregnation, coprecipitation and nitrate combustion were studied as catalyst preparation approaches, and the materials were then tested at 700 °C for methane dry reforming (MDR). The morphostructural properties of the materials were deeply studied using several techniques, such as temperature programmed reduction (TPR), to investigate reducibility and support-metal interaction, N2 physisorption to evaluate the porosity and the surface area, scanning electron microscopy (SEM) and X-ray diffraction (XRD) to estimate Ni dispersion, and temperature programmed oxidation (TPO) to identify the type and amount of coke formed on catalysts’ surface after reaction. From the data obtained, coprecipitation turned out to be the most suitable technique for this application because this catalyst was able to reach 70% of CO2 conversion and 30% methane conversion, with an H2 yield of 15% and 30% yield of CO at the end of the 30 h test. Moreover, it was also the catalyst with the highest metal dispersion, the strongest interaction with the support, and the lowest coke deposition