Adsorption of CO2 on Amine-Grafted Activated Carbon

Adsorption on amine-grafted materials may be a potentially attractive alternative to capturing CO2 from power plants. Activated Carbon (AC) has been proposed as a potential adsorbent due to its natural affinity for CO2 and to the possibility of tailoring textural properties and surface chemistry to enhance capacity and selectivity. An AC commercial sample was functionalized with monoethanolamine (MEA) in order to obtain nitrogen-enriched AC with two different loadings (ACN10 and ACN20). Samples characterization was carried out by nitrogen adsorption/desorption isotherms at 77 K, XPS, FTIR and adsorption microcalorimetry. CO2 equilibrium adsorption experiments were accomplished in a volumetric system in the pressure range of vacuum up to 10 bar, at 298 and 348 K. Impregnated activated carbon presented different chemical and textural characteristics with a significant reduction in the surface area, depending on the amine loading. A high adsorption capacity at room temperature and high pressure was observed for the pristine AC as compared to the modified samples. The reduction in surface area affected the adsorption capacity of CO2 at 298 and 348 K, except for adsorption on ACN10 at 348 K, which suggests the occurrence of chemisorption.Fil: Bezerra, Diôgo P.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Da Silva, Francisco W. M.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: de Moura, Pedro A. S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Vieira, Rodrigo S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Rodriguez Castellon, Enrique. Universidad de Malaga. Facultad de Ciencias; EspañaFil: de Azevedo, Diana C. S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; Brasi

The Carnegie Supernova Project I: photometry data release of low-redshift stripped-envelope supernovae

The first phase of the Carnegie Supernova Project (CSP-I) was a dedicated supernova follow-up program based at the Las Campanas Observatory that collected science data of young, low-redshift supernovae between 2004 and 2009. Presented in this paper is the CSP-I photometric data release of low-redshift stripped-envelope core-collapse supernovae. The data consist of optical (uBgVri) photometry of 34 objects, with a subset of 26 having near-infrared (YJH) photometry. Twenty objects have optical pre-maximum coverage with a subset of 12 beginning at least five days prior to the epoch of B-band maximum brightness. In the near-infrared, 17 objects have pre-maximum observations with a subset of 14 beginning at least five days prior to the epoch of J-band maximum brightness. Analysis of this photometric data release is presented in companion papers focusing on techniques to estimate host-galaxy extinction (Stritzinger et al., submitted) and the light-curve and progenitor star properties of the sample (Taddia et al., submitted). The analysis of an accompanying visual-wavelength spectroscopy sample of ~150 spectra will be the subject of a future paper.Comment: Updated a couple of small error

The Insulation of HVDC Extruded Cable System Joints. Part 1: Review of Materials, Design and Testing Procedures

This position paper by the DEIS HVDC Cable Systems Technical Committee provides a review of existing diagnostic electrical and dielectric techniques for testing the insulation of polymeric extruded HVDC cable joints in the present Part 1. Here, the state of the art on the insulation of HVDC extruded cable system joints is covered with reference to types, design and testing techniques. This helps to identify routine tests as the first target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers' practices for quality control of the insulation of accessories during routine tests and VHF/UHF wireless sensors as the best tool for performing such measurements on joints in the noisy factory environment. Thereby, a novel protocol for the measurement of partial discharges using AC voltages and VHF/UHF sensors, for quality control during routine tests on such joints, is derived in the next Part 2. This protocol is the main novelty of this investigation

The Insulation of HVDC Extruded Cable System Joints. Part 2: Proposal of a New AC Voltage PD Measurement Protocol for Quality Control during Routine Tests

The review of materials, design and testing of joints for HVDC extruded cable systems provided in previous Part 1 paved the way to this Part 2 position paper by the DEIS HVDC Cable Systems Technical Committee, whose aim is to remedy the scarcity of existing standardized tests on joints. After a sound analysis, here routine tests are identified as the first practical target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers’ experience for quality control of joints during routine tests and VHF/UHF wireless sensors as the best tool for such measurements in the noisy environment of factories. Thereby, a novel protocol for PD measurement using AC voltages and VHF/UHF electromagnetic sensors, for quality control during routine tests on HVDC extruded joints, is proposed

Investigating the Influence of Au Nanoparticles on Porous SiO2-WO3 and WO3 Methanol Transformation Catalysts

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021%2Facs.jpcc.6b08125Analyzing the structural and chemical properties of materials at the interface of metal nanoparticles and metal oxide supports is important for catalytic applications. Tungsten oxide (WO3) is a widely studied catalyst, but changing the catalytic reactivity at the surface of this oxide with metal nanoparticles is of interest. In this work, we sought to modify the redox properties of porous WO3 and SiO2 WO3 catalysts with sonochemically deposited gold nanoparticles (Au NPs) in order to access and study this reaction pathway. Characterization using powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES) confirmed that crystalline Au NPs with diameters of 5-12 nm were distributed throughout the catalysts. Temperature-programmed desorption (TPD) was used to probe the surface acidity of the catalysts. The physico-chemical characteristics of catalysts have been also discussed by considering the catalytic performance of these materials in the aerobic transformation of methanol. Catalysts containing nanocrystalline WO3 but no Au NPs displayed very high selectivity to DME (>60%) at all conversions with minor oxidation reactivity, which highlighted the acidic nature of these catalysts. No effect on the acidity of the catalysts was observed by TPD when Au NPs were loaded in the catalysts. The reducibility of the crystalline WO3 species, however, increased significantly due to the interaction with Au NPs, as observed by temperature-programmed reduction (TPR). In the gas-phase transformation of MeOH under aerobic conditions, catalysts modified with Au NPs showed greater activity compared to nonmodified catalysts. In addition, oxidation selectivity to products such as methyl formate as well as formaldehyde, dimethoxymethane, and carbon oxides became heavily favored with only minor dehydration selectivity. The redox properties of these WO3 catalysts could be tuned by changing the Au loading. More labile lattice oxygen and enhanced redox properties at the surface of WO3 modified with Au NPs clearly altered these traditional dehydration catalysts to potential oxidation catalysts. Thus, modification of WO3 with Au is an effective way to expand the MeOH transformation product distribution beyond DME to other useful, oxidized products not typically observed over pure WO3.The authors would like to thank the University of Vermont and the DGICYT in Spain (CTQ2015-68951-C3-1-R, CTQ2012-37925-C3-3-R, and SEV-2012-0267 Severo Ochoa Projects) for financial support and David M. Parker for assistance with catalyst synthesis.Depuccio, DP.; Ruiz-Rodríguez, L.; Rodriguez-Castellon, E.; Botella Asuncion, P.; López Nieto, JM.; Landry, CC. (2016). Investigating the Influence of Au Nanoparticles on Porous SiO2-WO3 and WO3 Methanol Transformation Catalysts. Journal of Physical Chemistry C. 120(49):27954-27963. https://doi.org/10.1021/acs.jpcc.6b08125S27954279631204

The Carnegie Supernova Project-I. Optical spectroscopy of stripped-envelope supernovae

We present 170 optical spectra of 35 low-redshift stripped-envelope core-collapse supernovae observed by the Carnegie Supernova Project-I between 2004 and 2009. The data extend from as early as -19 days (d) prior to the epoch of B-band maximum to +322 d, with the vast majority obtained during the so-called photospheric phase covering the weeks around peak luminosity. In addition to histogram plots characterizing the red-shift distribution, number of spectra per object, and the phase distribution of the sample, spectroscopic classification is also provided following standard criteria. The CSP-I spectra are electronically available and a detailed analysis of the data set is presented in a companion paper being the fifth and final paper of the seriesComment: Resubmitted to A&A after address referee's comments. Comments welcomed, and let us know if we missed to reference your paper

A High Pressure Operando Spectroscopy Examination of Bimetal Interactions in ‘Metal Efficient’ Palladium/In2O3/Al2O3 Catalysts for CO2 Hydrogenation

CO2 hydrogenation to methanol has the potential to serve as a sustainable route to a wide variety of hydrocarbons, fuels and plastics in the quest for net zero. Synergistic Pd-In2O3 (Palladium on Indium Oxide) catalysts show high CO2 conversion and methanol selectivity, enhancing methanol yield. The identity of the optimal active site for this reaction is unclear, either as a Pd−In alloy, proximate metals, or distinct sites. In this work, we demonstrate that metal-efficient Pd-In2O3 species dispersed on Al2O3 can match the performance of pure Pd-In2O3 systems. Further, we follow the evolution of both Pd and In sites, and surface species, under operando reaction conditions using X-ray Absorption Spectroscpy (XAS) and infrared (IR) spectroscopy. In doing so, we can determine both the nature of the active sites and the influence on the catalytic mechanism

Transition from Fireball to Poynting-flux-dominated Outflow in Three-Episode GRB 160625B

The ejecta composition is an open question in gamma-ray bursts (GRB) physics. Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis, suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the "Band" function, consistent with a synchrotron radiation origin and suggesting that the jet is Poynting-flux-dominated at the central engine and likely in the emission region as well. There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component suggesting a likely hybrid jet composition. Here we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-rays and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each "sub-burst" being $\sim$ 0.8 s, 35 s, and 212 s, respectively. Its high brightness (with isotropic peak luminosity L$_{\rm p, iso}\sim 4\times 10^{53}$ erg/s) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet.Comment: Revised version reflecting the referees' comments. 27 pages, 11 figures, 5 tables. The final edited version will appear in Nature Astronom

Carnegie Supernova Project II: The slowest rising Type Ia supernova LSQ14fmg and clues to the origin of super-Chandrasekhar/03fg-like events

The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties which may help to reveal the origin of the "super-Chandrasekhar" (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SN Ia, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At -23 rest-frame days relative to B-band maximum, LSQ14fmg is already brighter than $M_V$=-19 mag before host extinction correction. The observed color curves show a flat evolution from the earliest observation to approximately one week after maximum. The near-infrared light curves peak brighter than -20.5 mag in the J and H bands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At one month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized $^{56}Ni$. The excess flux matches the interaction with a typical superwind of an asymptotic giant branch (AGB) star in density structure, mass-loss rate, and duration. The rapid decline starting at around one month past B-band maximum may be an indication of rapid cooling by active carbon monoxide (CO) formation, which requires a low temperature and high density environment. These peculiarities point to an AGB progenitor near the end of its evolution and the core degenerate scenario as the likely explosion mechanism for LSQ14fmg.Comment: 22 pages, 15 figures, accepted for publication in Ap

The first 48: Discovery and progenitor constraints on the Type Ia supernova 2013gy

We present an early-phase $g$-band light curve and visual-wavelength spectra of the normal Type Ia supernova (SN) 2013gy. The light curve is constructed by determining the appropriate S-corrections to transform KAIT natural-system $B$- and $V$-band photometry and Carnegie Supernova Project natural-system $g$-band photometry to the Pan-STARRS1 $g$-band natural photometric system. A Markov Chain Monte Carlo calculation provides a best-fit single power-law function to the first ten epochs of photometry described by an exponent of $2.16^{+0.06}_{-0.06}$ and a time of first light of MJD 56629.4$^{+0.1}_{-0.1}$, which is $1.93^{+0.12}_{-0.13}$ days (i.e., $<48$~hr) before the discovery date (2013 December 4.84 UT) and $-19.10^{+0.12}_{-0.13}$ days before the time of $B$-band maximum (MJD 56648.5$\pm0.1$). The estimate of the time of first light is consistent with the explosion time inferred from the evolution of the Si II $\lambda$6355 Doppler velocity. Furthermore, discovery photometry and previous nondetection limits enable us to constrain the companion radius down to $R_c \leq 4\,R_{\odot}$. In addition to our early-time constraints, we use a deep +235 day nebular-phase spectrum from Magellan/IMACS to place a stripped H-mass limit of $< 0.018\,M_{\odot}$. Combined, these limits effectively rule out H-rich nondegenerate companions