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International audience; HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT’s diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT’s unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, and provide a summary of the instrument’s design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.

Effective formulation of new gasoline or diesel fuels for internal combustion engines would benefit from the development of reliable models for predicting key fuel properties based on a set of mole...

The Field Wet Resistance Test (FWRT) is a procedure used to evaluate the integrity of a PV array's insulation. A field version of the Wet Insulation Integrity test in IEEE 1262 and IEC 60146. this test evaluates wiring, connectors, and junction boxes in addition to module encapsulation. A decade of experience at PVUSA shows that arrays nearly always pass easily or fail miserably. The test deftly locates nicked wire insulation, loose junction box covers, screw driver-penetrated module backsheets, inadequate connector seals, hairline cracks in module junction boxes, and other potentially unsafe and unreliable conditions. These mechanical problems are typically indicated as a short or near short to ground in the presence of an aqueous surfactant. Even without these problems, there are often large variations— factors of 2 to 10— in readings throughout the array. In this paper, we investigate a number of variables that affect the measured wet resistance of a PV array. Sorting through these variables will lead to more accurate measurement and diagnosis of impending failures. Results indicate glass temperature and settling time have a much greater influence than previously anticipated. Conversely, surfactant concentration and array voltage have very little effect.

We survey research using neural sequence-to-sequence models as compu-tational models of morphological learning and learnability. We discusstheir use in determining the predictability of inflectional exponents, inmaking predictions about language acquisition and in modeling languagechange. Finally, we make some proposals for future work in these areas.

Warm (250–450 °C) cleanup of coal- or biomass-derived syngas requires sorbents and catalysts to protect downstream conversions. We report first a sequential ZnO bed operation in which the capacity is optimized for bulk desulfurization at 450 °C, while subsequent removal of sulfur to parts-per-billion levels can be accomplished at a lower temperature of approximately 300 °C. At this temperature, gaseous sulfur (H2S and COS) could be adsorbed equally well using ZnO, both with and without the presence of H2O in the feed, suggesting direct absorption of COS can occur. Following five sulfidation and regeneration cycles, the bulk desulfurization bed lost about a third of its initial sulfur capacity; however, sorbent capacity stabilized. A bench-scale process consisting of five unit operations is described for the cleanup of a several contaminants in addition to sulfur. Syngas cleanup was demonstrated through successful long-term performance of a poison-sensitive Cu-based water-gas shift catalyst placed downstre...

AOLI (Adaptive Optics Lucky Imager) is a state-of-art instrument that combines adaptive optics (AO) and lucky imaging (LI) with the objective of obtaining diffraction limited images in visible wavelength at mid- and big-size ground-based telescopes. The key innovation of AOLI is the development and use of the new TP3-WFS (Two Pupil Plane Positions Wavefront Sensor). The TP3-WFS, working in visible band, represents an advance over classical wavefront sensors such as the Shack-Hartmann WFS (SH-WFS) because it can theoretically use fainter natural reference stars, which would ultimately provide better sky coverages to AO instruments using this newer sensor. This paper describes the software, algorithms and procedures that enabled AOLI to become the first astronomical instrument performing real-time adaptive optics corrections in a telescope with this new type of WFS, including the first control-related results at the William Herschel Telescope (WHT)., Comment: 15 pages, 18 figures, Accepted 2017 January 27

We describe our exploratory system for the shallow surface realization task, which combines morphological inflection using character sequence-to-sequence models with a baseline linearizer that implements a tree-to-tree model using sequence-to-sequence models on serialized trees. Results for morphological inflection were competitive across languages. Due to time constraints, we could only submit complete results (including linearization) for English. Preliminary linearization results were decent, with a small benefit from reranking to prefer valid output trees, but inadequate control over the words in the output led to poor quality on longer sentences.

We report high spatial resolution i' band imaging of the multiple T Tauri system LkH$\alpha$ 262/LkH$\alpha$ 263 obtained during the first commissioning period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel Telescope, using its Lucky Imaging mode. AOLI images have provided photometry for each of the two components LkH$\alpha$ 263 A and B (0.41 arcsec separation) and marginal evidence for an unresolved binary or a disc in LkH$\alpha$ 262. The AOLI data combined with previously available and newly obtained optical and infrared imaging show that the three components of LkH$\alpha$ 263 are co-moving, that there is orbital motion in the AB pair, and, remarkably, that LkH$\alpha$ 262-263 is a common proper motion system with less than 1 mas/yr relative motion. We argue that this is a likely five-component gravitationally bounded system. According to BT-settl models the mass of each of the five components is close to 0.4 M$_{\odot}$ and the age is in the range 1-2 Myr. The presence of discs in some of the components offers an interesting opportunity to investigate the formation and evolution of discs in the early stages of multiple very low-mass systems. In particular, we provide tentative evidence that the disc in 263C could be coplanar with the orbit of 263AB.

This study presents an investigation into the steam reforming of hydrocarbons from biomass gasifier-derived syngas over MgAl 2 O 4 -supported transition metals (Ni, Rh, Ir, Ru, Pt, and Pd) and novel bimetallic IrNi catalysts. Using a model syngas consisting of H 2 , CO, CO 2 , CH 4 , C 2 H 4 , and H 2 O, Ir and Rh catalysts were found to be the most stable catalysts (at 850 °C, 1 bar, 114,000 h −1 ). When benzene and naphthalene are added to the feed (as a tar simulant) stability is affected by both tar concentration and type of tar. Catalytic deactivation, caused primarily by coking can be minimized by operating at a high reaction temperature (e.g., 850 °C). In addition, promoting Ni catalyst with Ir significantly enhances stability. By using bimetallic formulations of Ir and Ni (0.5–5.0% Ir, 15%Ni), nickel sintering during the reaction is reduced. Surprisingly, IrNi catalysts also offer more stability than catalysts with Ir particles alone. In agreement with theoretical calculations, small Ir° clusters (∼2–3 atoms) supported on large Ni° particles (≥5 nm) present more resistance to coking than either small Ir° clusters or Ni° particles alone. Hence, superior stability of the bimetallic catalysts results from both resistance to coking and a decrease in nickel sintering. Minimal loss of activity of 12% for TOS = 80 h is demonstrated for a bimetallic catalyst with optimal concentrations of 2.5% Ir and 15% Ni. Both monometallic Ir and Ni catalysts suffer substantial loss of activity (i.e., ≥40% loss, TOS = 80 h) under comparable conditions.

NaNO3 and other alkali nitrate salts, which are present in the molten state during use, have been described as facilitators or catalysts for CO2 absorption by both MgO and MgO-containing double salts. Although MgO exhibits a high capacity (exceeding 70 wt %), its regenerability in multicycle tests shows a significant loss of capacity with cycle number prior to lining out. On the other hand, the MgO–Na2CO3 double salt shows a lower (∼16 wt %) but stable capacity over multiple cycles under pressure swing operation. The purpose of this paper is to elaborate on the concept of molten salts as catalysts for CO2 absorption by MgO, and extend these observations to the MgO-containing double salt oxides. We will show that the phenomena involved with CO2 absorption by MgO and MgO-based double salts are similar and general, but with some important differences. This paper focuses on the following key concepts: (i) identification of conditions that favor or disfavor participation of isolated MgO during double salt abso...

When interpreting questions in a virtual patient dialogue system one must inevitably tackle the challenge of a long tail of relatively infrequently asked questions. To make progress on this challenge, we investigate the use of paraphrasing for data augmentation and neural memory-based classification, finding that the two methods work best in combination. In particular, we find that the neural memory-based approach not only outperforms a straight CNN classifier on low frequency questions, but also takes better advantage of the augmented data created by paraphrasing, together yielding a nearly 10% absolute improvement in accuracy on the least frequently asked questions.

In this paper, we report the fundamental surface properties of Pt/C and Pt–Re/C catalysts and their correlation with catalytic performance in steam reforming of glycerol. We found that the addition of Re increases the catalytic activity, H 2 /CO x ratio, and CO 2 selectivity. N 2 physisorption, CO chemisorption, and attenuated total reflectance infrared (ATR-IR), Raman, and X-ray absorption spectroscopy (XAS) with in situ capabilities were employed to provide insight into the roles of Re. Using ATR-IR, we show that CO adsorption on reduced Pt–Re/C is stronger than on Pt/C. However, CO desorption from Pt–Re/C is much facilitated compared with that from Pt/C after steam pretreatment, which is more representative of the steam reforming conditions. In situ Raman and XAS studies suggest that oxidized rhenium species are formed in steam environments on the Pt–Re/C catalyst surface. The spillover of CO from neighboring Pt to such oxidized rhenium is likely the reason for the facile desorption of CO, which could further react to form CO 2 . Such facile CO desorption leads to enhanced glycerol steam reforming and water-gas shift activities over the Pt–Re/C catalyst.

This paper describes our “breaker” submission to the 2017 EMNLP “Build It Break It” shared task on sentiment analysis. In order to cause the “builder” systems to make incorrect predictions, we edited items in the blind test data according to linguistically interpretable strategies that allow us to assess the ease with which the builder systems learn various components of linguistic structure. On the whole, our submitted pairs break all systems at a high rate (72.6%), indicating that sentiment analysis as an NLP task may still have a lot of ground to cover. Of the breaker strategies that we consider, we find our semantic and pragmatic manipulations to pose the most substantial difficulties for the builder systems.

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of $\lesssim$30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution ($R \sim 50$) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the $Y$, $J$, and $H$ bands ($\sim$952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with ${\chi}^2$ minimization suggesting a best fit for spectral type T7.0$\pm$1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature $T_{\text{eff}}=741 \pm 25$ K and surface gravity $\log g = 4.3 \pm 0.5$ dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date., Comment: Accepted for publication in ApJ, 13 pages, 11 figures v2 updated with minor edits from corrected proofs

Syngas, a mixture of CO and H2 (CO/H2), is a key platform for the utilization of nonpetroleum carbon resources such as natural gas or shale gas and coal. Syngas can also be produced from renewable carbon feedstocks such as biomass and even CO2. A variety of products including hydrocarbons and oxygenates, which can be fuels and chemicals, may be produced from syngas. The catalytic transformation of syngas into value-added products is the core of C1 chemistry. This review highlights advances in the past decade in catalytic conversions of syngas into hydrocarbons with an emphasis on selective formations of C5 + hydrocarbons, which are mainly used as liquid fuels, and lower (C2–C4) olefins, key building-block chemicals. Since CO2 is also contained in syngas from some resources, the catalytic hydrogenation of CO2 to hydrocarbons will also be briefly described. Fischer–Tropsch synthesis is a well-established process for syngas to hydrocarbons, but many fundamental aspects remain unclear because of the complexity of the reaction. The products of Fischer–Tropsch synthesis usually follow the Anderson–Schulz–Flory distribution, which is very wide and is nonselective for a target product such as liquid fuels or lower olefins. This article highlights recent advances in understanding the active phase of Fischer–Tropsch catalysts and in designing efficient catalysts using new materials. Furthermore, this article pays particular attention to the breakthrough in the selectivity control, which is the most important challenge for scientific research in syngas chemistry. Besides insights into various factors determining product selectivity as well as activity, we will also discuss emerging methodologies and strategies for the selective conversion of syngas into a specific range of hydrocarbons.

A composite Pd/ZnO/Al2O3-HZSM-5 (Si/Al=40) catalytic system was evaluated for the synthesis of gasoline-range hydrocarbons directly from synthesis gas. Bifunctional catalyst comprising PdZn metal and acid sites present the required catalytically active sites necessary for the methanol synthesis, methanol dehydration, and methanol-to-gasoline reactions. This system provides a unique catalytic pathway for the production of liquid hydrocarbons directly from syngas. However, selectivity control is difficult and poses many challenges. The composite catalytic system was evaluated under various process conditions. Investigated were the effects of temperature (310-375oC), pressure (300-1000 psig), time-on-stream (50 hrs), and gas-hour space velocity (740-2970 hr-1), using a H2/CO molar syngas ratio of 2.0. By operating at the lower end of the temperature range investigated, liquid hydrocarbon formation was favored, as was decreased amounts of undesirable light hydrocarbons. However, lower operating temperatures also facilitated undesirable CO2 formation via the water-gas shift reaction. Higher operating pressures slightly favored liquid synthesis. Operating at relatively low pressures (e.g. 300 psig) was made possible, whereas for methanol synthesis alone higher pressure are usually required to achieve similar conversion levels (e.g. 1000 psig). Thermodynamic constraints on methanol synthesis are eased by pushing the equilibrium through hydrocarbon formation. Catalytic performance was also evaluated by altering Pdmore » and Zn composition of the Pd/ZnO/Al2O3 catalyst. Of the catalysts and conditions tested, selectivity toward liquid hydrocarbon was highest when using a 5% Pd metal loading and Pd/Zn molar ratio of 0.25 and mixed with HZMS-5, operating at 310oC and 300 psig, CO conversion was 43 % and selectivity (carbon weight basis) to hydrocarbons was 49 wt. %. Of the hydrocarbon fraction, 44wt. % was in the C5-C12 liquid product range and consisted primarily of aromatic polymethylbenzenes. However, as syngas conversion increases with increasing temperature, selectivity to liquid product diminished. This is attributed, in large part, to increased saturation of the olefinic intermediates over PdZn metal sites. Under all the conditions and catalysts evaluated in this study, generating liquid product in high yield was challenging (

The CO2 capture properties of M2CO3 (M = Na, K)-promoted and CaCO3-promoted MgO sorbents are investigated by first-principles density functional theory complemented with lattice phonon calculations. The calculated thermodynamic properties indicate that by forming double salts (M2Mg(CO3)2 and CaMg(CO3)2), compared to pure MgO, the maximum allowable CO2 capture temperatures of the M2CO3- and CaCO3- modified MgO sorbents are shifted to higher temperature ranges. Under pre-combustion conditions with PCO2 = 10 bar, the Na2CO3-promoted and CaCO3-promoted MgO sorbents can capture CO2 at temperatures as high as 915 K and 740 K respectively. While under post-combustion conditions with PCO2 = 0.1 bar, their maximum allowable CO2 capture temperatures are 710 K and 600 K respectively. However, when adding K2CO3 into MgO, under both pre- and post-combustion conditions, its maximum CO2 capture temperatures only increased about 10 K relative to pure MgO. These results indicate that by mixing another solid into MgO, it is possible to shift its CO2 capture temperature to fit practical industrial needs.

Systems comprising multiple sorbent and catalytic beds have been developed for the warm cleanup of coal- and biomass-derived syngas. Tailored specifically for biomass application, the process described here consists of six primary unit operations: (1) a Na2CO3 bed for HCl removal, (2) two regenerable ZnO beds in parallel for bulk H2S removal, (3) a ZnO bed for H2S polishing, (4) a NiCu/SBA-16 sorbent for trace metal (e.g., AsH3) removal, (5) a steam reforming catalyst bed for tars and light hydrocarbon reformation and NH3 decomposition, and (6) a Cu-based LT-WGS catalyst bed. Simulated biomass-derived syngas containing possible inorganic contaminants (H2S, AsH3, HCl, and NH3) and hydrocarbons (methane, ethylene, benzene, and naphthalene) was used to demonstrate process effectiveness. The efficiency of the process was demonstrated for a period of 175 h, during which time no signs of deactivation were observed. However, postrun analysis revealed that small levels of sulfur slipped through the sorbent bed tr...

Absorption and desorption of carbon dioxide on Na 2 CO 3 -promoted MgO have been studied at temperatures compatible with warm gas cleanup (300–470 °C) from a pre-combustion syngas. The absorbents are synthesized through the formation and activation of the precipitate resulting from the addition of sodium carbonate to an aqueous solution of magnesium nitrate. The absorbent, which comprises MgO, Na 2 CO 3 and residual NaNO 3 after activation, forms the double salt Na 2 Mg(CO 3 ) 2 on exposure to CO 2 . The thermodynamic properties of the double salt, obtained through computational calculation, predict that the preferred temperature range for absorption of CO 2 with the double salt is significantly higher compared with MgO. Faster CO 2 uptake can be achieved as a result of this higher temperature absorption window. Absorption tests indicate that the double salt absorbent as prepared has a capacity toward CO 2 of 15 wt.% (3.4 mmol CO 2 /g absorbent) and can be easily regenerated through both pressure swing and temperature swing absorption in multiple-cycle tests. Thermodynamic calculations also predict an important effect of CO 2 partial pressure on the absorption capacity in the warm temperature range. The impurity phase, NaNO 3 , is identified as a key component in facilitating CO 2 absorption by these materials. The reason for reported difficulties in reproducing the performance of these materials can be traced to specific details of the synthesis method, which are reviewed in some detail.

This work examines CRF-based sequence alignment models for learning natural language morphology. Although these systems have performed well for a limited number of languages, this work, as part of the SIGMORPHON 2016 shared task, specifically sets out to determine whether these models handle non-concatenative morphology as well as previous work might suggest. Results, however, indicate a strong preference for simpler, concatenative morphological systems.

The combination of Lucky Imaging with a low order adaptive optics system was demonstrated very successfully on the Palomar 5m telescope nearly 10 years ago. It is still the only system to give such high-resolution images in the visible or near infrared on ground-based telescope of faint astronomical targets. The development of AOLI for deployment initially on the WHT 4.2 m telescope in La Palma, Canary Islands, will be described in this paper. In particular, we will look at the design and status of our low order curvature wavefront sensor which has been somewhat simplified to make it more efficient, ensuring coverage over much of the sky with natural guide stars as reference object. AOLI uses optically butted electron multiplying CCDs to give an imaging array of 2000 x 2000 pixels., Comment: 7 pages, 5 figures, SPIE conference 9908, Edinburgh,June 2016. arXiv admin note: substantial text overlap with arXiv:1408.0117, arXiv:1207.4065

The current generation of precision radial velocity (RV) spectrographs are seeing-limited instruments. In order to achieve high spectral resolution on 8m class telescopes, these spectrographs require large optics and in turn, large instrument volumes. Achieving milli-Kelvin thermal stability for these systems is challenging but is vital in order to obtain a single measurement RV precision of better than 1m/s. This precision is crucial to study Earth-like exoplanets within the habitable zone. iLocater is a next generation RV instrument being developed for the Large Binocular Telescope. Unlike seeing-limited RV instruments, iLocater uses adaptive optics (AO) to inject a diffraction-limited beam into single-mode fibers. These fibers illuminate the instrument spectrograph, facilitating a diffraction-limited design and a small instrument volume compared to present-day instruments. This enables intrinsic instrument stability and facilitates precision thermal control. We present the current design of the iLocater cryostat which houses the instrument spectrograph and the strategy for its thermal control. The spectrograph is situated within a pair of radiation shields mounted inside an MLI lined vacuum chamber. The outer radiation shield is actively controlled to maintain instrument stability at the sub-mK level and minimize effects of thermal changes from the external environment. An inner shield passively dampens any residual temperature fluctuations and is radiatively coupled to the optical board. To provide intrinsic stability, the optical board and optic mounts will be made from Invar and cooled to 58K to benefit from a zero coefficient of thermal expansion (CTE) value at this temperature. Combined, the small footprint of the instrument spectrograph, the use of Invar, and precision thermal control will allow long-term sub-milliKelvin stability to facilitate precision RV measurements., Comment: 10 pages, 7 figures

In situ X-ray absorption spectroscopy (XAS) results on correlating the Pt local coordination and electronic structure with the Pt/C catalyst activity and selectivity during aqueous reforming of glycerol at different pH are reported. The results show that both low and high pH favor C–O cleavage over that of C–C. However, the selectivity toward C–O bond cleavage was higher under the acidic conditions. XANES measurements under reaction conditions showed that low pH increased the Pt electron density while the effect of basic conditions was minimal. ΔXANES was used to estimate the coverage of adsorbates under reaction conditions and the results suggest a change in the adsorbates coverage by the acidic conditions, resulting in higher electron density on Pt.

After the 9.0 magnitude earthquake and subsequent massive tsunami on 11 March 2011 in Japan, several reactors at the Fukushima Daiichi Nuclear Power Plant suffered severe damage. There was immediate participation of U.S. Navy vessels and other United States Department of Defense (DoD) teams that were already in the area at the time of the disaster or arrived shortly thereafter. The correct determination of occupational dose equivalent requires estimation of the background dose component measured by control dosimeters, which is subsequently subtracted from the total dose equivalent measured by personal dosimeters. The purpose of the control dosimeters is to determine the amount of radiation dose equivalent that has accumulated on the dosimeter from background or other non-occupational sources while they are in transit or being stored. Given the release of radioactive material and potential exposure to radiation from the Fukushima Daiichi Nuclear Power Plant and the process by which the U.S. Navy calculates occupational exposure to ionizing radiation, analysis of pre- and post-event control dosimeters is warranted. Several hundred historical dose records from the Naval Dosimetry Center (NDC) database were analyzed and compared with the post-accident dose equivalent data of control dosimeters. As result, it was shown that the dose contribution of the radiation and released radiological materials from the Fukushima nuclear accident to background radiation doses is less than 0.375 μSv d for shallow and deep photon dose equivalent. There is no measurable effect on neutron background exposure. The latter has at least two important conclusions. First, the NDC can use doses measured by control dosimeters at issuing sites in Japan for determination of personnel dose equivalents; second, the dose data from control dosimeters prior to and after the Fukushima accident may be used to assist in dose reconstruction of non-radiological (non-badged) personnel at these locations.

The catalytic roles of Co0 and Co2+ during steam reforming of ethanol were investigated over Co/MgO catalysts. Catalysts with different Co0/(Co0+Co2+) fraction were prepared through calcination and/or reduction at different temperatures, and the Co0 fraction was quantified by temperature programmed reduction (TPR) and in situ X-ray photoelectron spectroscopy (XPS). Higher temperature calcination of Co/MgO allowed us to prepare catalysts with more nonreducible Co2+ incorporated in the MgO lattice, while lower calcination temperatures allowed for the preparation of catalysts with higher Co0/(Co0+Co2+) fractions. The catalytic tests on Co0, nonreducible Co2+, and reducible Co2+ indicated that Co0 is much more active than either reducible or nonreducible Co2+ for C−C cleavage and water gas shift reaction. In addition, catalysts with a higher Co0 surface fraction exhibited a lower selectivity to CH4.

Nickel-based catalysts have been widely tested for reforming undesired tar and methane from hot biomass-derived syngas. However, nickel catalysts readily deactivate through the adsorption of sulfur compounds in the syngas. We report a new regeneration process that can effectively regenerate sulfur-poisoned Ni reforming catalysts. This process consists of four sequential treatments: (1) controlled oxidation at 750 °C in 1% O2, (2) decomposition at 900 °C in inert gas, (3) reduction at 900 °C in 2% H2, and (4) reaction at 900 °C under reforming condition. This 4-step regeneration process might have advantages over the conventional steam regeneration process.

It is known that sulfur oxides contribute significantly and deleteriously to the overall performance of lean-burn diesel engine after-treatment systems, especially in the case of NOx traps. A silica-supported silver-based, fast regenerable SO2 absorbent has been developed and will be described. Over a temperature range of 300–550 °C, it absorbs SO2 present in a simulated exhaust gas during the lean cycles, and can be fully regenerated by short rich gas cycles at the same temperature. The preferred silica support is fumed silica. The thermal instability of Ag2O under fuel-lean conditions at 230 °C and above makes it possible to rapidly regenerate the sulfur-loaded absorbent during the fuel-rich cycle due to the lack of a requirement to simultaneously reduce Ag2O to Ag. Ag particles can also effectively oxidize SO2 to SO3, facilitating the formation of Ag2SO4 and requiring no additional oxidation catalysts. This absorbent shows great potential to work under the same lean-rich cycling conditions as those imposed on the NOx traps, and thus can protect the downstream particulate filter and the NOx trap from sulfur poisoning.

Hydrogen production from the aqueous phase reforming of glycerol over several 3%Pt-Re/C catalysts (1-4.5% Re) has been studied in the absence and presence of base, and the results compared with a Re-free 3%Pt/C catalyst. Although the Pt/C catalyst is very selective toward the production of hydrogen, catalytic activity is low. Addition of Re significantly increases the conversion of glycerol, at some loss of hydrogen selectivity to light hydrocarbons and water-soluble oxygenates. Addition of 1%KOH to the feedstock increases the selectivity of the Pt-Re/C catalysts toward hydrogen, but selectivity toward aqueous phase oxygenates also increases except for 3%Pt-3%Re/C, where it remains constant. The increase in hydrogen selectivity with base addition arises primarily from reducing the selectivity toward methane and higher alkanes, products that consume H2. For comparison, KOH addition to the glycerol feed with the Re-free 3%Pt/C catalyst provides an increase in glycerol conversion but results in a decline in both H2 and alkanes relative to aqueous phase oxygenates. This indicates that alternative pathways have been enabled by base addition. The highest hydrogen productivity among the catalysts tested is achieved with a 3%Pt-3%Re/C catalyst with added KOH base, but this hydrogen productivity declines with time on stream. The observed product distributionsmore » as well as deactivation with base can be understood in terms of the different reaction pathways that become emphasized depending on catalyst composition and pH.« less

Rh and Co-based catalyst performance was compared for steam reforming of ethanol under conditions suitable for industrial hydrogen production. The reaction conditions were varied to elucidate the differences in reaction pathways on both catalysts. On Co/ZnO, CH(4) is a secondary product formed through the methanation reaction, while it is produced directly by ethanol decomposition on Rh. The difference in the reaction pathway is shown to favor Co-based catalysts for selective hydrogen production under elevated system pressures (up to 15 bar) of industrial importance. The carbon deposition rate was also studied, and we show that Co is more prone to coking and catalyst failure. However, the Co/ZnO catalyst can be regenerated, by mild oxidation, despite the high carbon deposition rate. We conclude that Co/ZnO is a more suitable catalyst system for steam reforming of ethanol due to the low methane selectivity, low cost and the possibility of regeneration with mild oxidation. (C) 2010 Elsevier B.V. All rights reserved.

With efficient energy recovery, calcium-oxide-based absorbents that operate at elevated temperatures have an advantage over absorbents that operate at lower temperatures for CO2 capture from coal power plants. The major limitation of these absorbents is that the carbonation and decarbonation reactions of CaO and CaCO3 are far from complete or reversible. Rapid loss of CO2 capacity over many carbonation/decarbonation cycles is always observed because of severe absorbent sintering. We have found that this sintering effect can be effectively mitigated by properly mixing calcium oxide precursors with small rod-like MgAl2O4 spinel nanoparticles. A new class of CaO-based absorbents with much improved high-temperature durability was developed by wet physical mixing of calcium acetate with nano MgAl2O4 spinel particles followed by high-temperature calcination. CaO−MgAl2O4 (32 wt % spinel content) material provides 34 wt % CO2 capacity after 65 carbonation−decarbonation cycles (650 and 850 °C, respectively), corre...

The A5V star Alcor has an M3-M4 dwarf companion, as evidenced by a novel astrometric technique. Imaging spectroscopy combined with adaptive optics coronagraphy allowed for the detection and spectrophotometric characterization of the point source at a contrast of ~6 J- and H-band magnitudes and separation of 1" from the primary star. The use of an astrometric pupil plane grid allowed us to determine the projected separations between the companion and the coronagraphically occulted primary star to, submitted to ApJ on Nov 11, 2009; accepted for publication in ApJ on Dec 7, 2009; 10 pages, 3 figures

Metal and metal oxide nanoparticles supported on high surface area materials are widely used in industry for fuel and chemical production and for environmental pollution control, but preventing nanosized particle sintering has remained a great challenge. In this paper, we report that Ni−Cu alloy nanoparticles can be effectively stabilized in cubic mesostructured silica (SBA-16) following a conventional impregnation and thermal treatment process. The three-dimensional interconnected cage structure of the mesoporous SBA-16 allows good accessibility of reactant gas molecules to the metal nanoparticles and confines these particles within its nanosized cages. This confinement hinders metal nanoparticle migration and sintering under harsh conditions. A new class of regenerable metal-based adsorbents which can remove sulfur impurities from warm syngas stream down to less than 60 parts per billion by volume (ppbv) is described. This same confinement strategy is expected to have impact for minimizing sintering or ...

Calcium oxide based materials are attractive regenerable absorbents for separating CO{sub 2} from hot gas streams because of their high reactivity, high CO{sub 2} capacity, and low material cost. Their high carbonation temperature makes it possible to recover and use high quality heat released during CO{sub 2} capture, which increases overall process efficiency. However, the performance of all reported CaO-based absorbents deteriorates as the number of carbonation-decarbonation cycles increases. This is caused by absorbent sintering during the highly exothermic carbonation process. We have found that sintering can be effectively mitigated by properly mixing with a modest amount of MgO. A class of CaO-based absorbents with improved durability and CO{sub 2} reactivity were prepared by physical mixing of Ca(CH{sub 3}COO){sub 2} with small MgO particles followed by high temperature calcination. With 26 wt % MgO content, a CaO-MgO mixture prepared by this method gives as high as 53 wt % CO{sub 2} capacity after 50 carbonation-decarbonation cycles at 758{sup o}C. Without MgO addition, the CO{sub 2} capacity of pure CaO obtained from the same source decreases from 66 wt % for the first cycle to 26 wt % for the 50th cycle under the same test conditions.

Concentrating CO2 from the dilute coal combustion or gasification gas stream to a level suitable for sequestration purposes represents a major cost factor to curtail CO2 emissions by capture and sequestration. This paper provides a short review of CO2 capture incentives, current separation processes, and research progress of various new technologies. Scientifically, CO2 can be separated from a gas mixture by all the methods reviewed in this work: distillation, absorption, adsorption, gas/solid reaction, membrane, electrochemical pump, hydrate formation, etc. The challenge lies in practical feasibility and ultimately the cost. Important material issues and their impacts to the process viability will be discussed.

Currently, hydrogen is primarily used in the chemical industry, but in the near future it will become a significant fuel. There are many processes for hydrogen production. This paper reviews the technologies related to hydrogen production from both fossil and renewable biomass resources including reforming (steam, partial oxidation, autothermal, plasma, and aqueous phase) and pyrolysis. In addition, electrolysis and other methods for generating hydrogen from water, hydrogen storage related approaches, and hydrogen purification methods such as desulfurization and water-gas-shift are discussed.

The activity of nickel–yttria stabilized zirconia (Ni–YSZ) solid oxide fuel cell (SOFC) cermet anodes for the steam-reforming of methane has been investigated in the absence of electrochemical effects. The cermet was prepared by co-milling and sintering NiO and 5YSZ powders at 1375 °C in air. During the high-temperature sintering step, NiO dissolved into the YSZ particles to form a solid NiO–YSZ solution. During the subsequent catalyst reduction step, Ni exolved from the YSZ. As a result, many small Ni particles on the order of 10–20 nm formed at the surface of the YSZ. These small particles contributed significantly to the overall reforming activity, along with the large bulk Ni particles within the Ni–YSZ cermet. We observed high initial activity that decreased by as much as an order of magnitude with time on stream, until the anode catalyst reached a stable steady-state activity. The time to reach this stable activity was a function of the pretreatment and reaction conditions. Initial and lined-out activities and average turnover frequencies were obtained for both Ni–YSZ and bulk Ni, based on a rate expression that was first-order in methane and zero-order in steam. Comparative tests at 750 °C showed high initial activity on a per-Ni site basis with both materials, but these turnover rates declined over a period of a few hours. After lineout, there appeared to be a negligible effect of Ni particle size on turnover rate. These results indicate the presence of structure-sensitivity for methane reforming, but only with freshly calcined and reduced catalysts that may contain highly coordinatively unsaturated sites. There was an apparent structure-insensitivity with aged catalysts in which Ni particle sizes were generally ⩾30 nm. Under reaction conditions with high space velocities and low methane conversions, the water–gas shift reaction did not establish thermodynamic equilibrium.

A field-deployable process for generation of clean desulfurized fuel from JP-8 feedstock is described. The process employs a compact hydrodesulfurization unit, operated in the vapor phase using steam reformate provided by an integrated steam reformer, as a replacement for hydrogen co-feed gas. The process includes a microchannel distillation unit upstream of the hydrodesulfurizer unit, which allows use of a lighter feed fraction to be processed in place of the full JP-8. The novel microchannel distillation concept is described and performance data for the unit, operating as a rectifier, are provided. Since the generated light fraction fuel from microchannel distillation contains fewer refractory sulfur components, the subsequent HDS process can readily achieve a significant sulfur reduction. The overall process can generate an ultra-clean JP-8 light fraction fuel with approximately 300 ppb sulfur residual. Hydrodesulfurization of full JP-8 fuel without the microchannel distillation unit was also studied. The effect of various operating parameters on the overall hydrodesulfurization performance, as well as the conversion of some individual sulfur components such as 2,3-dimethyl-benzothiophene, 2,3,5-trimethyl-benzothiophene and 2,3,7-trimethyl-benzothiophene, were investigated. Steam content in reformate at 30 mol% or less was found to improve HDS performance compared with dry reformate, despite a decrease in hydrogen partial pressure. However, at even higher concentrations of steam, hydrodesulfurization performance decreased.

A series of Rh catalysts on various supports (Al2O3, MgAl2O4, ZrO2, and ZrO2–CeO2) have been applied to H2 production from the ethanol steam reforming reaction. In terms of ethanol conversion at low temperatures (below 450 °C) with 1wt% Rh catalysts, the activity decreases in the order: Rh/ZrO2–CeO2 > Rh/Al2O3 > Rh/MgAl2O4 > Rh/ZrO2. Support plays a very important role on product selectivity at low temperatures (below 450 °C). Acidic or basic supports favor ethanol dehydration, while ethanol dehydrogenation is favored over neutral supports at low temperatures. The Rh/ZrO2–CeO2 catalyst exhibits the highest CO2 selectivity up to 550 °C, which is due to the highest water gas shift (WGS) activity at low temperatures. Among the catalysts evaluated in this study, the 2wt% Rh/ZrO2–CeO2 catalyst exhibited the highest H2 yield at 450 °C, which is possibly due to the high oxygen storage capacity of ZrO2–CeO2 resulting in efficient transfer of mobile oxygen species from the H2O molecule to the reaction intermediate.

Rapid deactivation of Rh/Ce0.8Zr0.2O2 catalysts during low temperature ethanol steam reforming was studied. A significant build-up of reaction intermediates, instead of carbon deposit, was observed at low reaction temperatures. This appears to be the cause of rapid catalyst deactivation. Co-feed experiments indicated that possible intermediate products acetone and ethylene caused more severe catalyst deactivation than other oxygenates such as acetic acid and acetaldehyde.

Metal-organic frameworks (MOFs) have proved to be very attractive for applications including gas storage, separation, sensing and catalysis. In particular, CO(2) separation from flue gas in post-combustion processes is one of the main focuses of research among the scientific community. One of the major issues that are preventing the successful commercialization of these novel materials is their high affinity towards water that not only compromises gas sorption capacity but also the chemical stability. In this paper, we demonstrate a novel post-synthesis modification approach to modify MOFs towards increasing hydrophobic behaviour and chemical stability against moisture without compromising CO(2) sorption capacity. Our approach consists of incorporating hydrophobic moieties on the external surface of the MOFs via physical adsorption. The rationale behind this concept is to increase the surface hydrophobicity in the porous materials without the need of introducing bulky functionalities inside the pore which compromises the sorption capacity toward other gases. We herein report preliminary results on routinely studied MOF materials [MIL-101(Cr) and NiDOBDC] demonstrating that the polymer-modified MOFs retain CO(2) sorption capacity while reducing the water adsorption up to three times, with respect to the un-modified materials, via an equilibrium effect. Furthermore, the water stability of the polymer-functionalized MOFs is significantly higher than the water stability of the bare material. Molecular dynamic simulations demonstrated that this equilibrium effect implies a fundamental and permanent change in the water sorption capacity of MOFs. This approach can also be employed to render moisture stability and selectivity to MOFs that find applications in gas separations, catalysis and sensing where water plays a critical role in compromising MOF performance and recyclability.

This paper describes the preliminary design of the software that will perform real-time control of the adaptive optics section of a new astronomical instrument that will combine the benefits of low order adaptive optics with lucky imaging. Such combination will allow astronomers to obtain near diffraction limited images in the visible spectrum on large ground-based telescopes using faint natural guide stars.

The addition of small quantities of gold to the surface of supported nickel catalysts has been described as a means to retard carbon formation during hydrocarbon steam reforming. Calculations by others have indicated that gold locates at the most catalytically active (step and edge) sites that also serve as nucleation sites for carbon formation. In this paper, we describe experiments to characterize the Ni Au interactions on bimetallic Au Ni/MgAl 2 O 4 catalysts at various Ni and Au loadings. The catalyst structure was investigated using EXAFS/XANES spectroscopy and adsorption–desorption measurements with H 2 and N 2 O. Evidence for surface alloy formation is provided in the Ni K-edge and Au L III -edge EXAFS measurements of Au-promoted 8.8% Ni/MgAl 2 O 4 , especially at Au loadings ⩽ 0.2 wt% . At higher Au concentrations, there is evidence of a combination of alloy and segregated Au species. H 2 chemisorption and N 2 O temperature-programmed desorption (TPD) measurements showed a significant decrease in total surface sites, or surface site reactivity, on Au-modified Ni/MgAl 2 O 4 catalyst. The XANES structure is consistent with perturbation of the electronic structure of both the Ni and Au atoms as a result of alloy formation. TGA studies with steam/ n -butane feed confirmed the ability of Au to retard coke deposition under low S/C reforming conditions, although carbon formation was not fully suppressed. When testing for methane steam reforming, a lower initial activity and deactivation rate resulted from Au promotion of the Ni catalyst. However, both catalysts showed a declining activity with time. The lack of a direct correlation between the surface characterization results and catalytic activity is most likely a result of decreasing effectiveness of the surface alloy with increasing temperature.

Gas-phase hydrodesulfurization of a JP-8 light fraction was investigated over CoMo/Al2O3 and NiMo/Al2O3 catalysts. Use of a light fraction provides a fuel that is more easily desulfurized and allows the process to operate in the vapor phase. This study investigated the utilization of reformate (syngas) from a steam reformer rather than pure H2 as gas feed to HDS unit. This is consistent with what might be available to the military during operation in the field. Dry syngas functions almost as well as pure H2 in the HDS reaction, and sulfur levels below 5 ppmw are readily obtained from a feed initially containing 320 ppmw sulfur. Addition of 40 vol % steam to the syngas has a significant negative impact on HDS performance with CoMo/Al2O3, but only a small effect with NiMo/Al2O3. The impacts of various process conditions on S removal efficiency were examined and will be described.

The desulfurization of Tier 2 gasoline ( + (CuNaY) or H + (CuHY). Capacities on the order of 60 ml gasoline/g adsorbent were obtained with both materials before the sulfur concentration in the effluent exceeded 3 ppmw. Overall, the CuHY zeolite showed somewhat better desulfurization performance. It is proposed that acid sites (H + ) that are present play a role in the desulfurization process, facilitating chemical reactions involving the sulfur-containing molecules. This leads to the generation of sulfur-bearing compounds having molecular weights and sizes greater than those present in the initial feed. Some of these heavier sulfur species are eluted but many do not elute. The net effect is a desulfurization pathway that is the result of entrapment of sulfur-containing molecules in addition to a desulfurization pathway involving direct interaction between the copper and sulfur atoms.

The efficacy of using ZnO as an absorber for the removal of H2S from small fuel processor steam reformate streams was examined. At temperatures below 300 °C, H2S can in principle be reduced to below 100 ppbv, required for safe operation of PEM fuel cells. The ZnO adsorbent performed predictably based on ZnO-H2S-ZnS-H2O equilibria with steam, hydrogen, and CO2 in the feed. However, addition of CO even at levels as low as 1 vol% drastically lowered the sulfur removal capability of the ZnO. This is consistent with the formation of COS by the reaction H2S + CO = H2 + COS. ZnO is not an efficient absorber for COS. Indirect evidence is also provided for the formation of COS via the reaction CO2 + H2S = COS + H2O, which can occur in special cases when CO2 is present but neither H2O nor CO is present in the feed. The potential for COS formation compromises the ability of ZnO to deliver very low sulfur concentration reformate.