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Results for “SUPPORTS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Surface Organometallic Chemistry of Supported Iridium(III) as a Probe for Organotransition Metal–Support Interactions in C–H Activation
Systematic study of the interactions between organometallic catalysts and metal oxide support materials is essential for the realization of rational design in heterogeneous catalysis. Herein we describe the stoichiometric and catalytic chemistry of a [Cp*(PMe 3 )Ir(III)] complex chemisorbed on a variety of acidic metal oxides as a multifaceted probe for stereoelectronic communication between the support and organometallic center. Electrophilic bond activation was explored in the context of stoichiometric hydrogenolysis as well as catalytic H/D exchange. Further information was obtained from the observation of processes related to dynamic exchange between grafted organometallic species and those in solution. The supported organometallic species were characterized by a variety of spectroscopic techniques including dynamic nuclear polarization-enhanced solid-state NMR spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption spectroscopy. Finally, strongly acidic modified metal oxides such as sulfated zirconia engender high levels of activity toward electrophilic bond activation of both sp 2 and sp 3 C–H bonds, including the rapid deuteration of methane at room temperature; however, the global trend for the supports studied here does not suggest a direct correlation between activity and surface Brønsted acidity.
Reversing Size-Dependent Trends in the Oxidation of Copper Clusters through Support Effects: Reversing Size-Dependent Trends in the Oxidation of Copper Clusters through Support Effects
Having the ability to tune the oxidation state of Cu nanoparticles is essential for their utility as catalysts. The degree of oxidation that maximizes product yield and selectivity is known to vary, depending on the particular reaction. Using first principles calculations and XANES measurements, we show that for subnanometer sizes in the gas phase, smaller Cu clusters are more resistant to oxidation. However, this trend is reversed upon deposition on an alumina support. We are able to explain this result in terms of strong cluster-support interactions, which differ significantly for the oxidized and elemental clusters. The stable cluster phases also feature novel oxygen stoichiometries. Our results suggest that one can tune the degree of oxidation of Cu catalysts by optimizing not just their size, but also the support they are deposited on.
Review of TEAMER Awards for WEC-Sim Support: Preprint
Testing Expertise and Access for Marine Energy Research (TEAMER) is a U.S. Department of Energy Water Power Technologies Office sponsored program, overseen by the Pacific Ocean Energy Trust, which aims to advance the state of marine energy technologies. The program connects technology developers with experts at U.S. facilities, including numerical modeling and analysis facilities, like WEC-Sim. The WEC-Sim facility is supported by the WEC-Sim development team at Sandia National Laboratories and the National Renewable Energy Laboratory. WEC-Sim (Wave Energy Converter SIMulator) is an open-source software for simulating wave energy converters. WEC-Sim can model the multi-body dynamics of devices comprised of bodies, joints, power take-off systems, and mooring systems. Since TEAMER's first round of support in 2020, there have been eighteen TEAMER awards focused on numerical model development in WEC-Sim. TEAMER awards for WEC-Sim support have modeled a wide range of wave energy converter archetypes, including point absorbers, attenuators, oscillating water columns, and many other novel architectures. A wide variety of studies have been conducted, leading to important insights for TEAMER partners and software improvements for WECSim. This article highlights several successful WEC-Sim TEAMER awards. The awards described herein include TEAMER recipients Ocean Motion Technologies, AquaHarmonics, iProTech, East Carolina University, Virginia Tech, Maiden Wave Energy, and the University of Massachusetts Dartmouth. The awards of these seven partners contain a wide range of investigations and cover the creation of baseline hydrodynamic models, PTO modeling, geometry optimization in both boundary element methods and WECSim, and model tuning and validation.
Water-gas shift: Characterization and testing of nanoscale YSZ supported Pt catalysts
Nano-scale Y-doped zirconium oxide materials were prepared with high surface areas (150-200 m(2)/g) and small nano-crystallites (<8 nm). A combination of XANES and EXAFS was used to show that ZrO2 exhibited the tetragonal phase, while the Zr0.5Y0.5O1.75 support displayed the cubic phase. A comparison with undoped zirconia suggests that the Zr0.9Y0.1O1.95 support was tetragonal in structure. A slight increase in d-spacing observed in HR-TEM for the Zr0.9Y0.1O1.95 support relative to undoped ZrO2, along with a shift to lower 2 theta in XRD, provide evidence that Y-doping caused macrostrain. STEM imaging confirmed that the Pt clusters ranged from 0.5 to 2 nm over all three supports. Catalyst reducibility was explored by H-2-TPR, XANES at the Zr K-edge, and TPR-XANES at the Pt L-III edge. A higher concentration of surface defects for the 0.5%Pt/Zr0.9Y0.1O1.95 catalyst relative to 0.5%Pt/ZrO2 was confirmed by DRIFTS of adsorbed CO, while a greater surface mobility of surface formate was suggested based on forward formate decomposition experiments in steam. The Y-doped Pt promoted catalysts displayed higher water-gas-shift activity relative to the 0.5%Pt/ZrO2 catalyst when the Y content was at or below 50%, with the best catalyst being 0.5%Pt/Zr0.9Y0.1O1.95. (C) 2015 Elsevier B.V. All rights reserved.
Evaluating the Activity of Heterogeneous Tertiary Amine Catalysts for Glucose Isomerization to Fructose by Tuning Catalyst, Support, and Reaction Conditions
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Protonation Studies of a Mono-Dinitrogen Complex of Chromium Supported by a 12-Membered Phosphorus Macrocycle Containing Pendant Amines
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Workshop on Establishing and Operating a National Nuclear Security Support Centre Hypothetical Scenario: “Centralia Nuclear Security Support Centre Technical Support Plan”
This plan outlines the systemic and coordinated management of the CNSSC technical support programme. In accordance with the CNSSC Strategy Implementation Plan and Memoranda of Understanding among stakeholders, Centralia Border Guards (CBG) and Centralia Nuclear Energy Agency (CNEA) will lead the effort to develop standardized approach to technical support and will provide technical support to the following CNSSC stakeholders: CBG, CNEA, Centralia National Police (CNP), Centralia Coast Guard (CCG), and CentrAtom/Centralia Nuclear Power Plant (CNPP).
Synthesis and Protonation Studies of Molybdenum(0) Bis(dinitrogen) Complexes Supported by Diphosphine Ligands Containing Pendant Amines
A series of molybdenum bis(dinitrogen) complexes of the formula trans-Mo(N2)2(PEtNRPEt)2 (PEtNRPEt = Et2PCH2N(R)CH2Et2; R = phenyl (1), 2,6-difluorobenzyl (2), 3,5-difluorobenzyl (3), CH2CH2NMe2 (4), CH2-o-Py (5)) have been synthesized and characterized by NMR and IR spectroscopy, and X-ray crystallography. Protonation studies with stoichiometric amounts of triflic acid (HOTf) were performed and the the protonated products were characterized by NMR and in situ IR spectroscopic methods. Protonolysis experiments with excess triflic acid were conducted to test for the formation of ammonia from reduction of the dinitrogen ligands. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences. S.L. was supported by the DOE Office of Science, Early Career Research Program through the Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE.
Dinitrogen Reduction by a Chromium(0) Complex Supported by a 16-Membered Phosphorus Macrocycle
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Unexpected “Spontaneous” Evolution of Catalytic, MOF-Supported Single Cu(II) Cations to Catalytic, MOF-Supported Cu(0) Nanoparticles
A desirable feature of metal–organic frameworks (MOFs) is their well-defined structural periodicity and the presence of well-defined catalyst grafting sites (e.g., reactive –OH and –OH 2 groups) that can support single-site heterogeneous catalysts. However, one should not overlook the potential role of residual organic moieties, specifically formate ions that can occupy the catalyst anchoring sites during MOF synthesis. Here we show how these residual formate species in a Zr-based MOF, NU-1000, critically alter the structure, redox capability, and catalytic activity of postsynthetically incorporated Cu(II) ions. Single-crystal X-ray diffraction measurements established that there are two structurally distinct types of Cu(II) ions in NU-1000: one type with residual formate and one without. In NU-1000 with formate, Cu(II) solely binds to the node via the formate-unoccupied, bridging μ 3 –OH, whereas in the formate-free case, it displaces protons from two node hydroxo ligands and resides close to the terminal –OH 2 . Under an inert atmosphere, node-bound formate facilitates the unanticipated reduction of isolated Cu(II) to nanoparticulate Cu(0)—a behavior which is essentially absent in the formate-free analogue because no other sacrificial reductant is present. When the two MOFs were tested as benzyl alcohol oxidation catalysts, we observed that residual formate boosts the catalytic turnover frequency. Density functional calculations showed that node-bound formate acts as a sacrificial two-electron donor and assists in reducing Cu(II) to Cu(0) by a nonradical pathway. The negative Gibbs free energy of reaction (ΔG) and enthalpy of reaction (ΔH) indicate that the reduction is thermodynamically favorable. Here, the work presented here highlights how the often-neglected residual formate prevalent in nearly all zirconium-based MOFs can significantly modulate the properties of supported catalysts.
Theoretical Study of Reductive Functionalization of Methyl Ligands of Group 9 Complexes Supported by Two Bipyridyl Ligands: A Key Step in Catalytic Hydrocarbon Functionalization
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In situ Environmental Transmission Electron Microscopy Study of Oxidation of Two-Dimensional Ti3C2 and Formation of Carbon-Supported TiO2
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Interconnection Standard Grid-Support Function Evaluations Using an Automated Hardware-in-the-Loop Testbed
Grid operators are increasingly turning to advanced grid-support functions in distributed energy resources (DER) to assist with distribution circuit voltage regulation, bulk system frequency control, and power system protection. The U.S. DER certification standard, Underwriters Laboratories (UL) 1741, was revised in September 2016 to add test procedures for multiple grid-support functions. Sandia National Laboratories, SunSpec Alliance, and growing community of collaborators have undertaken a multiyear effort to create an open-source system validation platform (SVP) that automates DER interconnection and interoperability test procedures by communicating with grid simulators, photovoltaic (PV) simulators, data acquisition systems, and interoperable equipment under test. However, the power hardware required for generating the test conditions may be untenable for many organizations. In this paper, we discuss development of the SVP testing capabilities for UL 1741 tests utilizing a controller hardware-in-the-loop testbed that precludes the need for power hardware using a 34.5 kW Austrian Institute of Technology smart grid controller. Finally, analysis of normal ramp rate, soft start ramp rate, specified power factor, volt-VAr, and frequency-watt advanced grid functions, and the effectiveness of the UL 1741 test protocols are included.
Control of Metal Nanocrystal Size Reveals Metal-Support Interface Role for Ceria Catalysts
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