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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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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Single-Step Conversion of Ethanol to n-Butene over Ag-ZrO2/SiO2 Catalysts

Ethanol is a promising platform molecule for production of a variety of fuels and chemicals. Of particular interest is producing middle distillate fuels (i.e., jet and diesel blendstock) from renewable ethanol feedstock. State-of-the-art alcohol-to-jet technology requires multiple process steps based on catalytic dehydration of ethanol to form ethylene, followed by sometimes a multi-step oligomerization, and then hydrotreatment and distillation. Here we report on a new catalytic route in which ethanol is directly converted to n-butene (1- and 2-butene mixtures) over Ag-ZrO2/SBA-16, thus offering the potential for a reduction in the number of required processing steps versus conventional alcohol-to-jet technology. This catalyst system provides the balanced metal and Lewis acid sites required to selectively facilitate a cascading sequence of reactions that includes dehydrogenation, aldol condensation, Meerwein–Ponndorf–Verley reduction, dehydration, and hydrogenation. High conversion and selectivity toward either n-butene or 1,3-butadiene is achieved by tuning the hydrogen feed partial pressure and other process/catalyst parameters. With sufficient hydrogen partial pressure 1,3-butadiene is completely and selectively hydrogenated to form n-butene. The reaction mechanism was elucidated through operando-nuclear magnetic resonance investigations coupled with reactivity measurements. Combined experimental-computational investigation reveals how changes in silver and zirconium composition and the silver oxidation state affects reactivity under controlled hydrogen partial pressures and after prolonged run times. Finally, catalyst effectiveness also was demonstrated when using wet ethanol feed, thus highlighting process flexibility in terms of feedstock purity requirements. This work was financially supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office, and was performed at the Pacific Northwest National Laboratory (PNNL) under Contract No. DE-AC05-76RL01830 and the National Renewable Energy Laboratory under Contract No. DE-AC36- 08GO28308. Part of the work conducted by S. A. Akhade was performed under the auspices of the U.S. DOE at Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. This work was partly supported through the PNNL-WSU Distinguished Graduate Research Program for ADW. NMR and XPS experiments were performed using EMSL (grid.436923.9), a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research

Dagle, Vanessa↗
DOE OSTI2020

Carbide-Modified Pd on ZrO2 as Active Phase for CO2-Reforming of Methane—A Model Phase Boundary Approach

Starting from subsurface Zr0-doped “inverse” Pd and bulk-intermetallic Pd0Zr0 model catalyst precursors, we investigated the dry reforming reaction of methane (DRM) using synchrotron-based near ambient pressure in-situ X-ray photoelectron spectroscopy (NAP-XPS), in-situ X-ray diffraction and catalytic testing in an ultrahigh-vacuum-compatible recirculating batch reactor cell. Both intermetallic precursors develop a Pd0–ZrO2 phase boundary under realistic DRM conditions, whereby the oxidative segregation of ZrO2 from bulk intermetallic PdxZry leads to a highly active composite layer of carbide-modified Pd0 metal nanoparticles in contact with tetragonal ZrO2. This active state exhibits reaction rates exceeding those of a conventional supported Pd–ZrO2 reference catalyst and its high activity is unambiguously linked to the fast conversion of the highly reactive carbidic/dissolved C-species inside Pd0 toward CO at the Pd/ZrO2 phase boundary, which serves the role of providing efficient CO2 activation sites. In contrast, the near-surface intermetallic precursor decomposes toward ZrO2 islands at the surface of a quasi-infinite Pd0 metal bulk. Strongly delayed Pd carbide accumulation and thus carbon resegregation under reaction conditions leads to a much less active interfacial ZrO2–Pd0 state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Site and Structural Requirements for the Dehydra-Decyclization of Cyclic Ethers on ZrO2

In this study, we examined the site and structural requirements for the dehydra-decyclization of cyclic ethers, tetrahydrofuran, and tetrahydropyran to produce conjugated dienes over ZrO2-based catalysts, a reaction that could be an important step in the use of biomass-derived sugars as a starting material to produce monomers for the plastics industry. To help identify the active sites for this reaction, studies were conducted in which ZrO2 surfaces were decorated with Na. These studies showed that Na was effective at poisoning the activity for the ring opening of cyclic ethers, but much less so for the dehydration of the resulting adsorbed alkoxides. The studies of the activity of different types of ZrO2 for the dehydra-decyclization reaction, including single crystals and ultra-thin films supported on MgAl2O4 and silica, also showed that the reaction was dependent on the local structure of the ZrO2 surface. The insights these results provide for identifying the active sites on the ZrO2 surface are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Zr4+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Zr–O bond lengths are 2.23 Å. O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. Zr4+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. There are four shorter (2.09 Å) and four longer (2.44 Å) Zr–O bond lengths. O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Baddeleyite structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted corner and edge-sharing ZrO7 pentagonal bipyramids. There are a spread of Zr–O bond distances ranging from 2.07–2.31 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Zr4+ atoms. In the second O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of corner and edge-sharing OZr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing ZrO7 pentagonal bipyramids. There are a spread of Zr–O bond distances ranging from 2.06–2.30 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is beta Vanadium nitride-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are four shorter (2.10 Å) and two longer (2.18 Å) Zr–O bond lengths. O2- is bonded in a 3-coordinate geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing ZrO6 pentagonal pyramids. There are a spread of Zr–O bond distances ranging from 2.11–2.15 Å. O2- is bonded in a trigonal non-coplanar geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing ZrO7 hexagonal pyramids. There are a spread of Zr–O bond distances ranging from 2.08–2.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Zr–O bond distances ranging from 2.12–2.30 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Zr4+ atoms. In the second O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 32°. There are a spread of Zr–O bond distances ranging from 2.01–2.30 Å. In the second Zr4+ site, Zr4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Zr–O bond distances ranging from 1.95–2.46 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Zr4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Zr4+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Zr4+ atoms. In the fourth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Rutile structured and crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. All Zr–O bond lengths are 2.13 Å. O2- is bonded in a distorted trigonal planar geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 25°. There are a spread of Zr–O bond distances ranging from 2.07–2.19 Å. In the second Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are a spread of Zr–O bond distances ranging from 2.07–2.19 Å. In the third Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are two shorter (2.11 Å) and four longer (2.13 Å) Zr–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Zr4+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the sixth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrO2 by Materials Project

ZrO2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Zr–O bond distances ranging from 2.17–2.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to five equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Quantitative characterization of ZrO2 gate dielectric interface with tellurium

Tellurium (Te) has recently emerged as a promising p-type semiconductor that can be processed at low temperatures, compatible with back end of line CMOS integration. Characterization of tellurium–dielectric interfaces is essential for further device advancements. Here, the interface quality of Te with ZrO2 gate dielectric is studied in a metal-oxide semiconductor capacitor structure. The interface trap density (Dit) is measured as a function of atomic layer deposition (ALD) temperature, without the use of a seed layer. Given the low thermal budget of Te, the ALD temperature is shown to be particularly important. The lowest Dit of 5 × 1012 states/cm2 eV is obtained at a low ALD process temperature of 120 °C. To further assess the impact of Dit on device performance, field-effect transistors (FETs) were fabricated. The subthreshold swing and effective hole mobility of the FETs were analyzed in relation to Dit, emphasizing the importance of a defect-minimized interface for enhancing Te transistor performance.

Byeon, Kyeong-Jae↗
DOE OSTI2020

Atomic-Scale Imaging of Polarization Switching in an (Anti-)Ferroelectric Memory Material: Zirconia (ZrO2)

Direct, atomic-scale visualization of polarization switching in a functional, polycrystalline, binary oxide via in-situ high-resolution transmission electron microscopy (HRTEM) biasing is reported for the first time. Antiferroelectric (AFE) ZrO2 was used as the model system, which is important for commercial DRAMs and as emerging NVMs (through work-function engineering). We observed (1) clear shifting and coalescing of domains within a single grain, and (2) dramatic changes of the atomic arrangements and crystalline phases—both at voltages above the critical voltage measured for AFE switching. Similar synergistic in-situ structural-electrical characterization can pave the way to understand and engineer microscopic mechanisms for retention, fatigue, variability, sub-coercive switching and analog states in ferroelectric and AFE-based memory devices.

Lombardo, Sarah↗
DOE OSTI2020

Insights into the methanol synthesis mechanism via CO 2 hydrogenation over Cu-ZnO-ZrO2 catalysts: Effects of surfactant/Cu-Zn-Zr molar ratio

In this study, we evaluated aspects of the CO 2 hydrogenation mechanism, correlating structure-activity relationships of Cu-ZnO-ZrO 2 catalysts prepared by one-pot surfactant-assisted co-precipitation with different surfactant ratios. Identifying the CO 2 hydrogenation pathway intermediates is key to controlling the reaction selectivity. Experimental evidence shows that the CO 2 is dissociating into CO* and O* onto the surface of the Cu-ZnO-ZrO 2 catalyst. The adsorption and dissociation of CO2 were evidenced by a combination of in situ ambient-pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Fourier Transform Infrared Spectroscopy (FTIR) with a transmission cell. AP-XPS showed that the catalysts are composed of a Cu 2+ , Zr 3+ , and Zr 4+ mixture and two kinds of Zn 2+ species. After the H 2 reduction process, only Cu 2+ was reduced to Cu0. The Zn and Zr species were oxidized by the dissociated O* species. In situ transmission FTIR showed that CO was adsorbed onto the Cu+/0 sites. The catalyst with the higher surfactant molar ratio exhibited the highest CO 2 conversion close to the equilibrium conversion, as well as a good methanol formation rate.

36 MATERIALS SCIENCE↗