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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Screening of Cu-Based Catalysts for Selective Methane to Methanol Conversion

Developing selective catalysts for methane conversion to added value chemicals has been considered as a promising approach for efficient utilization of abundant natural gas resources. Here, we present a descriptor-based screening for high methane conversion and methanol selectivity at the interfaces between metal oxide clusters and Cu 2 O/Cu(111) support (MO x /Cu 2 O/Cu(111), M = Mg, Fe, Co, Ni, Cu, Zn, Ti, Zr, Sn, Ce) on exposure to the mixture of CH 4 /O 2 /H 2 O. Wherein, the activation energy of direct methane to methanol conversion, *OH + *CH 4 → *CH 3 OH + *H, and the ratio for adsorption energy of oxygen and water, E ads (O 2 )/E ads (H 2 O), are identified as the effective descriptor for methane conversion and methanol selectivity, respectively. Finally, by providing an exceptional oxygen and hydroxyl sites with high-lying O 2p states, the MgO/Cu 2 O/Cu(111) catalyst is found to be the most promising system among the systems studied, being able to provide the highest methane conversion with high methanol selectivity.

03 NATURAL GAS↗
DOE OSTI2025

Oxygen Reduction on Platinum-Nickel and Platinum-Cobalt Alloy Based Catalysts for High Temperature Proton Exchange Membrane Fuel Cells

Catalyst layers, with commercial PtNi/TKK (TECNiE52; platinum 46.5 wt%), PtCo/TKK (TEC36E52; platinum 45.8 wt%) catalysts, and an in-house catalyst PtNi-NC (platinum 38.4 wt%), synthesised using acoustic mixer and a tube furnace, are prepared using three different ionomers: 20 wt% Nafion®, 60 wt% polytetrafluoroethylene (PTFE), and an in-house 5 wt% ionomer (‘Ionomer X’). These inks are bar-coated onto carbon paper gas diffusion layers (GDLs), which are cut into 3 cm × 5 cm pieces. The coated layers are tested for oxygen reduction in a commercial gas diffusion electrode (GDE) test cell, FlexCell® (Gaskatel GmbH, Germany), using 85 wt% phosphoric acid at both room temperature and at 155°C. This study evaluates the polynorbornene (PNB)-based in-house ionomer performance as binder and in-house catalyst oxygen reduction reaction (ORR) activity in comparison to commercial products. The catalyst layers are characterised using X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Among the catalyst layers prepared with PTFE ionomer and tested at 155°C, the in-house catalyst demonstrates the highest ORR activity. Ionomer X proves to be a good candidate to be used as a per- and polyfluoroalkyl-free binder for high-temperature (HT) proton exchange membrane fuel cell (PEMFC) applications.

85 wt% phosphoric acid↗
DOE OSTI2025

Enhancing electrocatalytic performance of RuO 2 -based catalysts: mechanistic insights, strategic approaches, and recent advances

Abstract Electrochemical water splitting presents the ultimate potential of hydrogen and oxygen production; however, regulating the rate and efficiency of water splitting is highly dependent on the accessibility of extremely efficient electrode materials for slow performance kinetics and large overpotential of both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Ruthenium oxide (RuO 2 ) based materials display high performance for OER and HER because of their capacity to bind oxygen, eminent catalytic activity, low cost compared to other precious metals, and stability in a wide pH range. However, there is still much space to promote the OER and HER activity and stability of RuO 2 to fulfill the necessity for practical applications in water splitting. Different researchers applied multiple approaches that boosted the catalytic performance of RuO 2 -based electrocatalysts toward overall water splitting. Herein, this review provides a comprehensive overview of recent advancements in RuO 2 -based materials in the field of water electrolysis for the generation of alternative energies. It gives a general description of water splitting in acidic and alkaline settings, including reaction mechanisms as well as common evaluation elements for the catalytic function of the materials. Most of the reviews reported based on RuO 2 materials are only focused on OER performance, but this review highlighted comprehensive ideas on different strategies like morphology design, electronic structure, electrolytes, and compositions for optimizing both electrocatalytic HER and OER functioning of RuO 2 -based electrocatalysts.

KC, Binod Raj (ORCID:0009000885806906)↗
DOE OSTI2024

Zeolite‐Based Catalysts for Conversion of Oxygenated Polymer Waste by Positron Annihilation

Positron Annihilation Lifetime Spectroscopy (PALS) has been employed to investigate the catalysts HZSM-5 and MESO−Y, which play a pivotal role in catalyzing and upgrading plastics, with a primary focus on oxygenated polymers, thereby transforming existing plastic materials into simpler, higher-quality value-added products. Here, in this study, PALS was systematically compared with other complementary analytical techniques. The research outcomes have successfully demonstrated the efficacy of PALS in elucidating the morphology and topology of zeolites at micro/meso-meter scales. The first experiment focuses on H-ZSM-5 zeolite subjected to treatments involving polyurethane and polypropylene. The second experiment delves into H-ZSM-5 zeolites with varying Si/Al ratios, both before and after conversion. The third experiment investigates Y zeolites that are surfactant templated to induce meso-porosity, examining their fresh state as well as their post-conversion condition. The PALS analysis was supplemented by BET (Brunauer-Emmett-Teller) analysis and NMR (Nuclear Magnetic Resonance) spectroscopies. Notably, PALS exhibits superior sensitivity, at the sub-nanometer scale, suggesting its potential as a preferred complementary method for catalysis studies. In conclusion, the integration of PALS into the repertoire of analytical tools enhances our understanding of catalyst behavior and catalytic processes, offering valuable insights for the advancement of plastic recycling and catalysis research.

32 - ENERGY CONSERVATION, CONSUMPTION, AND UTILIZA↗
DOE OSTI2021

Systematic Influence of Electronic Modification of Ligands on the Catalytic Rate of Water Oxidation by a Single-Site Ru-Based Catalyst

Catalytic water oxidation is an important process for the development of clean energy solutions and energy storage. Despite the significant number of reports on active catalysts, systematic control of the catalytic activity remains elusive. In this study, descriptors are explored that can be correlated with catalytic activity. [Ru(tpy)(pic) 2 (H 2 O)](NO 3 ) 2 and [Ru(EtO-tpy)(pic) 2 (H 2 O)](NO 3 ) 2 (where tpy=2,2': 6',2“-terpyridine, EtO-tpy=4'-(ethoxy)-2,':6',2”-terpyridine, pic=4-picoline) are synthesized and characterized by NMR, UV/Vis, EPR, resonance Raman, and X-ray absorption spectroscopy, and electrochemical analysis. Addition of the ethoxy group increases the catalytic activity in chemically driven and photocatalytic water oxidation. Thus, the effect of the electron-donating group known for the [Ru(tpy)(bpy)(H 2 O)] 2+ family is transferable to architectures with a tpy ligand trans to the Ru-oxo unit. Under catalytic conditions, [Ru(EtO-tpy)(pic) 2 (H 2 O)](NO 3 ) 2 displays new spectroscopic signals tentatively assigned to a peroxo intermediate. In conclusion, reaction pathways were analyzed by using DFT calculations. [Ru(EtO-tpy)(pic) 2 (H 2 O)](NO 3 ) 2 is found to be one of the most active catalysts functioning by a water nucleophilic attack mechanism.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts

In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/g cat methanol, or ~23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ~80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO) 2 species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.

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

Heterogeneous hydroformylation of alkenes by Rh-based catalysts

Heterogeneously catalyzed hydroformylation reactions avert the problems of separation in homogeneous reactions, reduce the discharge of phosphorus-containing wastes, and prevent the loss of precious metals. This review summarizes the developments of catalysts for heterogeneous hydroformylation in the last decade and proposes potential modification methods for future improvements. The hydroformylation properties of different reactants are compared in order to emphasize the fact that various olefins face unique challenges. The hydroformylation of ethylene requires the enhancement of catalytic activity and chemoselectivity, whereas that of propylene needs improvements in both chemoselectivity and regioselectivity. The hydroformylation of longer-chain olefins and styrene seeks further improvement in regioselectivity. The catalytic properties of activity, selectivity, and stability can be tuned through electronic effects (bimetallic effects, phosphine ligands, and single-atom catalysts), steric hindrance (encapsulation structures, diphosphine ligands, and local functional groups), and reaction condition optimization (temperature, pressure, and solvents). Furthermore, the understanding of these effects is critical in future catalyst design for heterogeneous hydroformylation reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Retrofitting of carbon-supported bimetallic Ni-based catalysts by phosphorization for hydrogen evolution reaction in acidic media

Commercial bimetallic Ni–Mo and Ni–Re electrocatalysts supported on advanced conductive carbon are high-performing materials for H 2 evolution reaction in alkaline medium, but they cannot be applied in acidic medium due to the rapid dissolution of metals. Here, in this work, we solve this issue by introducing a convenient phosphorization protocol to convert these commercial metallic electrocatalysts into the respective phosphides, rendering them stable under acidic conditions, and thus providing a pathway to electrocatalysts for water reduction in acidic electrolyte. The novel materials demonstrate high performance, as reflected by the measured low overpotentials, shallow Tafel slopes, fast kinetics, as well as excellent stability and durability. This work opens the possibility to expand the applicability of commercial supported metallic catalysts and electrocatalysts through retrofitting via phosphorization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗