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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Effect of Catalyst Pretreatment on Methane Conversion under Microwave-assisted and Conventional Thermal Methods

The presentation was delivered from work performed in NETL's Upcycling of Associated Natural Gas FWP Task 4 Benzene, Toluene, Xylene Synthesis via Microwave-assisted catalyst. The objective of this project is to develop a modular, microwave-assisted reactor to upcycle flare gas into valuable chemicals. The presentation discusses important work researchers have performed to compare the pre-treatment of a benchmark Mo/ZSM-5 catalyst under microwaves to traditional thermal heating. Pre-treatment is required to enable to catalyst to produce benzene. This study provided insights into how the exposure impacts the structure and activity of the catalyst and will be used to help design better catalysts.

Abdelsayed, Victor↗
DOE OSTI2023

Nonprecious metal catalyst for hydrogen production from neutral solutions

Catalysts comprising MoP and MoP 2 are disclosed, wherein the catalyst is a composite. The catalyst may have a molar ratio of MoP:MoP 2 within a range of 5:95 to 95:5. The catalyst may be used as a cathode active material for hydrogen generation from neutral pH solutions, such as wastewater or seawater. Methods of making the catalyst also are disclosed.

Shao, Yuyan↗
DOE OSTI2023

Reaction process involving capillary condensation within a microporous catalyst

Described herein is a catalytic reaction process including introducing one or more gas-phase reactants into a reactor comprising a microporous catalyst having a pore size less than or equal to 2 nm and adjusting the temperature and/or the pressure of the reactor such that one or more of the gas-phase reactants condense within the micropores of the catalyst thereby causing the catalytic reaction to take place in a liquid phase. Additionally, a process for engineering defects on a carboxylate-based metal organic framework (MOF) catalyst is described. The process includes providing a carboxylate-based MOF catalyst; and heating the carboxylate-based MOF catalyst in an inert gas atmosphere at temperatures between about 150° C. and about 900° C.

Aguirrezabal, Iker↗
DOE OSTI2023

Thermally stable porous catalyst systems and methods to produce the same

This disclosure provides compositions and methods directed to thermally stable catalyst systems, which display stable physical properties and/or stable catalytic properties after thermal pretreatment at a temperature in the range of about 600° C. to about 1000° C. The catalyst systems include metal particles which contain a stable metal and a catalytic metal deposited on a porous support. Embodiments of the disclosure include catalyst systems that can be used in high temperature applications such as the hybrid sulfur cycle. The hybrid sulfur cyclic is an elevated temperature and high acid reaction that may be conducted using concentrated sulfuric acid heated to 800° C. Embodiments of the disclosure can provide thermally stable catalysts and methods to produce thermally stable catalysts that remain active for at least 80 hours' exposure to these harsh conditions.

Monnier, John↗
DOE OSTI2025

Multimetallic Metal-Organic Frameworks as Heterogeneous Catalysts for Gas Phase Hydroformylation and Hydrogenation Reactions

This project focused on the development bimetallic metal-organic frameworks (MOFs) as gas phase heterogeneous catalysts for hydrogenation and hydroformylation reactions. MOFs are a new class of hybrid inorganic/organic materials that are highly crystalline, with structures consisting of metal nodes of specific geometries connected by organic linkers. Although there have been a number of studies of catalysis at MOF nodes in solution, there is little experimental data in the literature for gas phase reactions despite the fact that industrial heterogeneous catalysis on MOFs is more economically viable than homogeneous catalysis. The use of MOFs as heterogeneous catalysts presents the unique opportunity to carefully control the composition, geometry and ensemble sizes of the active sites, which are all critical factors for the rational design of new catalysts. Specific objectives of the project are as follows: (1) to tailor the geometry, composition and ensemble size of the active sites; (2) to understand how the adsorption of molecules at metal sites can be modified by interactions with a neighboring metal site; (3) to determine how oxidation states of the metal change during reaction and how these states can be modified by metal-metal electronic interactions; and (4) to elucidate reaction mechanisms and intermediates. For these studies, we have chosen to investigate selective hydrogenation of hydrocarbons and hydroformylation, which are industrially relevant reactions. Our interdisciplinary team of Chen, Shustova and Vogiatzis/Henkelman provides critical expertise in novel MOF synthesis (Shustova), atomic-scale surface science and catalysis (Chen) and computational studies of reaction mechanisms (Vogiatzis/Henkelman) that are necessary for the development of these catalysts. We believe that this work will lead directly to the rational design of new catalysts that are versatile, highly active/selective and suitable for industrial processes.

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

Chapter 3: Nanostructured Iron Oxide Hybrid Composites as Heterogeneous Fenton-Like Catalyst for Remediation of Persistent Organic Pollutants

In water purification research and technologies, heterogeneous Fenton catalysts are evolving as an excellent material recently. A summary of present research on heterogeneous Fenton/Fenton-like processes is essential for developing novel and high-efficiency organic wastewater treatment methods. In this chapter, we discussed the basics of Fenton reactions taking the example of iron oxides and their different composites, such as bimetallic composites, composites with carbon compounds, and Fe metal-organic frameworks (MOFs). The important operating parameters (solution pH, H 2 O 2 dosage, amount of catalyst used, and reaction temperature) in heterogeneous Fenton-like reactions are discussed. Strategies to increase the rate and activities of heterogeneous Fenton catalysts by using energy sources are presented. The mechanistic aspects of heterogeneous Fenton processes and reusability of catalysts along with their application in real wastewater plants are summarized and discussed. Finally, we concluded with the scope and future prospects of heterogeneous Fenton catalysis research to motivate the readers to construct novel and efficient heterogeneous Fenton/Fenton-like systems for industrial applications.

carbon composites↗
DOE OSTI2026

Theory Guided Fine‐Tune of Strain Effects in Pt Ternary Alloy via Rare Earth Templating: Achieving High Performance PEMFCs Catalysts

The sluggish kinetics and insufficient durability of platinum-based catalysts remain crucial barriers limiting proton-exchange-membrane fuel cells (PEMFCs) deployment. Here, we report a theory-guided synthesis combined with rare-earth templating to realize a previously inaccessible Pt 5 Co-like phase with tailored atomic-scale strain. Guided by density functional theory (DFT) calculations, we identified that a Pt 5 Co-like sublayer can induce a unique mild compressive strain (−1.24%) to the Pt(111) shell and an optimal *OH binding energy shift (ΔE ≈ 0.11 eV). This shift positions the alloy catalyst near the apex of the oxygen reduction reaction activity volcano. This prediction guided the synthesis of ternary alloy Pt 5 (Ce)Co@Pt multilayer nanoparticles, featuring a Ce-stabilized core, a Pt 5 Co-like sublayer, and a Pt-rich shell. This catalyst demonstrates both exceptionally high activity and durability, achieving a mass activity of 2.6 A∙mg Pt −1 in rotating disk electrode testing. In fuel cell membrane electrode assembly tests, Pt 5 (Ce)Co@Pt achieves a current density of 1.9 A∙cm −2 at 0.7 V under heavy-duty vehicle conditions. Remarkably, it maintains 1.2 A∙cm −2 after 1 80 000 AST cycles, doubling the U.S. DOE 2025 target. This work demonstrates a rational design strategy that DFT-guided strain engineering integrates with rare-earth templating to advance Pt-based catalysts for fuel cell applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Regulating catalyst and ionomer interactions to promote oxygen transport in fuel cells

The cost of proton exchange membrane fuel cells (PEMFCs) has been a major impediment to their widespread commercialization. Reducing platinum (Pt) usage in PEMFC represents an essential step in lowering the cost. However, decreasing Pt loading in the cathode catalyst layer (CCL) often leads to a significant increase in the local oxygen transport resistance (R Local ), which not only slows the oxygen reduction reaction but also causes a higher polarization overpotential. The poisoning of Pt by perfluorosulfonic acid ionomers also becomes more predominant at low Pt loadings. Therefore, regulating catalyst and ionomer interactions by optimizing their interface in the CCL is crucial to improving PEMFC performance. Here, in this review, the strategies of improving oxygen transport by controlling Pt-ionomer interactions and interfaces through catalyst design, ionomer structure, and incorporation of additives are summarized. Finally, perspectives on future optimization of catalyst and ionomer interactions are proposed.

25 ENERGY STORAGE↗
DOE OSTI2023

Large-scale synthesis of metal/nitrogen Co-doped carbon catalysts for CO 2 electroreduction

In this work, we report a facile approach for synthesizing M–N–C catalysts (M = Co, Fe, Ni) at a commercial scale without employing organic solvents. Our characterization efforts indicate that single atomic catalysts with high surface areas were successfully obtained. Electrochemical measurements demonstrate that, among the three synthesized catalysts, Ni–N–C exhibits the highest performance in the electrochemical CO2 reduction reaction (CO 2 RR) to carbon monoxide (CO), affording 80% Faradaic efficiency (FE) of CO production at –0.49 V RHE with a turnover frequency (TOF) of 57,379 h –1 . Large-scale synthesis coupled with high performance allows moving forward with the practical implementation of M–N–C catalysts for industrially relevant CO 2 RR.

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

Catalysts by pyrolysis: Direct observation of chemical and morphological transformations leading to transition metal-nitrogen-carbon materials

Transition metal-nitrogen-carbon materials (M-N-C catalysts) are promising electrocatalysts in polymer electrolyte fuel cells (PEFCs) and electrolyzer applications. High temperature treatment in inert atmosphere (pyrolysis) is the essential, most common method for the synthesis of M-N-C catalysts and critical to achieve high electrocatalytic activity and electronic conductivity. To this day, despite many uses and successful implementations in materials manufacturing, pyrolysis has been an entirely empirical technology, with process control and optimization relying exclusively on “Edisonian” approach. The knowledge gap in the mechanism about how the precursor is being transformed into catalysts hinders further development of the M-N-C catalysts regardless of the precursor class and processing protocols. In this work, we probed the morphological evolution and chemical transformation of a nitrogen-containing charge transfer organic salt, mixed with transition metal (iron) salt and amorphous silica powder (precursor) during the pyrolysis process via a combination of in situ synchrotron and laboratory-based diagnostic techniques. The pyrolysis process is found to be divided into three stages. During a controlled temperature ramp, the selected organic N-C precursor (nicarbazin) began melting and decomposing just below 400 °C, forming a certain number of micrometer-scale pores and pathways. With increase in temperature from 400 °C to 900 °C, amorphous carbon domains started forming, and reduced (metallic) iron nanoclusters appeared, being dispersed uniformly throughout the carbonaceous matrix. When temperature advanced above 900 °C, graphitization of carbon commenced, associated with appearance and evolution of atomically dispersed metal-nitrogen moieties in the carbonaceous matrix. As the graphitization advanced further, a secondary process of agglomeration of metal nanoparticles occurred. Multi-analytical technique observations conducted here provide a base for rational design and optimization of M-N-C electrocatalysts via pyrolysis.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Impact of Hydration on Supported V 2 O 5 /TiO 2 Catalysts as Explored by Magnetic Resonance Spectroscopy

Supported vanadium oxide catalysts are important industrial materials for a wide array of chemical transformations. The condition of surface hydration is of particular interest as a reflection of the state of a freshly manufactured catalysts prior to its activation in catalytic reactors or under conditions of photocatalysis where surface vandia are exposed to moisture. Under such conditions, the surface vanadia species undergo structural changes as evidenced by 51 V MAS NMR in this study. For low surface vanadia densities on titania, a modest trend towards the formation of dimeric and oligomeric vanadia species was observed under hydrated conditions when compared to the corresponding dehydrated catalyst, which contains a large abundance of monomeric vanadia species. The incorporation of tungsten oxide to the V 2 O 5 /TiO 2 catalyst with low surface vanadia density, however, is found to better stabilize the surface vanadia species on the titania support upon hydration than its tungsta-free counterpart. This stabilization is not an intrinsic property of more extensively oligomerized surface vanadia species in the presence of tungsten oxide, evidenced by conditions of high concentrations of surface vanadia oligomers on titania that exhibit dramatic structural changes upon hydration. At high surface vanadia coverage under hydrated environments, the simultaneous observation of crystalline V 2 O 5 nanoparticles and a mobile phase of surface vanadia species is apparent, where vanadia species are dissolved in the thin hydration layer on the titania support. These new findings have broad implications on the behavior of other metal oxide species on high surface oxide supports under hydrated conditions.

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

Selective and Stable In-Promoted Fe Catalyst for Syngas Conversion to Light Olefins

A selective and stable alumina-supported In-promoted Fe catalyst (10 mol % In based on Fe) was discovered for converting syngas (2:1 H 2 /CO ratio) to olefins with high selectivity (45% with CO 2 included) and a remarkable stability (72 h run) at a CO conversion of 10% at 400 °C and 5 bar. The X-ray photoelectron spectroscopy results indicated that incorporating In into Fe catalysts changed the chemical bonding state of Fe and Fe/In composition near the surface layers, which affected the catalytic reactivity. Steady-state isotopic transient kinetic analysis showed that more stable CHx fragments are present on the catalyst surface when incorporating In into Fe, which can promote C–C coupling reaction toward olefins. Our study demonstrates that introducing In into Fe catalysts on Al 2 O 3 support can lower CO activation abilities. It has more impacts on lowering hydrogenation activity, which permits more C–C couplings and like of “ene” hydrogenation. Furthermore, weakening CO adsorption both in terms of sites and strength encouraged CO toward hydrocarbons rather than CO 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Esters are often produced as unwanted byproducts during the catalytic upgrading of ethanol to diesel fuel precursors through Guerbet coupling. Removal of esters from the product stream is important to prevent the loss of downstream catalyst activity from ester-derived carboxylic acids. In this work, we studied ester hydrogenolysis to the parent alcohols as a viable route for enhanced diesel fuel production. Specifically, we investigated the reduction of hexyl acetate in butanol over ZrO 2 -supported Ni, Co, Cu, Rh, Pd, and Pt catalysts, where Cu/ZrO 2 was the most selective catalyst for the hydrogenolysis of hexyl acetate into hexanol and ethanol. Thermodynamic analysis reveals that a 90% alcohol yield can be obtained at 200 °C, 30 bar, and a relatively high H 2 :hexyl acetate molar ratio of 480:1. Experimentally, an alcohol yield of 88% yield was obtained with a 10 wt % Cu/ZrO 2 catalyst at these conditions with a residence time of 5.4 h kg cat kmol gas –1 . Catalytic tests on the support revealed that ZrO 2 catalyzes the transesterification reaction between hexyl acetate and butanol. However, only the Cu sites can catalyze the hydrogenolysis of the esters into the final alcohols. We developed a kinetic model for our experimental results, which shows that the transesterification and hydrogenolysis reactions run at two different timescales, the former being 10 times faster than the latter. Data regression has been used to develop a model to predict the mole fraction distribution of ester hydrogenolysis products over a wide range of contact times. Cu/ZrO 2 loses half its catalytic activity after 80 h of time on stream. Modeling of deactivation data reveals that the ZrO 2 support conserves a residual activity due to external active sites, while active sites over the Cu surface deactivate at different rates. Furthermore, the catalytic conversion of esters into their parent alcohols is relevant to the production of surrogate liquid fuels since alcohols can be bimolecularly dehydrated to produce a blend of ethers with diesel fuel-like properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Ripening of Rh Nanoparticle Catalysts in Reverse Water–Gas Shift via a Data-Driven Model Combining Physics, Theory, and Experiment

Degradation via sintering is an ongoing challenge that impedes the broad commercial success of supported metallic nanoparticle catalysts. To mitigate degradation via informed catalyst design and process operations, here we aim to disambiguate the underlying mechanisms of sintering by combining theory and experiment in a quantitative framework. While mechanistic sintering models exist, they only model a single sintering pathway, even though multiple sintering mechanisms can occur simultaneously or dominate at different stages of the process. Data-driven machine learning models have emerged as a means to represent complex processes through data regression. However, machine learning models have very large data needs and lack mechanistic insights due to their black-box encoding. To develop an interpretive model of catalyst degradation via sintering, we constructed a hybrid model combining mechanistic “physics-based” models and data-driven methods to obtain both reliable predictions and mechanistic insights regarding experimentally observed sintering phenomena. Focusing on nanoparticle sintering in the Rh–TiO 2 catalyst for the reverse water–gas shift (RWGS) reaction, the hybrid model couples a mechanistic term for Ostwald ripening with energy values calculated via density functional theory (DFT) with a parametric, data-driven discrepancy function term for unmodeled mechanisms. The hybrid model is trained using Bayesian inference with data collected from small-angle X-ray scattering (SAXS) in situ experiments wherein average nanoparticle diameter versus time was measured at three relevant operating temperatures. The calibrated hybrid model results show that an Ostwald ripening-only model parameterized with fixed DFT energies does not fully capture the time and temperature dependence of the SAXS-observed sintering kinetics, and that an additional functional contribution, or DFT energy calibration, is required to reconcile simulation and experiment. Analysis of the hybrid-model error confirms that the hybrid model outperforms both the purely mechanistic and purely data-driven alternatives in terms of expected predictive accuracy for time-evolving average particle sizes. Furthermore, the results support the hypothesis that the Ostwald ripening mechanism is less important for explaining the sintering phenomena as operating temperature increases under an assumed fixed DFT parameterization. This could be explained in one of two ways: either latent, unmodeled sintering mechanisms dominate at higher temperatures, or the DFT uncertainty increases with temperature. The proposed modeling approach directly links theory to experiments and simulations via a statistical hybrid modeling framework and can be extended to other catalytic systems to improve predictive models and mechanistic understanding.

Bayesian hybrid modeling↗
DOE OSTI2020

Conversion of Polyolefin Waste to Liquid Alkanes with Ru-Based Catalysts under Mild Conditions

Chemical upcycling of waste polyolefins via hydrogenolysis offers unique opportunities for selective depolymerization compared to high temperature thermal deconstruction. Here, we demonstrate the hydrogenolysis of polyethylene into liquid alkanes under mild conditions using ruthenium nanoparticles supported on carbon (Ru/C). Reactivity studies on a model noctadecane substrate showed that Ru/C catalysts are highly active and selective for the hydrogenolysis of C(sp 3 )–C(sp 3 ) bonds at temperatures ranging from 200 to 250 °C. Under optimal conditions of 200 °C in 20 bar H 2 , polyethylene (average M w ~ 4000 Da) was converted into liquid n-alkanes with yields of up to 45% by mass after 16 h using a 5 wt % Ru/C catalyst with the remaining products comprising light alkane gases (C 1 –C 6 ). At 250 °C, nearly stoichiometric yields of CH 4 were obtained from polyethylene over the catalyst. The hydrogenolysis of long chain, low-density polyethylene (LDPE) and a postconsumer LDPE plastic bottle to produce C 7 –C 45 alkanes was also achieved over Ru/C, demonstrating the feasibility of this reaction for the valorization of realistic postconsumer plastic waste. By identifying Ru-based catalysts as a class of active materials for the hydrogenolysis of polyethylene, this study elucidates promising avenues for the valorization of plastic waste under mild conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

CO oxidation over a ligand coordinated single site Rh catalyst: identification of the active complex

Single atom catalysis has evolved as a promising strategy to enhance atom utilization efficiency, lower reaction temperatures, and control reaction pathways in heterogeneous catalytic reactions. An important challenge using supported single atom catalysts is the stability of metal single atoms during reactions. Here, we present an approach to stabilize single rhodium atoms on a titania support via a metal–ligand coordination strategy. We explore the reaction activity and mechanism of CO oxidation, as well as the stability under oxidative reaction conditions. Kinetic studies suggest that, with an excess of oxygen in the feed gas, oxygen activation is more facile on defective titania surfaces than on pristine titania surfaces. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis shows that on the pristine titania surface, the 1,10-phenanthroline-5,6-dione (PDO) coordinated Rh catalyst (Rh–PDO/TiO 2 ) catalyzes CO oxidation via the formation of carbonate-like species, which is similar to what occurs on Rh nanoparticle catalysts. However, on the defective titania surface, no carbonate species form for Rh–PDO/def-TiO 2 . The supported Rh–ligand catalysts are also shown to be very stable in such a reaction environment at elevated temperatures, potentially allowing for wide applications.

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

A High‐Rate Li–CO 2 Battery Enabled by 2D Medium‐Entropy Catalyst

Abstract Lithium‐air batteries based on CO 2 reactant (Li–CO 2 ) have recently been of interest because it has been found that reversible Li/CO 2 electrochemistry is feasible. In this study, a new medium‐entropy cathode catalyst, (NbTa) 0.5 BiS 3 , that enables the reversible electrochemistry to operate at high rates is presented. This medium entropy cathode catalyst is combined with an ionic liquid‐based electrolyte blend to give a Li–CO 2 battery that operates at high current density of 5000 mA g −1 and capacity of 5000 mAh g −1 for up to 125 cycles, far exceeding reported values in the literature for this type of battery. The higher rate performance is believed to be due to the greater stability of the multi‐element (NbTa) 0.5 BiS 3 catalyst because of its higher entropy compared to previously used catalysts with a smaller number of elements with lower entropies. Evidence for this comes from computational studies giving very low surface energies (high surface stability) for (NbTa) 0.5 BiS 3 and transmission electron microscopystudies showing the structure being retained after cycling. In addition, the calculations indicate that Nb‐terminated surface promotes Li–CO 2 electrochemistry resulting in Li 2 CO 3 and carbon formation, consistent with the products found in the cell. These results open new direction to design and develop high‐performance Li–CO 2 batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Advancing Photo(Electro)Chemical Water Splitting: The Promise of Atomically Dispersed Single‐, Dual‐, and Alloy‐Site Catalysts

Single-atom catalysts (SACs) have rapidly gained prominence as an emerging class of electrocatalysts for water splitting, owing to their uniform and precisely defined active sites. By maintaining uniform reaction pathways, SACs minimize the formation of unwanted byproducts, thus exhibiting extremely high selectivity and atomic efficiency. A key determinant of SAC performance lies in the interfacial interaction between the isolated metal atoms and the supporting material under strong metal–support coordination, which is vital for maintaining long-term activity. However, despite these benefits, reproducibly synthesizing SACs with high metal loadings while retaining uniform dispersion remains a significant challenge. To address the intrinsic challenges of SACs, recent research has expanded into dual-atom catalysts (DACs) and single-atom alloy catalysts (SAACs), providing synergistic active sites and combining the benefits of SACs with bimetallic systems. Furthermore, this review systematically explores the latest advancements in synthesis methods and innovations for SACs for electrochemical water splitting. Additionally, it examines the evolution of catalyst design, emphasizing the unique structural and electronic characteristics of single-site, dual-site, and alloyed SAC systems and highlighting their critical roles in accelerating water-splitting reaction kinetics as well as the prevailing challenges and outlining promising directions for advancing hydrogen production via water electrolysis.

08 HYDROGEN↗