Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “catalyst characterization”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Catalytic degradation of waste rubbers and plastics over zeolites to produce aromatic hydrocarbons

Catalytic conversion of waste rubbers and plastics into aromatic hydrocarbons is a promising approach to waste management and energy recovery. In the present study, acidic HY zeolites were supported by cobalt, iron, and zirconium, and the catalysts were characterized by powder X-ray diffraction, nitrogen adsorption-desorption, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy, and pyridine-Fourier transform infrared spectroscopy. Here, the catalytic degradation of waste polybutadiene rubbers (BR) was conducted to investigate the degradation mechanism and evaluate the catalytic activity of supported zeolites. Experimental results indicated that HY loaded by zirconium and iron led to a higher content of Lewis acid sites as opposed to cobalt supported one. Compared with the non-catalytic pyrolysis of BR, the zirconium supported HY (Zr/HY) led to a 10-fold increase in aromatic hydrocarbons production with a distinctively high selectivity of 97.9%. A series of waste polymers including waste tires (WT), polyethylene (PE), polycarbonate (PC), and BR, were subjected to catalytic pyrolysis to explore the effects of polymer type on aromatic hydrocarbons generation, and BR was the most effective substrate, with yield enhancement reaching 2.4 over Zr/HY. Catalytic co-pyrolysis of waste rubbers and plastics was conducted to probe the effect of polymer structure on aromatic hydrocarbons formation, where a significant synergistic effect was observed in the PE co-fed with PC run.

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

Multi-technique characterization of spray coated and roll-to-roll coated gas diffusion fuel cell electrodes

Here this work reports the characterization of catalyst layer (CL) structure and composition for a set of gas-diffusion electrodes (GDEs) fabricated by different coating methods with the goal of developing a better understanding of CL processing-structure-property-performance relationships. The CL coating techniques used in this study were ultrasonic spray coating, and two roll-to-roll (R2R) methods - gravure and slot die. Scanning transmission electron microscopy (STEM) coupled with X-ray energy dispersive spectroscopy (EDS) analysis of GDE cross-sections provided bulk information, while scanning electron microscopy (SEM) with EDS and X-ray photoelectron spectroscopy (XPS) were used to investigate the near surface and surface composition of the CLs that will be in direct contact with the membrane once the membrane electrode assembly (MEA) is constructed. This study demonstrates that common quantification parameters, namely the F:Pt ratio extracted from cross-sectional STEM-EDS maps and top-down CL measurements with SEM and XPS, along with roughness parameters quantified from SEM micrographs are useful parameters in explaining and potentially predicting performance trends. Additionally, it highlights the importance of understanding key CL surface properties for advancing the manufacturability of high-performance components for polymer electrolyte membrane (PEM) technologies.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2018

Hydrothermal synthesis of core-shell ZSM-5/SAPO-34 composite zeolites and catalytic performance in methanol-to-aromatics reaction

A series of core-shell ZSM-5/SAPO-34 composite catalysts with different molar ratios were synthesized using hydrothermal method, and their catalytic performance was tested for the conversion of methanol-to-aromatics. The catalysts were characterized by means of XRD, SEM, NH{sub 3}-TPD and N{sub 2} adsorption-desorption analysis. The results showed that pristine SAPO-34 showed much lower selectivity to aromatics due to its narrow cage structure and lower acid sites. However, with increasing ZSM-5/SAPO-34M ratio, composite zeolite showed higher selectivity to aromatics. As the molar ratio was up to two, the selectivity to aromatics was even higher than that of pristine ZSM-5, indicating that core-shell composite zeolites with hierarchical structure and moderate acid sites were favored for methanol to aromatics. Meanwhile the optimum reaction condition for high yield of aromatics is determined to be 450 °C and 1.5 h{sup −1}(WHSV).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Biosynthesis of the palladium/sodium borosilicate nanocomposite using Euphorbia milii extract and evaluation of its catalytic activity in the reduction of chromium(VI), nitro compounds and organic dyes

Highlights: • Green synthesis of Pd/sodium borosilicate nanocomposite using Euphorbia milii aqueous extract. • Characterization of catalyst by FT-IR, XRD, FESEM, EDS, TEM and elemental mapping. • Catalytic reduction of Cr(VI), 2,4-DNPH, 4-NP, CR, MO and MB by Pd/sodium borosilicate nanocomposite. - Abstract: For the first time, a green method is developed to prepare palladium/sodium borosilicate nanocomposite by using aqueous extract of the leaves of Euphorbia milii as bioreducing and stabilizing agent. The immobilization of Pd NPs on the surface of the sodium borosilicate glass was established by several instrumental analysis including X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), EDS elemental dot maps and transmission electron microscopy (TEM). The green synthesized nanocatalyst exhibited excellent performance in the reduction of the chromium (VI) (Cr(VI)), nitro compounds such as 2,4-dinitrophenylhydrazine (2,4-DNPH) and 4-nitrophenol (4-NP) and some organic dyes containing Congo red (CR), Methyl orange (MO), and Methylene blue (MB). The biosynthesized heterogeneous catalyst was easily recovered and reused at least in 5 consecutive reactions with no losing of its performance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Silver-loaded ZnO/ZnFe2O4 mesoporous hollow spheres with enhanced photocatalytic activity for 2,4-dichlorophenol degradation under visible light irradiation

Highlights: • Visible-light-driven ZnO/ZnFe{sub 2}O{sub 4}/Ag spheres were successfully synthesized. • ZnO/ZnFe{sub 2}O{sub 4}/Ag spheres have unique mesoporous hollow structures. • ZnO/ZnFe{sub 2}O{sub 4}/Ag spheres exhibit excellent photodegradation of 2,4-dichlorophenol. • ZnO/ZnFe{sub 2}O{sub 4}/Ag spheres are reusable with the aid of a magnet. - Abstract: Silver-loaded ZnO/ZnFe{sub 2}O{sub 4} (ZnO/ZnFe{sub 2}O{sub 4}/Ag) mesoporous hollow spheres were synthesized via a layer-by-layer technique followed chemical reduction method. The structures and morphologies of the as-prepared catalysts were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and N{sub 2} adsorption/desorption porosimetry. The photodegradation activities of ZnO/ZnFe{sub 2}O{sub 4}/Ag mesoporous hollow spheres toward 2,4-dichlorophenol were investigated under UV and visible light irradiation. The experimental results indicated that our mesoporous hollow spheres exhibited much higher photodegradation activities than P25 for the loading of silver particles, the bands matching and the unique structures. There exists an optimal loading dosage of silver particles. Too high or too low loading will reduce the photodegradation activities of ZnO/ZnFe{sub 2}O{sub 4}/Ag mesoporous hollow spheres. The possible mechanism behind was proposed. Noteworthily, the ZnO/ZnFe{sub 2}O{sub 4}/Ag mesoporous hollow spheres are reusable with the aid of a magnet, which is cost effective.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Tuning the Electrocatalytic Oxygen Reduction Reaction Activity of PtCo Nanocrystals by Cobalt Concentration with Atomic-Scale Understanding

The development of a suitable catalyst for the oxygen reduction reaction (ORR) – the cathode reaction of proton exchange membrane fuel cells (PEMFC) – is necessary to push this technology towards widespread adoption. There have been substantial efforts to utilize bimetallic Pt-M alloys that adopt the ordered face-centered tetragonal (L10) phase in order to reduce the usage of precious metal, enhance the ORR performance, and improve catalyst stability. In this work, monodisperse Pt-Co nanocrystals (NCs) with well-defined size (4-5 nm) and cobalt composition (25-75 at%) were synthesized via colloidal synthesis. The transformation from the chemically disordered A1 (face-centered cubic, fcc) to the L10 phase was achieved via thermal annealing using both a conventional oven and a rapid thermal annealing process. The structure of the Pt-Co catalysts was characterized by a variety of techniques, including transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy in high-angle annular dark-field scanning transmission electron microscopy (STEM-EDS), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of annealing temperature on the composition-dependent degree of ordering, and subsequent effect on ORR activity is described. This work provides insights regarding the optimal spatial distribution of elements at the atomic level to achieve enhanced ORR activity and stability.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Molecular Design of Supported MoO x Catalysts with Surface TaO x Promotion for Olefin Metathesis

A series of supported 3% MoOx catalysts were synthesized by incipient-wetness impregnation of 5%-15% TaO x surface modified γ-Al 2 O 3 support. The catalysts were characterized by in situ spectroscopies (DRIFTS, Raman, UV-vis, XAS) and multiple chemical probes (C 2 H 4 /C 4 H 8 titration, C 3 H 6 -TPSR, steady state propylene metathesis, NH 3 -IR adsorption). The supported tantalum oxide phase was present as surface TaO x sites on the γ-Al 2 O 3 support that capped that Al 2 O 3 surface hydroxyls. The change in available surface hydroxyls caused the subsequent anchoring of MoOx species to occur at different surface hydroxyls. This shifted the anchoring of MoO x species from basic (Al-OH) to neutral (Al 2 -OH) to more acidic (Al 3 -OH) surface hydroxyls as well as perturbation of the remaining alumina surface hydroxyls by the surface TaO x sites. The TaO x surface modified γ-Al 2 O 3 support increased the number of activated surface MoO x sites (Ns) by ~6x and the TOF by ~10x resulting in an increased activity of ~60x. In conclusion, It was found that the specific anchoring surface hydroxyls rather than the extent of oligomerization of the surface MoO x sites control the number of activated MoO x sites and TOF for propylene metathesis. No relationship between the nature of the surface Lewis/Brønsted acid sites and Ns and TOF were found to be present.

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

Impact of Carbon Support Structure on the Durability of PtCo Electrocatalysts

High performing, low-Pt content fuel cell membrane electrode assemblies (MEAs) are critical to the economic viability of proton exchange membrane fuel cells (PEMFCs) for the transportation industry. Considerable research has been conducted to reduce the Pt content in fuel cells, leading to the development of transition metal alloys, such as Platinum-Cobalt (PtCo). The degree of degradation of PtCo catalysts can be impacted by the catalyst metal itself and its interactions with the carbon support. Several low-loaded PtCo MEAs were fabricated, with various combinations of porous and solid carbon cathode catalyst supports. The MEAs were subjected to an accelerated stress test (AST), and the catalyst degradation characterized using electrochemical, X-ray scattering, and electron microscopy techniques. Porous supports retain more of their electrochemically-active surface area (ECSA) and demonstrate higher performance after the AST. Overall, this is believed to be due to the ability of the porous supports to trap the metal particles within the pores, slowing their dissolution/precipitation, and agglomeration.

25 ENERGY STORAGE↗
DOE OSTI2021

Impact of Carbon Support Structure on the Durability of PtCo Electrocatalysts

High performing, low-Pt content fuel cell membrane electrode assemblies (MEAs) are critical to the economic viability of proton exchange membrane fuel cells (PEMFCs) for the transportation industry. Considerable research has been conducted to reduce the Pt content in fuel cells, leading to the development of transition metal alloys, such as Platinum-Cobalt (PtCo). The degree of degradation of PtCo catalysts can be impacted by not only the composition and morphology of the catalyst particle itself, but also its interactions with the carbon support. In this study several low-PtCo MEAs were fabricated, with various combinations of porous and solid carbon cathode catalyst supports. The MEAs were subjected to an accelerated stress test (AST), and the catalyst degradation characterized using electrochemical, X-ray scattering, and electron microscopy techniques. Porous supports retain more of their electrochemically-active surface area (ECSA) and demonstrate higher performance after the AST. This is believed to be due to the ability of the porous supports to trap the metal particles within the pores, slowing their dissolution/precipitation, and agglomeration. However porous supports also exhibit greater increases in transport resistance probably associated with enhanced Co leaching under the AST conditions.

25 ENERGY STORAGE↗
DOE OSTI2020

Hydrogen Energy: Production and Utilization for a Green Economy [Slides]

The scope of the presentation includes: 1. Introduce high-level aspects of hydrogen fuel systems; and, 2. Showcase research addressing relevant challenges: Proton exchange membrane fuel cells (PEMFCs) (Subzero temperature applications and AFM characterization of catalyst layers); and, Non-precious-metal hydrogen evolution catalysts).

08 HYDROGEN↗
DOE OSTI2023

A Brief Review of Sylgard 184

This paper will explore applications and functionality of the Dow material Sylgard 184. Pure Sylgard 184 is a “Two-part, clear, 10:1, RT and heat cure, good strength, UL and Mil Spec” material that has good dielectric properties. According to the Technical Data Sheet, Sylgard 184 has a base viscosity of 511 cP, mixed viscosity of 3500 cP, and a work time of 1.5 hours. The cured mate rial has a Shore A hardness of 43, a tensile strength of 980 PSI, and a dielectric strength of 500 volts/mil.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development and Commercialization of a Nanosegrated Oxygen Evolution Reaction Electrocatalyst (CRADA)

This collaborative project leverages advanced characterization tools, catalyst treatment and electrochemical testing capabilities at LBNL to help commercialize a bimetallic nanosegrated catalysts for oxygen evolution reaction in proton-exchange membrane water electrolyzers. This project also has three industrial partners who are involved in catalyst scale-up synthesis, large electrode fabrication and large electrode electrochemical testing. This project investigates a broad range of topics including electrocatalysis, ink rheology and electrode fabrication and testing. This knowledge could help bridge the performance and durability gap from laboratory-developed materials (such as electrocatalysts) to applications in commercial devices. The research results also bring fundamental understanding of possible degradation mechanisms that occur under extremely oxidative potentials including material and morphological changes. The project will help accelerate the deployment of proton-exchange membrane water electrolyzers. The public benefits could include creating jobs and increasing public awareness of potential clean technologies for green hydrogen production. Ultimately, the project will help national wide effort of flighting climate change and achieving carbon neutrality by 2050.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2025

Microwave-Assisted Activation of Mo/HZSM5 in Methane Dehydroaromatization

Natural gas flaring is a significant challenge for oil and gas producers. One viable option to mitigate flaring is the conversion of natural gas into valuable chemicals. Applying microwave energy to heterogenous catalyst materials offers advantages in terms of higher rates and product selectivities in comparison to traditional thermal systems which can be designed for on-demand chemical production in modular reactor systems. Methane dehydroaromatization (MDHA) produces transportable, liquid aromatic products directly from natural gas, which is ideal for remote production but is hindered by low thermodynamic yields and rapid deactivation. The stability and performance of the Mo/ZSM5 catalyst is often determined by the state and nature of Mo in the catalyst, which in turn is dictated by the temperature and gaseous environment during catalyst activation. In this study, the Mo/HZSM5 catalyst was activated under three different heating modes (thermal, microwave E-field, and microwave H-field) and four different gas environments (CO, He, CH4+H2, and H2). All the activated catalysts were characterized using different tools and performance evaluated in MDHA.

methane dehydroaromatization↗
DOE OSTI2025

Direct Air Reactive Capture and Conversion for Utility-Scale Energy Storage (Final Report)

This final report for FEW0277 summarizes the work performed over the project performance period of October 2021 – March 2025. This project was funded under the “Reactive Capture and Conversion R&D” lab call released in FY2021. The goal of the project was to develop dual-function materials and process for capturing CO 2 from the atmosphere and converting it into CH 4 . The work was organized into four parallel tracks in 1) direct air capture materials synthesis and characterization, 2) catalysts for CO 2 conversion, 3) mechanistic investigations via ab initio simulations, and 4) process modeling, technoeconomic analysis, and lifecycle assessment. The project was split into two budget periods. The first budget period focused on development of amine-based materials, due to their known performance for CO 2 direct air capture and their potential to act synergistically with metal catalysts to enable a low-temperature methanation pathway. The second budget period focused on development of alkali-based materials and a simulated-moving-bed process for high conversion catalytic reduction of captured CO 2 to CH 4 . All project milestones were completed during the project performance period and are summarized in this report. Our work resulted in publication of eight peer-reviewed manuscripts, one patent application, and numerous presentations given at domestic and international conferences and invited academic department seminars.

03 NATURAL GAS↗
DOE OSTI2021

Nanowire-Based Materials as Coke-Resistant Catalyst Supports for Dry Methane Reforming

In this paper, nanowire-supported catalysts loaded with nickel are shown to be coke resistant compared to nanoparticle-supported catalysts. Specifically, Ni-loaded titania-based nanowire catalysts were tested with the dry methane reforming process in a laboratory-scale continuous packed-bed atmospheric reactor. The CO 2 conversion rate stayed above 90% for over 30 h on stream under coke-promoting conditions, such as high flow rates, low temperatures, and a high ratio of CH 4 to CO 2 . The coke (C x H y , x>>y) on the spent catalyst surface for both nanowire- and nanoparticle-supported catalysts was characterized by TGA, temperature-programmed reduction (TPR), and electron microscopy (SEM/TEM/EDS), and it was revealed that the types of carbon species present and their distribution over the morphology-enhanced materials played a major role in the deactivation. The CO 2 conversion activity of Ni supported on titania nanoparticles was reduced from ~80% to less than 72% in 30 h due to the formation of a graphitic coke formation. On the other hand, Ni particles supported on nanowires exhibited cube-octahedral morphologies, with a high density of non- (111) surface sites responsible for the increased activity and reduced graphitic coke deposition, giving a sustained and stable catalytic activity during a long time-on-stream experiment.

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

CO Oxidation Catalyzed by Au Dispersed on SBA-15 Modified with TiO2 Films Grown via Atomic Layer Deposition (ALD)

It has been established that gold, when in nanoparticle (NP) form and in contact with reducible oxides, can promote oxidation reactions under mild conditions. Here, we report results from our exploration of the catalytic oxidation of carbon monoxide using catalysts where Au NPs were combined with thin titanium oxide films deposited on SBA-15 using atomic layer deposition (ALD). Both orders of deposition, with TiO2 added either before or after Au dispersion, were tested for two titania film thicknesses amounting to about half and full TiO2 monolayers. The resulting catalysts were characterized using various techniques, mainly electron microscopy and N2 adsorption–desorption isotherms, and the kinetics of the oxidation of CO with O2 were followed using infrared absorption spectroscopy. A synergy between the Au and TiO2 phases as it relates to the bonding and conversion of CO was identified, the tuning of which could be controlled by varying the synthetic parameters. The ALD of TiO2 films proved to be an effective way to maximize the Au-TiO2 interface sites, and with that help with the activation of molecular oxygen.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗