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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 OSTI2015

Measuring the Noble Metal and Iodine Composition of Extracted Noble Metal Phase from Spent Nuclear Fuel Using Instrumental Neutron Activation Analysis

Mass quantities of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis (NAA). Nuclide presence is predicted using fission yield analysis, and mass quantification is derived from standard gamma spectroscopy and radionuclide decay analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. Lastly, the implications of the rapid analytic speed of instrumental NAA are discussed in relation to potential nuclear forensics applications.

Palomares, R. I.↗
DOE OSTI2025

Sustainable recovery of critical metals from spent lithium-ion batteries through gluconic acid-based bioleaching: Techno-economic analysis, life cycle assessment and process optimization

Recycling spent lithium-ion batteries (LIB) could potentially bridge the ever increasing supply and demand gap for critical metals and simultaneously facilitate the management of hazardous battery waste. This study investigated the optimization of gluconic acid-based bioleaching technology through design of experiments (DOE), combined with techno-economic analysis (TEA), and life cycle assessment (LCA) with the aim of maximizing the net present value (NPV) and minimizing global warming impacts of the process. Biolixiviant containing predominantly gluconic acid produced by the genetically engineered (ΔpstS, P 112 :mgdh) Gluconobacter oxydans B58 through fermentation using non-recyclable paper as a growth substrate was used for the LIB leaching. At optimal bioleaching conditions of gluconic acid (160 mM), leaching time (2.5 h), reducing agent FeSO 4 to metal, i.e., cobalt (Co), nickel (Ni) and manganese (Mn), mole ratio (0.88), temperature (55 °C) and pulp density (2.5 %), the leaching efficiency was 87 % 72 %, 94 %, and 88 % for Co, Ni, Mn and lithium (Li), respectively. TEA analysis confirmed that bioleaching plant with an annual black mass processing capacity of 10,000 metric tons and plant life of 30 years would be economically viable with an NPV and profit margin of $136 million and 11 %, respectively. The predicted carbon footprint of gluconic acid-based bioleaching for recovering 1 kg of Co (13.2 kg of CO 2 eq.) is lower compared to that of most state-of-the-art leaching technologies. Moreover, gluconic acid-based bioleaching effectively recovered target metals when tested for different black mass chemistries.

Bioleaching↗
DOE OSTI2019

Development of Fe-based oxygen carrier using spent FCC catalyst as support for high temperature chemical looping combustion

Chemical looping combustion is based on the transfer of oxygen from air to fuel by means of an oxygen carrier using a metal oxide. This study investigated the development of an oxygen carrier by adding iron to a spent commercial fluid catalytic cracking catalyst (Fe/FCC) and comparing to Fe/Al 2 O 3 , and Fe/SiO 2 oxygen carriers that may be suitable for the high-temperature (1100 °C) process. The FCC material was chosen as a low-cost oxygen carrier. The FCC support strongly modified the reduction behavior of the Fe-based carrier as compared to the Fe/Al 2 O 3 and Fe/SiO 2 carriers. Multicycle studies with CH 4 revealed the FCC support impacted the CO 2 selectivity (13.5%) at 1100 °C to produce more gaseous CO as compared to the 900 °C (89.7%) due to the formation of FeAl 2 O 4 and Fe 2 SiO 4 phases when the Fe 2 O 3 was reduced at 1100 °C. The FeAl 2 O 4 and Fe 2 SiO 4 phases also considerably slowed the CO 2 formation rate on the Fe/FCC oxygen carrier at 1100 °C as compared to the 900 °C reaction tests. The higher-temperature (1100 °C) decreased the oxygen transfer capacity of the Fe/FCC carrier, did not significantly increase the capacity of either the Fe/SiO 2 and Fe/Al 2 O 3 carriers. These results suggest that high-temperatures (1100 °C) may lead to carrier transformations through sintering and agglomeration that significantly reduce the kinetics and performance of the oxygen carrier. This work suggests at higher temperatures, shorter reduction times may be necessary to prevent the formation of these phases and the subsequent deactivation of the carrier for total oxidation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

DEHBA (di-2-ethylhexylbutyramide) gamma radiolysis under spent nuclear fuel solvent extraction process conditions

Di-2-ethylhexylbutyramide (DEHBA) has been presented as part of a hydro-reprocessing solvent extraction system for the co-extraction of uranium and plutonium from spent nuclear fuel. Yet, there remains a lack of quantitative understanding of the impact of chemical environment on the radiation chemistry of DEHBA, especially under conditions expected in real-world solvent extraction processes. Therefore, we have undertaken a systematic investigation into the radiolytic degradation of DEHBA in n-dodecane under fully aerated and biphasic conditions. DEHBA integrity and degradation product formation were measured for both extraction (in contact with 4.0 M HNO 3(aq) ) and stripping (in contact with 0.1 M HNO 3(aq) ) formulations. At the lower acidity the rate of DEHBA/n-dodecane degradation was slow (G = -0.26 ± 0.02 µM J -1 ) whereas at the higher acidity this degradation was about 35% faster (G = -0.35 ± 0.02 µM J-1). Both values were much less than analogous measurements under deaerated conditions. Under continuously aerated conditions, FTIR and ESI-MS measurements identified the two major degradation products, bis-2-ethylhexylamine (b2EHA) and N-(2-ethylhexyl)butyramide (MEHBA), as well as the presence of additional oxidized product species. Solvent system performance was also investigated using uranium extraction and strip distribution ratio measurements. These reports showed that there was only minimal change in uranium extraction and stripping performance with absorbed gamma dose.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Electrodialysis: An effective methodology to purify the leachate of spent Li-ion batteries

The electrification of transportation and the transition of society towards low or net-zero carbon emissions has led to a skyrocketing global demand for Li-ion batteries. After a service life of three to ten years, Li-ion batteries have less than 80 % of their initial capacities and draw near to the end of their lives for practical utilization. Due to potential supply chain shortages and the value embodied in Li-ion batteries, it is imperative to recycle them, to recover the materials, and to improve the circularity and the sustinability of the industry. How to cost-effectively purify spent batteries while reducing time, energy, and waste emissions is a challenge faced by Li-ion battery recyclers. The first electrochemical membrane reactor reported in our group hasa high selectivity towards lower Cu 2+ , Al 3+ and Fe 3+ ions (<5 ppm) and retains >95% of the Ni 2+ , Co 2+ and Mn 2+ ions in the leachate. An advanced electrochemical membrane reactor was developed in this study. Further, not only does the new reactor have the same selectivity as the original reactor, but other advantages including a faster leachate processing rate (up to 10X faster). The advanced reactor can also directly generate acid at the anode side; eliminating the reactor restoration step. The prominent advantages that this electrodialysis technology has over chemical-precipitation methods include: (1) ion recovery efficiencies do not diminish after removing the impurities, Ni 2+ , Co 2+ and Mn 2+ , even at a higher initial Ni 2+ ion concentrations; in comparison, chemical precipitation has Ni 2+ , Co 2+ and Mn 2+ ion recovery efficiencies reduced significantly when the initial Ni 2+ , Co 2+ and Mn 2+ ion concentrations increase. (2) electrodialysis does not change the concentrations of Ni 2+ , Co 2+ and Mn 2+ ions significantly, but chemical precipitation could reduce Ni 2+ and Co 2+ ions to less than half of their initial values. Through electro-dialyzing the leachate, the H 2 evolution reaction mechanism was found to switch from the Volmer-acid Heyrovsky mechanism to the Volmer-alkaline Heyrovsky mechanism at a pH of around 3.7.

25 ENERGY STORAGE↗
DOE OSTI2024

Electrochemical leaching of spent LIBs: Kinetics, novel reactor, and modeling

The use of electrons as main reagent for the recovery and recycling of critical metals from spent lithium-ion batteries (LIBs) is a process electrification strategy that can be used to close the life-cycle loop of LIBs through more sustainable methods. Electrochemical leaching, a process that uses a reductant that is constantly regenerated electrochemically for the leaching of lithium-ion battery black mass (LIBBM), has shown high extraction efficiencies and sustainable scores. However, slow kinetics, reactor design challenges and lack of deeper understanding of the underlying processes are barriers to the optimization, scale-up, and market adoption of this technology. In this paper, a kinetic study and mathematical model for dissolving LIBBM is presented to better understand the underlying mechanisms aiming to reduce the processing time and make predictions for future design and scale-up. The effect of acid and electrochemically mediated reductant concentrations, LIBBM loading, and cathode/reactor designs were explored. As a result, the leaching time was reduced from 7h to under 1h at a pulp density of 73 g/L, without external heating. A novel reactor with parallel baffle electrodes (PBE) was developed, which significantly reduced the leaching time by improving convection in a stirred slurry electrochemical reactor. Dimensionless numbers were deduced from an unsteady state model, which can be used in dimensional analysis for future process design and scale-up.

25 ENERGY STORAGE↗
DOE OSTI2022

The need for speed – Burnup determination of spent nuclear fuel

Here we present the application of a novel analytical approach for high-speed evaluation of burn-up in spent nuclear fuel. This automated online separation–direct analysis method, which simultaneously measures the isotopic compositions and concentrations of Nd, Pu, and U using isotope dilution-inductively coupled plasma mass spectrometry, enables the determination of burnup in as little as 4.5 h per sample with expanded uncertainties as low as 1.2% using as little as 1µg of fuel. We compare the determined burn-up values, sample requirements, and analysis times with an ultra-high precision, in-house developed, methodology which employs multiple analytical techniques to measure the isotopic compositions and concentrations of Nd, Pu, and U yielding burn-up values with expanded uncertainties as low as 0.49% at the 95% confidence level, the lowest reported to date.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2011

Recycling of WEEE: Characterization of spent printed circuit boards from mobile phones and computers

Highlights: > This paper presents new and important data on characterization of wastes of electric and electronic equipments. > Copper concentration is increasing in mobile phones and remaining constant in personal computers. > Printed circuit boards from mobile phones and computers would not be mixed prior treatment. - Abstract: This paper presents a comparison between printed circuit boards from computers and mobile phones. Since printed circuits boards are becoming more complex and smaller, the amount of materials is constantly changing. The main objective of this work was to characterize spent printed circuit boards from computers and mobile phones applying mineral processing technique to separate the metal, ceramic, and polymer fractions. The processing was performed by comminution in a hammer mill, followed by particle size analysis, and by magnetic and electrostatic separation. Aqua regia leaching, loss-on-ignition and chemical analysis (inductively coupled plasma atomic emission spectroscopy - ICP-OES) were carried out to determine the composition of printed circuit boards and the metal rich fraction. The composition of the studied mobile phones printed circuit boards (PCB-MP) was 63 wt.% metals; 24 wt.% ceramics and 13 wt.% polymers; and of the printed circuit boards from studied personal computers (PCB-PC) was 45 wt.% metals; 27 wt.% polymers and ceramics 28 wt.% ceramics. The chemical analysis showed that copper concentration in printed circuit boards from personal computers was 20 wt.% and in printed circuit boards from mobile phones was 34.5 wt.%. According to the characteristics of each type of printed circuit board, the recovery of precious metals may be the main goal of the recycling process of printed circuit boards from personal computers and the recovery of copper should be the main goal of the recycling process of printed circuit boards from mobile phones. Hence, these printed circuit boards would not be mixed prior treatment. The results of this paper show that copper concentration is increasing in mobile phones and remaining constant in personal computers.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry

Highlights: Black-Right-Pointing-Pointer New treatments for CFL are required considering the aim of Directive 202/96/CE. Black-Right-Pointing-Pointer It is shown that most of the mercury introduced into a CFL is in the phosphor powder. Black-Right-Pointing-Pointer Experimental conditions for microwave-assisted sample digestion followed by AAS measurements are described. Black-Right-Pointing-Pointer By washing the glass it is possible to reduce the concentration below legal limits. - Abstract: In this study, spent compact fluorescent lamps were characterized to determine the distribution of mercury. The procedure used in this research allowed mercury to be extracted in the vapor phase, from the phosphor powder, and the glass matrix. Mercury concentration in the three phases was determined by the method known as cold vapor atomic absorption spectrometry. Median values obtained in the study showed that a compact fluorescent lamp contained 24.52 {+-} 0.4 ppb of mercury in the vapor phase, 204.16 {+-} 8.9 ppb of mercury in the phosphor powder, and 18.74 {+-} 0.5 ppb of mercury in the glass matrix. There are differences in mercury concentration between the lamps since the year of manufacture or the hours of operation affect both mercury content and its distribution. The 85.76% of the mercury introduced into a compact fluorescent lamp becomes a component of the phosphor powder, while more than 13.66% is diffused through the glass matrix. By washing and eliminating all phosphor powder attached to the glass surface it is possible to classified the glass as a non-hazardous waste.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Lithium recycling and cathode material regeneration from acid leach liquor of spent lithium-ion battery via facile co-extraction and co-precipitation processes

Highlights: • A novel process for combining Li and cathode material recycling is developed. • Ni, Co and Mn are co-extracted and separated with Li. • Li recovered as Li{sub 2}CO{sub 3} with the purity of 99.2% is achieved. • The spherical cathode material LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} is directly regenerated. - Abstract: A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li{sub 2}CO{sub 3} with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5 M H{sub 2}SO{sub 4}, and the cathode material LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} is miro spherical morphology without any impurities, which can meet with LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Recovery of lithium and cobalt from spent lithium-ion batteries using organic acids: Process optimization and kinetic aspects

Highlights: • Li recovery 99.80%, Co recovery 96.46% in citric acid reductive leaching with H{sub 2}O{sub 2.} • Investigating possibility of bioleaching of LIBs by using 4 organic acids. • Comparing cavitation in ultrasonic agitation with mechanical stirrer. • Co kinetics depends on temperature: both diffusion and chemical reaction controls. •Li kinetics, all temperatures: reagent diffusion through the product layer controls. - Abstract: An environmentally-friendly route based on hydrometallurgy was investigated for the recovery of cobalt and lithium from spent lithium ion batteries (LIBs) using different organic acids (citric acid, Dl-malic acid, oxalic acid and acetic acid). In this investigation, response surface methodology (RSM) was utilized to optimize leaching parameters including solid to liquid ratio (S/L), temperature, acid concentration, type of organic acid and hydrogen peroxide concentration. Based on the results obtained from optimizing procedure, temperature was recognized as the most influential parameter. In addition, while 81% of cobalt was recovered, the maximum lithium recovery of 92% was achieved at the optimum leaching condition of 60 °C, S/L: 30 g L{sup −1}, citric acid concentration: 2 M, hydrogen peroxide concentration: 1.25 Vol.% and leaching time: 2 h. Furthermore, results displayed that ultrasonic agitation will enhance the recovery of lithium and cobalt. It was found that the kinetics of cobalt leaching is controlled by surface chemical reaction at temperatures lower than 45 °C. However, diffusion through the product layer at temperatures higher than 45 °C controls the rate of cobalt leaching. Rate of lithium reaction is controlled by diffusion through the product layer at all the temperatures studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Simultaneous Isotopic Analysis of U, Pu, and Am in Spent Nuclear Fuel by Resonance Ionization Mass Spectrometry

Solid samples of spent nuclear fuel were analyzed for actinide isotopic composition by resonance ionization mass spectrometry. Isotopes of U, Pu, and Am were simultaneously quantified using a new method that removes and/or resolves the isobaric interferences at 238 U/ 238 Pu and 241 Pu/ 241 Am without sample preparation other than cutting and mounting small (~10 μm) samples. Trends in burnup and neutron capture product distributions were correlated with the sampling positions inside the reactor. Overall, the results show the skin effect, in which the core and near-edge regions of a fuel pellet exhibit strong differences in actinide concentrations and isotope distributions due to differences in the neutron energy spectra between the pellet rim and the core. While no elemental concentration measurements were made, the ability to measure the 238 Pu/ 239 Pu ratio in the presence of a 7400× excess of 238 U enabled an estimate of the enhancement in Pu concentration due to the skin effect at the rim of the pellet.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Silver Sulfide and Silver Sulfate as Aging Byproducts and Adsorbents for Gaseous Iodine Capture in Spent Nuclear Fuel Reprocessing

While it is considered a promising adsorbent for radioiodine capture in spent nuclear fuel reprocessing off-gas, silver functionalized silica aerogel (Ag 0 -aerogel) experiences a capacity loss when exposed to other off-gas components (O 2 , H 2 O, NO, and NO 2 ) through a process known as aging. Ag 2 S and Ag 2 SO 4 were identified as major byproducts of aging, but their impact on iodine adsorption remains unclear. Thus, to further investigate aging, we loaded Ag 2 S and Ag 2 SO 4 powders with molecular iodine (I 2 ) at 150 °C and characterized their properties. The I 2 adsorption capacity of Ag 2 SO 4 was 0.12 wt % after 72 h, suggesting its formation directly reduces the capacity of the Ag 0 -aerogel. Conversely, Ag 2 S had an iodine capacity of 86.8 wt % and near total Ag utilization after 240 h. Given its high capacity and availability, we evaluated the feasibility of Ag 2 S as an I 2 adsorbent in future applications. Finally, several drawbacks need to be overcome, including the relatively slow uptake rate, potential emission of another hazardous byproduct (SO 2 ), and potential aging effects (e.g., Ag 2 S conversion to Ag 2 SO 4 ) before Ag 2 S can be applied for the radioiodine capture process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Redox-Active Crown Ether Copolymer for Selective Lithium Recovery from Spent Lithium-Ion Batteries

The increasing demand for lithium, alongside concerns over resource scarcity and supply chain risks, has driven the need for alternative lithium sources, particularly from spent lithium-ion batteries (LIBs). Here, in this work, we introduce a redox-active crown ether copolymer designed for highly selective and electrochemically reversible lithium recovery from organic LIB leachates. A lithium-selective moiety, (12-crown-4)methyl methacrylate (12C4MA), is combined with a redox-active moiety, ferrocenylpropyl methacrylamide (FPMAm), into a redox copolymer electrosorbent to replace acid-based regeneration with electrostatic repulsion. The redox response enhances lithium ingress into the polymer, doubling lithium uptake (0.58 mol Li /mol CrE ) and enabling electrochemical regeneration upon the FPMAm oxidation. Our system exhibits exclusive lithium uptake, even in complex leachates containing competing metals (e.g., iron, nickel, and cobalt) and organic degradants. Techno-economic analysis highlights high energy efficiency and competitive lithium pricing to the market value (∼$12.7 per kg Li ). Overall, our work demonstrates a scalable, electrified adsorbent platform for sustainable and chemical-free critical metal recovery.

adsorption↗
DOE OSTI2012

Analysis of a Nuclear Accident: Fission and Activation Product Releases from the Fukushima Daiichi Nuclear Facility as Remote Indicators of Source Identification, Extent of Release, and State of Damaged Spent Nuclear Fuel

Measurements of several radionuclides within environmental samples taken from the Fukushima Daiichi nuclear facility and reported on the Tokyo Electric Power Company website following the recent tsunami-initiated catastrophe were evaluated for the purpose of identifying the source term, reconstructing the release mechanisms, and estimating the extent of the release. 136Cs/137Cs and 134Cs/137Cs ratios identified Units 1-3 as the major source of radioactive contamination to the surface soil close to the facility. A trend was observed between the fraction of the total core inventory released for a number of fission product isotopes and their corresponding Gibbs Free Energy of formation for the primary oxide form of the isotope, suggesting that release was dictated primarily by chemical volatility driven by temperature and reduction potential within the primary containment vessels of the vented reactors. The absence of any major fractionation beyond volatilization suggested all coolant had evaporated by the time of venting. High estimates for the fraction of the total inventory released of more volatile species (Te, Cs, I) indicated the damage to fuel bundles was likely extensive, minimizing any potential containment due to physical migration of these species through the fuel matrix and across the cladding wall. 238Pu/239,240Pu ratios close-in and at 30 km from the facility indicated that the damaged reactors were the major contributor of Pu to surface soil at the source but that this contribution likely decreased rapidly with distance from the facility. The fraction of the total Pu inventory released to the environment from venting units 1 and 3 was estimated to be ~0.003% based upon Pu/Cs isotope ratios relative to the within-reactor modeled inventory prior to venting and was consistent with an independent model evaluation that considered chemical volatility based upon measured fission product release trends. Significant volatile radionuclides within the spent fuel at the time of venting but not as yet observed and reported within environmental samples are suggested as potential analytes of concern for future environmental surveys around the site.

Schwantes, Jon M↗
DOE OSTI2021

Development of a numerical model for simulating stress corrosion cracking in spent nuclear fuel canisters

Abstract Prediction and detection of the chloride-induced stress corrosion cracking (CISCC) in Type 304 stainless steel spent nuclear fuel canisters are vital for the lifetime extension of dry storage canisters. This paper conducts a critical review that focuses on the numerical modeling and simulation on the research progress of the CISCC. The numerical models emphasizing the residual stress, susceptible microstructure, and corrosive environment are summarized individually. Meanwhile, the simulation studies on the role of hydrogen-assisted cracking are reviewed. Finally, a multi-physical numerical model, which combines the different fields is proposed based on our recent investigation.

Materials Science↗
DOE OSTI2023

Simultaneous isotopic analysis of fission product Sr, Mo, and Ru in spent nuclear fuel particles by resonance ionization mass spectrometry

Abstract Fission product Sr, Mo, and Ru isotopes in six 10-μm particles of spent fuel from a pressurized water reactor were analyzed by resonance ionization mass spectrometry (RIMS) and evaluated for utility in nuclear material characterization. Previous measurements on these same samples showed widely varying U, Pu, and Am isotopic compositions owing to the samples’ differing irradiation environments within the reactor. This is also seen in Mo and Ru isotopes, which have the added complication of exsolution from the UO 2 fuel matrix. This variability is a hindrance to interpreting data from a collection of particles with incomplete provenance since it is not always possible to assign particles to the same batch of fuel based on isotopic analyses alone. In contrast, the measured 90 Sr/ 88 Sr ratios were indistinguishable across all samples. Strontium isotopic analysis can therefore be used to connect samples with otherwise disparate isotopic compositions, allowing them to be grouped appropriately for interpretation. Strontium isotopic analysis also provides a robust chronometer for determining the time since fuel irradiation. Because of the very high sensitivity of RIMS, only a small fraction of material in each of the 10 μm samples was consumed, leaving the vast majority still available for other analyses.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Discerning the Location and Nature of Coke Deposition from Surface to Bulk of Spent Zeolite Catalysts

The nanoscale compositional mapping of fresh HZSM-5 catalyst synthesized using hydrothermal process as well as after just steaming and after ethanol conversion reaction for 72 hours at realistic catalytic conditions was investigated using atom probe tomography. Atom probe tomography permitted direct atomic scale imaging of non-uniform distribution of Al within the HZSM-5 as well as for the first time image the hydrocarbon coking after ethanol reaction. Clear evidences for existence of multiple C-H molecular species which appear to aggregate as clusters within the pores of spent HZSM-5 catalyst materials is provided. Furthermore, these results provide evidence for the ability of atom probe tomography, a powerful 3D characterization tool in interrogating the atomic scale chemistry of zeolite catalyst materials at industrially relevant catalytic conditions.

54 ENVIRONMENTAL SCIENCES↗