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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Sorbent Regeneration via Radiofrequency-Assisted Dielectric Heating for Direct Air Capture of CO 2

Direct air capture (DAC) of CO 2 is a negative emission technology that utilizes sorbents requiring a regeneration step for repeated ab(/d)sorption–desorption cycles. Here we report an unconventional approach to desorb captured CO 2 from a porous sorbent using radiofrequency (RF) irradiation for dielectric heating and targeted energy transfer, thus enabling modularity and promoting renewable energy input. Regeneration of composites of functional ionic liquid and metal–organic framework with high CO 2 capacity and enhanced transport is demonstrated under conditions relevant to DAC. RF-assisted dielectric heating at the megahertz frequency range shows effective absorption of electromagnetic energy and consequently rapid release of the captured CO 2 .

Ionic liquids↗
DOE OSTI2022

Radioiodine sorbent selection criteria

Methods for preventing radioiodine from entering the environment are needed in processes related to nuclear energy and medical isotope production. The development and performance of many different types of sorbents to capture iodine have been reported on for decades; however, there is yet to be a concise overview on the important parameters that should be considered when selecting a material for chemically capturing radioiodine. This paper summarizes several criteria that should be considered when selecting candidate sorbents for implementation into real-world systems. The list of selection criteria discussed are 1) optimal capture performance, 2) kinetics of adsorption, 3) performance under relevant process conditions, 4) properties of the substrate that supports the getter, and 5) environmental stability and disposition pathways for iodine-loaded materials.

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

Insights into the Oxidative Degradation Mechanism of Solid Amine Sorbents for CO 2 Capture from Air: Roles of Atmospheric Water

Direct air capture (DAC) processes for extraction of CO 2 from ambient air are unique among chemical processes in that they operate outdoors with minimal feed pretreatments. Here, the impact of humidity on the oxidative degradation of a prototypical solid supported amine sorbent, poly(ethylenimine) (PEI) supported on Al 2 O 3 , is explored in detail. By combining CO 2 adsorption measurements, oxidative degradation rates, elemental analyses, solid-state NMR and in situ IR spectroscopic analysis in conjunction with 18 O labeling of water, a comprehensive picture of sorbent oxidation is achieved under accelerated conditions. Here we demonstrated that the presence of water vapor can play an important role in accelerating the degradation reactions. From the study we inferred the identity and kinetics of formation of the major oxidative products, and the role(s) of humidity. Our data are consistent with a radical mediated autooxidative degradation mechanism.

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

Supramolecular Complexation-Enhanced CO 2 Chemisorption in Amine-Derived Sorbents

A supramolecular complexation approach is developed to improve the CO 2 chemisorption performance of solvent-lean amine sorbents. Operando spectroscopy techniques reveal the formation of carbamic acid in the presence of a crown ether. Here, the reaction pathway is confirmed by theoretical simulation, in which the crown ether acts as a proton acceptor and shuttle to drive the formation and stabilization of carbamic acid. Improved CO 2 capacity and diminished energy consumption in sorbent regeneration are achieved.

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

The efficacy and ecological impact of mercury sorbents on the physiology and reproductive fitness of Daphnia magna

Environmental mercury (Hg) contamination threatens ecosystems due to its bioaccumulation and toxicity. Effective and sustainable remediation strategies are essential, with carbon-based sorbents like biochar (BC) and activated carbon (AC) gaining attention for their high adsorption capacity and cost-effectiveness. However, their ecological impacts remain poorly understood. This study evaluates the Hg removal efficacy and ecological effects of three sorbents—BC, granular AC (GAC), and AC fiber (ACF)—in a flow-through column system with and without Hg additions. We tested Hg removal at two concentrations (1 and 4 µg/L Hg) and assessed chronic exposure effects on a sentinel and sensitive freshwater organism, Daphnia magna, over 30 days of exposure to the columns’ effluent. GAC removed 100 % of Hg, while BC and ACF achieved 99 % removal. The ACF + 4 µg/L Hg effluent induced 70 % lethality in D. magna after nearly three weeks of exposure, while the GAC effluent significantly reduced fecundity, even in the absence of Hg exposure. In contrast, the BC effluent enhanced reproductive output, likely due to inputs of carbon and nitrogen in the effluent. These findings highlight the need to balance Hg removal efficacy with ecological safety, emphasizing the importance of considering both remediation effectiveness and potential environmental impacts.

Activated carbon↗
DOE OSTI2022

Silver-Loaded Xerogel Nanostructures for Iodine Capture: A Comparison of Thiolated versus Unthiolated Sorbents

Here this paper describes the development and provides comparisons of thiolated (-SH) and unthiolated Ag-Al-Si-O xerogels for iodine gas capture. These xerogels were produced from alkoxides and then heat-treated at 350 °C to provide mechanical strength for subsequent processing steps. Then, a portion of the xerogels was thiolated using (3-mercaptopropyl)trimethoxysilane. Next, thiolated and unthiolated batches were ion-exchanged in AgNO 3 solutions where Ag + replaced Na + in the gel network on a near 1:1 molar basis. Subsamples of the Ag-exchanged xerogels were subjected to a reduction step in H 2 /Ar to convert Ag + to Ag 0 where the rest of the Ag-exchanged (Ag + ) were not reduced. X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed nanoscale Ag 0 in the Ag + samples despite no active reduction where actively reduced samples had bimodal Ag 0 distribution of ~2-3 nm hexagonal and ~6-7 nm cubic crystallites. Synchrotron X-ray absorption spectroscopy was used to assess the oxidization states of Ag, S, and I within the different xerogel samples. The specific surface areas of the base xerogels decreased as subsequent treatments were performed on the as-made samples, albeit the decreases were smaller than aerogel equivalents of these samples from a previous study. All iodine-loaded Ag-based samples showed a mixture of β-AgI and γ-AgI. Comparisons of iodine-loading results with other Ag-based iodine sorbents show that the thiolated Ag 0 -xerogels in this work have one of the highest iodine-loading capacities (q e ) reported to date in saturated conditions with the thiolated Ag 0 -xerogel showing 522 mg iodine per g of the sorbent.

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

Feasibility of carbon foam-based sorbents for the abatement of gaseous mercury and iodine

The U.S. Department of Energy Hanford Site in Washington State is in the process of commissioning the Waste Treatment and Immobilization Plant to process a portion of the 54 million gallons of radioactive and chemical waste from cold war weapon production. Technologies for the capture of volatile species of concern are still being assessed, and new methods and materials are developed as operational and flowsheet mission risks are identified. One such area still being assessed is the abatement efficacy of the Carbon Adsorber units to retain gaseous mercury and 129 I released during processing. It is challenging to predict the mercury chemistry due to the variability of the feed, and different methods/materials are required for the capture of gaseous Hg 0 and Hg II compounds. In this study, the feasibility of using developmental carbon foam (CF) sorbents for the capture of iodine and mercury was assessed using static and dynamic flow testing and compared against a commercially available sorbent, BATII-37. Both CF and CF functionalized with bismuth particles (CF-Bi) chemisorbed iodine, and CF-Bi had similar mercury capture performance to BATII-37 in dynamic flow tests. While species loading concentrations were measurable, limitations in achieving a mass balance prevented a full evaluation of capture efficacy. Nonetheless, the results serve as an important first step in demonstrating the potential for simultaneous iodine and mercury capture.

Hanford site↗
DOE OSTI2022

Demo-scale testing of a hybrid membrane-sorbent system for post-combustion CO2 capture

TDA Research is developing a novel hybrid membrane-sorbent system for the post-combustion capture of carbon dioxide (CO 2 ) from supercritical pulverized coal (PC) power generation facilities or large point industrial emitters. Here, the novel design incorporates a 1st-stage continuous membrane separator developed by Membrane Technology and Research, Inc. (MTR) with a dual-bed radial-flow sorbent contactor (designed and developed at TDA). Testing of a pilot unit at 1 MWe scale has been conducted at the site for emerging technologies at the Technology Centre Mongstad (TCM) in Mongstad, Norway using residue fluid catalytic cracker (RFCC) flue gas from Equinor’s Mongstad refinery.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Transformational Sorbent-Based Process for a Substantial Reduction in the Cost of CO2 Capture

Adsorption processes have the potential to significantly reduce the CO2 capture cost from power plants and industrial flue gases. InnoSepra has developed several sorbent-based technologies to obtain very high CO2 recovery and high purity CO2 while meeting the EOR/sequestration product specifications. A first-generation process was shown to achieve CO2 recoveries greater than 94% at CO2 purities in the range of 98.5-99.5%. The absolute heat energy required for the process was not only 40% lower than MEA but also was needed at a much lower temperature. This work will present the performance of the second-generation InnoSepra process which is based on a breakthrough sorbent regeneration method. This process has a projected 45% lower capital cost compared to MEA, less than 16% loss in plant output for CO2 capture and compression, and a CO2 capture cost at least 55% lower than MEA. Lab scale testing and the process simulations indicate a CO2 capture performance similar to or better than the first-generation process. Pilot scale drying and breakthrough tests were carried out at the Technology Centre Mongstad (TCM), Norway, and lab-scale cyclic tests were carried out at InnoSepra to confirm the process improvement. During these tests, InnoSepra’s flue gas purification technology was also tested at TCM. It can provide a low-cost option for the removal of NO2 and SOX to sub-ppm levels as well as a significant reduction in aerosol emissions.

08 HYDROGEN↗
DOE OSTI2026

Transformational Molecular Layer Deposition Tailor-Made Size-Sieving Sorbents for Post-Combustion CO 2 Capture

This report summarizes the carbon capture research and development conducted by The State University of New York at Buffalo (UB), University of South Carolina (USC), GTI Energy (GTI), and Rensselaer Polytechnic Institute (RPI) for U.S. Department of Energy (DOE) project DE-FE0031730 titled “Transformational Molecular Layer Deposition Tailor-made Size-Sieving Sorbents for Post-Combustion CO 2 capture.” The objective of this project was to develop a transformational molecular layer deposition (MLD) tailor-made size-sieving sorbent integrated with a pressure swing adsorption (PSA) cycle schedule that can be installed in new or retrofitted into existing pulverized coal (PC) power plants for CO 2 capture with a cost of electricity at least 30% lower than a supercritical PC power with CO 2 capture, or approximately $\$$30 per tonne of CO 2 captured, and with it being ready for demonstration by 2030.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2024

Concentration of Kr from Simulated Dissolver Off-Gas Streams Utilizing a Solid Sorbent, HZ-PAN

Idaho National Laboratory (INL) has developed and tested engineered sorbents to separate and capture volatile fission products such iodine, xenon (Xe), and krypton (Kr) from off-gas streams. A study was conducted using a solid sorbent, HZ-PAN, to concentrate Kr from a simulated dissolver off-gas stream. The study demonstrates that four adsorption-desorption cycles can transform a 150 ppmv Kr stream into a 37.5% Kr stream, an overall concentration factor of 2497.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

ASC Poster - Concentration of Xe from Simulated Dissolver Off-gas Streams Utilizing a Solid Sorbent, AgZ-PAN

Idaho National Laboratory (INL) has developed and tested engineered sorbents to separate and capture volatile fission products such iodine (I), xenon (Xe), and krypton (Kr) from off-gas streams. As noble gases, Xe and Kr can be difficult to capture and separate. Historically, cryogenic distillation has been used to execute the separation, but this method can pose significant hazards. INL has successfully developed two sorbents for Xe and Kr capture, silver mordenite polyacrylonitrile (AgZ-PAN) and hydrogen mordenite polyacrylonitrile (HZ-PAN). Adsorption studies to date successfully separated and captured Xe from carrier gas streams, but those studies focused primarily on initial separation and capture. In addition, the ability to concentrate Xe through multiple adsorption and desorption cycles has not been studied and therefore is the focus on this presentation. Concentrating Xe during desorption is ideal to produce Xe that can be used for commercial and research applications.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Precision Calcination Mechanism of CaCO 3 to High-Porosity Nanoscale CaO CO 2 Sorbent Revealed by Direct In Situ Observations

Deploying energy storage and carbon capture at scale is hindered by the substantial endothermic penalty of decomposing CaCO 3 to CaO and CO 2 , and the rapid loss of CO 2 absorption capacity by CaO sorbent particles due to sintering at the high requisite decomposition temperatures. The decomposition reaction mechanism underlying sorbent deactivation remains unclear at the atomic level and nanoscale due to past reliance on postmortem characterization methods with insufficient spatial and temporal resolution. Thus, elucidating the important CaCO 3 decomposition reaction pathway requires direct observation by time-resolved (sub-)nanoscale methods. Here, chemical and structural dynamics during the decomposition of CaCO 3 nanoparticles to nanoporous CaO particles comprising high-surface-area CaO nanocrystallites are examined. Comparing in situ transmission electron microscopy (TEM) and synchrotron X-ray diffraction experiments gives key insights into the dynamics of nanoparticle calcination, involving anisotropic CaCO 3 thermal distortion before conversion to thermally dilated energetically stable CaO crystallites. Time-resolved TEM uncovered a novel CaO formation mechanism involving heterogeneous nucleation at extended CaCO 3 defects followed by sweeping reaction front motion across the initial CaCO 3 particle. These observations clarify longstanding, yet incomplete, reaction mechanisms and kinetic models lacking accurate information about (sub-)nanoscale dynamics, while also demonstrating calcination of CaCO 3 without sintering through rapid heating and precise temperature control.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Magnetic nanoparticle‐induced sorbent regeneration for direct air capture

Direct air capture (DAC) is a promising technology for decarbonization through the removal of CO 2 from the atmosphere. In many DAC processes, the regeneration energy used to restore the capture capacity of sorbents accounts for a significant fraction of the energy required by the whole process. Here we report an effective and scalable sorbent regeneration method for liquid DAC solvents based on magnetic nanoparticles (MNPs) heating with AC magnetic fields. MNPs can be directly heated to provide uniform and rapid volumetric heating, as we demonstrate by promoting the release of captured CO 2 from an aqueous solution of potassium sarcosinate. Our results showed that 90% of the solvent can be regenerated within 7.5 min of heating through proposed technique. The MNPs and solvent are found to be stable during the regeneration process and the MNPs showed long-term stability in the CO 2 -saturated solvent. Cyclic experiments showed that the nanoparticles can be reused for multiple cycles without performance deterioration. The process is operated in a noncontact mode through electromagnetic waves, making it an adoptable approach for existing carbon capture systems. The MNPs heating provides an effective regeneration strategy for liquid solvents used in carbon capture processes, in particular for DAC.

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

Computational Identification and Experimental Demonstration of High‐Performance Methane Sorbents

Abstract Remarkable methane uptake is demonstrated experimentally in three metal‐organic frameworks (MOFs) identified by computational screening: UTSA‐76, UMCM‐152 and DUT‐23‐Cu. These MOFs outperform the benchmark sorbent, HKUST‐1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high‐affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

Nath, Karabi↗
DOE OSTI2023

Insights into the Oxidative Degradation Mechanism of Solid Amine Sorbents for CO 2 Capture from Air: Roles of Atmospheric Water

Abstract Direct air capture (DAC) processes for extraction of CO 2 from ambient air are unique among chemical processes in that they operate outdoors with minimal feed pretreatments. Here, the impact of humidity on the oxidative degradation of a prototypical solid supported amine sorbent, poly(ethylenimine) (PEI) supported on Al 2 O 3 , is explored in detail. By combining CO 2 adsorption measurements, oxidative degradation rates, elemental analyses, solid‐state NMR and in situ IR spectroscopic analysis in conjunction with 18 O labeling of water, a comprehensive picture of sorbent oxidation is achieved under accelerated conditions. We demonstrated that the presence of water vapor can play an important role in accelerating the degradation reactions. From the study we inferred the identity and kinetics of formation of the major oxidative products, and the role(s) of humidity. Our data are consistent with a radical mediated autooxidative degradation mechanism.

Carneiro, Juliana S. A.↗
DOE OSTI2022

Computational Identification and Experimental Demonstration of High‐Performance Methane Sorbents

Abstract Remarkable methane uptake is demonstrated experimentally in three metal‐organic frameworks (MOFs) identified by computational screening: UTSA‐76, UMCM‐152 and DUT‐23‐Cu. These MOFs outperform the benchmark sorbent, HKUST‐1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high‐affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

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

CO 2 Chemisorption Behavior of Coordination-Derived Phenolate Sorbents

CO 2 chemisorption via C-O bond formation is an efficient methodology in carbon capture especially using phenolate-based ionic liquids (ILs) as the sorbents to afford carbonate products. However, most of the current IL systems involve alkylphosphonium cations, leading to side reactions via the ylide intermediate pathway. It is important to figure out the CO 2 chemisorption behavior of phenolate-derived sorbents using inactive and easily accessible cation counterparts without active protons. Herein, phenolate-based systems were constructed via coordination between alkali metal cations with crown ethers to avoid the participation of active protons in CO 2 chemisorption. Reaction pathway study revealed that CO 2 uptake could be achieved by O-C bond formation to afford carbonate. CO 2 uptake capacity and reaction enthalpy were significantly influenced by the coordination effect, alkali metal types, and alkyl groups on the benzene ring.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗