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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Glucose Conversion to Furans in Alcohols Catalyzed by Lewis Acidic Beta Zeolites and Brønsted Acidic Resins

Glucose was converted to 5-(hydroxymethyl)furfural (HMF) and the potential biodiesel additives 5-(ethoxymethyl)furfural (EMF) and 5-(isopropoxymethyl)furfural (IMF) by Lewis acidic zeolites and Brønsted acidic resins. The conversion occured by sequential isomerization and dehydration reactions in semiaqueous mixtures containing ethanol or isopropanol. Sn-beta and Amberlyst® 15 catalyzed the conversion of glucose to HMF and IMF in 53% yield in isopropanol containing 7.5 weight % water. The yield of undetected byproducts including humins was 7%. The moderate yield is attributed to the increased selectivity of the isomerization reaction and the suppression of further reactions of HMF to byproducts such as levullinic acid, formic acid, and humins in the alcohols.

09 BIOMASS FUELS↗
DOE OSTI2022

Gas diffusion electrodes, reactor designs and key metrics of low-temperature CO 2 electrolysers

We report that CO 2 emissions can be recycled via low-temperature CO 2 electrolysis to generate products such as carbon monoxide, ethanol, ethylene, acetic acid, formic acid and propanol. In recent years, progress has been made towards an industrially relevant performance by leveraging the development of gas diffusion electrodes (GDEs), which enhance the mass transport of reactant gases (for example, CO 2 ) to the active electrocatalyst. Innovations in GDE design have thus set new benchmarks for CO 2 conversion activity. In this Review, we discuss GDE-based CO 2 electrolysers, in terms of reactor designs, GDE composition and failure modes, to identify the key advances and remaining shortfalls of the technology. This is combined with an overview of the partial current densities, efficiencies and stabilities currently achieved and an outlook on how phenomena such as carbonate formation could influence the future direction of the field. Our aim is to capture insights that can accelerate the development of industrially relevant CO 2 electrolysers.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

The Reaction of Criegee Intermediate CH 2 OO with Water Dimer: Primary Products and Atmospheric Impact

The rapid reaction of the smallest Criegee intermediate, CH 2 OO, with water dimers is the dominant removal mechanism for CH 2 OO in the Earth's atmosphere, but its products are not well understood. This reaction was recently suggested as a significant source of the most abundant tropospheric organic acid, formic acid (HCOOH), which is consistently underpredicted by atmospheric models. Furthermore, using time-resolved measurements of reaction kinetics by UV absorption and product analysis by photoionization mass spectrometry, we show that the primary products of this reaction are formaldehyde and hydroxymethyl hydroperoxide (HMHP), with direct HCOOH yields of less than 10%. Incorporating our results into a global chemistry-transport model further reduces HCOOH levels by 10–90%, relative to previous modeling assumptions, which indicates that the reaction CH 2 OO + water dimer by itself cannot resolve the discrepancy between the measured and predicted HCOOH levels.

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

Characterizing sources and emissions of volatile organic compounds in a northern California residence using space- and time-resolved measurements

We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single-family house in California utilizing time- and space-resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8 weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time-resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short-term enhancements (spikes) well above the indoor baseline. Compounds were categorized as "high-baseline" or "spike-dominated" based on indoor-to-outdoor concentration ratio and indoor mean-to-median ratio. Short-term spikes were associated with occupants and their activities, especially cooking. High-baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high-baseline species, quantified with 2-hour resolution, exhibited strong temperature dependence and were affected by air-change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high-baseline species.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Corrosion of Ferrous Alloys by Organic Compounds in Simulated Bio-Oils

Bio-oils derived from biomass contain organic species and acids that can be corrosive to steel-based structural materials used for pipelines and storage tanks. It is, therefore, important to assess corrosivity of organic constituents in bio-oils and identify ferrous alloys with sufficient corrosion resistance. In this work, lactobionic acid, formic acid and catechol were selected for corrosive constituents in bio-oils and used to formulate simulated bio-oils where 4 ferrous alloys, including 2.25Cr-1Mo steel and type 410, 201 and 316 stainless steels, were tested by Electrochemical Impedance Spectroscopy (EIS). The corrosivity of each simulated bio-oils was assessed using R2, a charge transfer limiting resistance fitted from EIS spectra. Whie 2.25Cr-1Mo steel exhibited active corrosion with low R2 values, the stainless steels showed high R2 values associated with passive state. The values of R2, considered proportional to the stability of the passive film, appeared lower in lactobionic acid than the other simulated bio-oils for the stainless steels, suggesting that lactobionic acid could be more aggressive to passive film than the other constituents of bio-oils. The overall goal of this work is to use EIS to systematically study the impact of bio-oil constituents on corrosion of candidate structural materials for bio-oil production, transport, and storage, as well as provide feedback for potential optimization of bio-oil chemistries to reduce the risk of corrosion.

Jun, Jiheon↗
DOE OSTI2020

Flowthrough Pretreatment of Softwood under Water-only and Alkali Conditions

Flowthrough pretreatment provides valuable insight in the fundamentals of deconstruction of plant biomass. In this study, the potential softwood degradation pathways under water-only and alkali conditions were determined by elucidating the deconstructed biomass-derived products at 0-270 °C for 2-10 min at a flow rate of 25 mL/min with water-only or alkaline at initial pH of 8, 9, 11, and 12, respectively. Results indicated that the initial pH value was a convenient indicator along with the severity parameter to control biomass degradation through the non-oxidative (pH<9) and oxidative (pH=9) pathways. Up to 100 % of hemi-sugars, 90 % of cellulose, and 70 % of lignin were derived from softwood under non-oxidative conditions at severity parameter LogR0 around 5.5, respectively. On the contrary, at pH 12, the oxidative degradation resulted in pretreated hydrolysate rich in monomeric and oligomeric phenolic products as well as glycolic acid, acetic acid, and formic acid from carbohydrates. The two dimensional 1H-13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) analysis revealed that non-oxidative degradation at initial pH values lower than 9 mainly cleaved ß-O-4, all of the ß-ß, and ß-5/a-O-4 linkages, whereas substantial aromatic ring structures with limited ß-O-4 structures remaining at pH 12 through oxidative degradation.

Zhang, Libing↗
DOE OSTI2012

An in Situ NMR Study of the Mechanism for the Catalytic Conversion of Fructose to 5-Hydroxymethylfurfural and then to Levulinic Acid Using 13 C Labeled d -Fructose

The pathways for the formation of 5-hydroxymethylfurfural (HMF) by dehydration of d-fructose and for the formation of levulinic acid and formic acid from HMF by rehydration were investigated by in situ13C and 1H NMR using both unlabeled and 13C-labeled fructose. Water or DMSO was used as the solvent with Amberlyst 70, PO43–/niobic acid, or sulfuric acid as catalysts. Only HMF is observed using NMR for fructose dehydration in DMSO with any of the three catalysts or without a catalyst. For each system, results with 13C-labeled fructose indicate that the first carbon (C-1) or sixth carbon (C-6) of fructose maps onto the corresponding carbons of HMF. For fructose dehydration in H2O with a PO43–/niobic acid catalyst, in addition to HMF, furfural was observed as a product. However, we show that furfural is not a reaction product deriving from HMF under our conditions. Rather our data indicate that there is a parallel reaction pathway open to fructose when the reaction takes place in H2O with a PO43–/niobic acid catalyst. The corresponding 13C-labeled results show that the first carbon in fructose maps onto the first carbon (aldehyde carbon) in furfural. Using 13C-enriched HMF formed from dehydration of 13C-labeled fructose in DMSO or H2O, we investigated the pathway for HMF rehydration to levulinic and formic acid. The data in different solvents and with different catalysts are consistent with a common mechanism for HMF rehydration, which results in the C-1 and C-6 carbon of HMF being transformed to the carbon of formic acid and methyl carbon (C-5) of levulinic acid, respectively.

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

Low-Temperature Electrochemical Upgrading of Bio-oils Using Polymer Electrolyte Membranes

While bio-oil-derived fuels hold much promise as a replacement for petroleum, transformation of the highly oxygenated mixture has proven challenging. In particular, bio-oils are reactive and difficult to upgrade through catalytic pyrolysis. To reach a stabilized product capable of deep deoxygenation at elevated pressure and temperature, conversion or separation of reactive groups is required. This paper describes an electrochemical process for stabilization and upgrading of bio-oils prior to hydrotreating at high pressure and temperature. This electrolytic process uses a three-compartment cell designed to hydrogenate reactive carbonyl components while separating small acid molecules, such as acetic and formic acids, which act as catalysts for condensation reactions and consume hydrogen gas to produce low-value gases in hydrotreating. To avoid conductivity issues, electrodes are appended to anion- and cation-exchange membranes. The cell was tested using a mixed acetic acid and formic acid surrogate fed to the cathode compartment, where the decrease in the concentration followed the applied charge to the cell. Experiments performed using pine pyrolysis oil demonstrated a significant reduction in the total acid number (TAN), an increase in pH from 2.6 to over 4, and a modest reduction of the carbonyl concentration. Analysis showed the reduction in TAN was primarily due to removal of carboxylic compounds. Experiments observed a decrease in the reactive carbonyl (aldehydes and ketones) concentration that followed applied charge. The results with the newly devised reactor show promise for the electrochemical route for upgrading bio-oils, but significant improvements in TAN removal and carbonyl conversion are needed. Given the distributed nature of biomass, an electrochemical process paired with pyrolysis could be used to densify and stabilize an oil product near the source. The densified liquid could then be shipped to centralized refineries for final upgrading to fuel and/or chemical products.

Lister, Tedd↗
DOE OSTI2016

Impact of scaling on the nitric-glycolic acid flowsheet

Savannah River Remediation (SRR) is considering using glycolic acid as a replacement for formic acid in Sludge Receipt and Adjustment Tank (SRAT) processing in the Defense Waste Processing Facility (DWPF). Catalytic decomposition of formic acid is responsible for the generation of hydrogen, a potentially flammable gas, during processing. To prevent the formation of a flammable mixture in the offgas, an air purge is used to dilute the hydrogen concentration below the 60% of the Composite Lower Flammability Limit (CLFL). The offgas is continuously monitored for hydrogen using Gas Chromatographs (GCs). Since formic acid is much more volatile and toxic than glycolic acid, a formic acid spill would lead to the release of much larger quantities to the environment. Switching from formic acid to glycolic acid is expected to eliminate the hydrogen flammability hazard leading to lower air purges, thus downgrading of Safety Significant GCs to Process Support GCs, and minimizing the consequence of a glycolic acid tank leak in DWPF. Overall this leads to a reduction in process operation costs and an increase in safety margin. Experiments were completed at three different scales to demonstrate that the nitric-glycolic acid flowsheet scales from the 4-L lab scale to the 22-L bench scale and 220-L engineering scale. Ten process demonstrations of the sludge-only flowsheet for SRAT and Slurry Mix Evaporator (SME) cycles were performed using Sludge Batch 8 (SB8)-Tank 40 simulant. No Actinide Removal Process (ARP) product or strip effluent was added during the runs. Six experiments were completed at the 4-L scale, two experiments were completed at the 22-L scale, and two experiments were completed at the 220-L scale. Experiments completed at the 4-L scale (100 and 110% acid stoichiometry) were repeated at the 22-L and 220-L scale for scale comparisons.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2002

A Sensitive VLA Search for Small-Scale Glycine Emission Toward OMC-1

We have conducted a deep Q-band (lambda-7 mm) search with the Very Large Array (VLA) toward OMC-1 for the lowest energy conformation (conformer I) of glycine (NH2CH2COOH) in four rotational transitions: the 6(sub 15)- 5(sub 14), 6(sub 24)-5(sub 23), 7(sub 17- 6(sub 16), and 7(sub 07)-6(sub 06). Our VLA observations sample the smallest-scale structures to date in the search for glycine toward OMC-1. No glycine emission features were detected. Thus if glycine exists in OMC-1, either it is below our detection limit, or it is more spatially extended than other large molecules in this source, or it is primarily in its high energy form (conformer II). Our VLA glycine fractional abundance limits in OMC-1 are comparable to those determined from previous IRAM 30m measurements -- somewhat better or worse depending on the specific source model -- and the entire approximately 1 foot primary beam of the VLA was searched while sensitive to an areal spatial scale approximately 150 times smaller than the 24 inch beam of the IRAM single-element telescope. In the course of this work, we detected and imaged the 4(sub 14)-3(sub 13) A and E transitions of methyl formate (HCOOCH3) and also the 2(sub 02) - 1(sub 01) transition of formic acid (HCOOH). Since formic acid is a possible precursor to glycine, our glycine limits and formic acid results provide a constraint on this potential formation chemistry route for glycine in OMC-1.

Hollis, J. M.↗
DOE OSTI2016

1,2-Addition of Formic or Oxalic Acid to – N{CH 2 CH 2 (PiPr 2 )} 2 -Supported Mn(I) Dicarbonyl Complexes and the Manganese-Mediated Decomposition of Formic Acid

(PN H P)Mn(CO) 2 (I) carboxylate complexes (PN H P = HN{CH 2 CH 2 (PiPr 2 )} 2 ) were prepared in this study via 1,2-addition of either formic or oxalic acid to (PNP)Mn(CO) 2 (PNP = the deprotonated, amide form of the ligand –N{CH 2 CH 2 (PiPr 2 )} 2 ). The structural and spectral properties of these complexes were compared. The manganese formate complex was found to be dimeric in the solid state and monomeric in solution. Half an equivalent of oxalic acid was employed to form the bridging oxalate dimanganese complex. The catalytic competencies of the carboxylate complexes were assessed, and the formate complex was found to decompose formic acid catalytically. Both dehydrogenation and dehydration pathways were active as assessed by the presence of H 2 , CO 2 , and H 2 O. Lastly, the addition of LiBF 4 exhibited a strong inhibitory effect on the catalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

DWPF COAL-CARBON WASTE ACCEPTANCE CRITERIA LIMIT EVALUATION BASED ON EXPERIMENTAL WORK (TANK 48 IMPACT STUDY)

This report summarizes the results of both experimental and modeling studies performed using Sludge Batch 10 (SB10) simulants and FBSR product from Tank 48 simulant testing in order to develop higher levels of coal-carbon that can be managed by DWPF. Once the Fluidized Bed Steam Reforming (FBSR) process starts up for treatment of Tank 48 legacy waste, the FBSR product stream will contribute higher levels of coal-carbon in the sludge batch for processing at DWPF. Coal-carbon is added into the FBSR process as a reductant and some of it will be present in the FBSR product as unreacted coal. The FBSR product will be slurried in water, transferred to Tank Farm and will be combined with sludge and washed to produce the sludge batch that DWPF will process. The FBSR product is high in both water soluble sodium carbonate and unreacted coal-carbon. Most of the sodium carbonate is removed during washing but all of the coal-carbon will remain and become part of the DWPF sludge batch. A paper study was performed earlier to assess the impact of FBSR coal-carbon on the DWPF Chemical Processing Cell (CPC) operation and melter off-gas flammability by combining it with SB10-SB13. The results of the paper study are documented in Ref. 7 and the key findings included that SB10 would be the most difficult batch to process with the FBSR coal present and up to 5,000 mg/kg of coal-carbon could be fed to the melter without exceeding the off-gas flammability safety basis limits. In the present study, a bench-scale demonstration of the DWPF CPC processing was performed using SB10 simulants spiked with varying amounts of coal, and the resulting seven CPC products were fed to the DWPF melter cold cap and off-gas dynamics models to determine the maximum coal that can be processed through the melter without exceeding the off-gas flammability safety basis limits. Based on the results of these experimental and modeling studies, the presence of coal-carbon in the sludge feed to DWPF is found to have both positive (+) and negative (-) impact as summarized below: (-) Coal-carbon is a melter reductant. If excess coal-carbon is present, the resulting melter feed may be too reducing, potentially shortening the melter life. During this study, the Reduction/Oxidation Potential (REDOX) of the melter could be controlled by varying the ratio of nitric and formic acid. (-) The addition of coal-carbon increases the amount of nitric acid added and decreases the amount of formic acid added to control melter REDOX. This means that the CPC with the FBSR product is much more oxidizing than current CPC processing. In this study, adequate formic acid was present in all experiments to reduce mercury and manganese, two of the main goals of CPC processing. (-) Coal-carbon will be oxidized to carbon dioxide or carbon monoxide in the melter. The addition of coal-carbon to the FBSR product will lead to approximately 55% higher offgas production from formate, nitrate and carbon due to the decomposition of the carbon at the maximum levels in this testing. Higher offgas production could lead to higher cold cap coverage or melter foaming which could decrease melt rate. No testing was performed to evaluate the impact of the higher melter offgas flow. (+) The hydrogen production is greatly reduced in testing with coal as less formic acid is added in CPC processing. In the high acid run without coal, the peak hydrogen generation was 15 times higher than in the high acid run with added coal-carbon. (+) Coal-carbon is a less problematic reducing agent than formic acid, since the content of both carbon and hydrogen are important in evaluating the flammability of the melter offgas. Processing with coal-carbon decreases the amount of formic acid added in the CPC, leading to a lower flammability risk in processing with coal-carbon compared to the current DWPF flowsheet. (+) The seven SB10 formulations which were tested during the bench-scale CPC demonstration were all determined to be within the off-gas flammability safety basis limits during the 9X/5X off-gas surge for normal bubbled melter operation. The concentration of coal-carbon in these baseline melter feeds varied widely from 0 to 17,863 ppm, depending on the acid addition strategy used and the extent to which the required reductant (formic acid) was replaced with coal-carbon. All baseline feeds were redox-adjusted and three of them contained TOC higher than the current theoretical TSR limit of 18,900 ppm. (-) Additional coal-carbon was then added to each baseline feed until the calculated off-gas flammability equaled the safety basis limit of 60% of the LFL at the peak of off-gas surge ('max-coal'). In doing so, however, no counterbalancing nitrate was added, thus simulating the scenario where slugs of coal enter the melter as a result of uneven distribution of coal in the slurry.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2011

Electron collisions with hydrogen-bonded complexes

We investigated elastic collisions of low-energy electrons with the hydrogen-bonded formic-acid dimer, formamide dimer, and formic-acid-formamide complex. We focused on how the {pi}{sup *} shape resonances of the isolated monomers are affected when bonded to another molecule. The scattering cross sections were computed with the Schwinger multichannel method with pseudopotentials in the static-exchange and static-exchange-plus-polarization approximations, for energies ranging from 1 to 6 eV. The present results support the existence of two low-lying {pi}{sup *} shape resonances for the formic-acid dimer, as suggested in previous theoretical and experimental studies. We also found low-lying {pi}{sup *} shape resonances for the formamide dimer and for the formic-acid-formamide complex. For the dimers, the presence of a center of inversion is key to understanding how these resonances arise from linear combinations of the {pi}{sup *} anion states of the respective monomers. For the formic-acid-formamide complex, the resonances are more localized on each unit, lying at lower energies with respect to the isolated monomers. The present results suggest that if there is no delocalization of the {pi}{sup *} resonances over the pair for hydrogen-bonded molecules, then their positions would lie below those of the units.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Can Isoprene Oxidation Explain High Concentrations of Atmospheric Formic and Acetic Acid over Forests?

Formic and acetic acid concentrations are particularly high over forested areas of the world. However, the gas-phase mechanisms for producing these acids are poorly understood even for isoprene, the globally dominant biogenic hydrocarbon. We quantified formic and acetic acid production from reactions of hydroxyl radical (OH) (between high and low ranges of nitric oxide (NO) levels) with isoprene, methacrolein (MACR), isoprene epoxydiol (IEPOX), isoprene hydroxy hydroperoxide (ISOPOOH), and α-pinene from the focused isoprene experiments at California Institute of Technology (FIXCIT) laboratory chamber study. We find that (i) OH oxidation of MACR, IEPOX, and ISOPOOH are sources of formic acid, (ii) isoprene peroxy radical isomerization and associated photolysis oxidation products are potentially important sources of organic acids, and (iii) high levels of NO generally suppress organic acid formation from OH oxidation of isoprene. We modified existing chemical mechanisms for isoprene oxidation to account for organic acid production pathways observed in the FIXCIT study. We simulated organic acid production during the Southeastern Oxidant and Aerosol Study using the updated chemical mechanisms and represented acetic acid within a factor of 2 but still underpredicted formic acid by a factor of 6. While we cannot explain ambient formic acid with explicit chemical mechanisms, the FIXCIT results suggest that the oxidation of isoprene could account for as much as 70% of the global annual production of formic acid from gas-phase reactions.

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

Evaluation Of Chemical Additives For Glycolate Destruction In The Recycle Collection Tank

Savannah River National Laboratory (SRNL) has completed a work scope in support of the Savannah River Remediation (SRR) Nitric-Glycolic flowsheet. Glycolic acid will replace formic acid as a reducing agent in the pre-processing of High-Level Waste sludge performed at the Defense Waste Processing Facility (DWPF). Glycolic acid will perform the same function as formic acid, namely reduction of mercury and adjustment of feed rheology and melter oxidation/reduction potential, while significantly reducing the potential for hydrogen generation in DWPF processing. Development testing has demonstrated glycolic acid virtually eliminates hydrogen production in the pre-processing steps. The Nitric-Glycolic flowsheet significantly improves DWPF’s ability to address Savannah River Site’s key challenge - the incorporation of effluent received from the Salt Waste Processing Facility (SWPF). SWPF will deliver significant effluent volume to DWPF, resulting in a concurrent increase in DWPF effluent returned to the Concentration, Storage and Transfer Facilities (CSTF). This work scope demonstrates that glycolate can be destroyed under the Nitric-Glycolic flowsheet prior to returning the DWPF recycle stream to CSTF. To avoid potential flammability issues due to thermolysis of glycolate in CSTF, SRR tasked SRNL to quantify and mitigate glycolate returns via DWPF recycle stream. The development of a strategy for glycolic mitigation initiated with a system’s engineering workshop. Various chemical and/or physical solutions for how to and where to destroy glycolate were considered – consistent with DWPF operational capabilities and process requirements. The workshop identified chemical oxidation of glycolate within the DWPF Recycle Collection Tank (RCT)a as the most promising option with sodium permanganate and Fenton’s reagent (metallic ion catalyzed hydrogen peroxide) as the two most promising oxidants.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Evaluation of chemical additives for glycolic destruction in the recycle collection tank

Savannah River National Laboratory (SRNL) has completed a work scope in support of the Savannah River Remediation (SRR) Nitric-Glycolic flowsheet. Glycolic acid will replace formic acid as a reducing agent in the pre-processing of High-Level Waste sludge performed at the Defense Waste Processing Facility (DWPF). Glycolic acid will perform the same function as formic acid, namely reduction of mercury and adjustment of feed rheology and melter oxidation/reduction potential, while significantly reducing the potential for hydrogen generation in DWPF processing. Development testing has demonstrated glycolic acid virtually eliminates hydrogen production in the pre-processing steps. The Nitric-Glycolic flowsheet significantly improves DWPF’s ability to address Savannah River Site’s key challenge - the incorporation of effluent received from the Salt Waste Processing Facility (SWPF). SWPF will deliver significant effluent volume to DWPF, resulting in a concurrent increase in DWPF effluent returned to the Concentration, Storage and Transfer Facilities (CSTF). This work scope demonstrates that glycolate can be destroyed under the Nitric-Glycolic flowsheet prior to returning the DWPF recycle stream to CSTF. To avoid potential flammability issues due to thermolysis of glycolate in CSTF, SRR tasked SRNL to quantify and mitigate glycolate returns via DWPF’s recycle stream. The development of a strategy for glycolic mitigation was initiated with a system’s engineering workshop. Various chemical and/or physical solutions for how and where to destroy glycolate were considered – consistent with DWPF’s operational capabilities and process requirements. The workshop identified chemical oxidation of glycolate within the DWPF Recycle Collection Tank (RCT) a as the most promising option with sodium permanganate and Fenton’s reagent (metallic ion catalyzed hydrogen peroxide) as the two most promising oxidants.

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

Permanganate Oxidation of Defense Waste Processing Facility (DWPF) Recycle Collection Tank (RCT) Simulants – Protocol Runs for Nominal and Chemical Process Cell (CPC) Foamover Conditions

Savannah River National Laboratory (SRNL) has completed a work scope in support of the Savannah River Remediation (SRR) Nitric-Glycolic flowsheet. Glycolic acid will replace formic acid as a reducing agent in the pre-processing of High-Level Waste sludge performed at the Defense Waste Processing Facility (DWPF). Glycolic acid will perform the same function as formic acid, namely reduction of mercury and adjustment of feed rheology and melter oxidation/reduction potential, while significantly reducing the potential for hydrogen generation in DWPF processing. Development testing has demonstrated glycolic acid virtually eliminates hydrogen production in the pre-processing steps. The Nitric-Glycolic flowsheet significantly improves DWPF’s ability to address one of the Savannah River Site’s key challenges - the incorporation of effluent received from the Salt Waste Processing Facility (SWPF). SWPF will deliver significant effluent volume to DWPF, resulting in a concurrent increase in DWPF effluent returned to the Concentration, Storage and Transfer Facilities (CSTF). This work scope demonstrates that glycolate can be destroyed under the Nitric-Glycolic flowsheet prior to returning the DWPF recycle stream to CSTF. To avoid potential flammability issues due to thermolysis of glycolate in CSTF, SRR tasked SRNL to quantify and mitigate glycolate returns via DWPF’s recycle stream. The development of a strategy for glycolic mitigation was initiated with a system’s engineering workshop. Various chemical and/or physical solutions for how and where to destroy glycolate were considered – consistent with DWPF’s operational capabilities and process requirements. The workshop identified chemical oxidation of glycolate within the DWPF Recycle Collection Tank (RCT) as the most promising option. (The RCT collects offgas condensate from pre-processing, vitrification, and other unit operations performed in DWPF and is the singular return vessel delivering recycle effluent back to CSTF.) A series of down-select experimental tests were performed that showed sodium permanganate was the most effective oxidant. This work was performed to identify an appropriate operational protocol for DWPF implementation. Building upon the downselect experiments, the work targeted an improved description of suitable RCT conditions prior to the strike (pH, etc.), permanganate addition rate, and destruction reaction kinetics. Data collected were also used to determine the best expression of reaction stoichiometry and the effective minimum permanganate addition required.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Formation of Organic Acids and Carbonyl Compounds in n ‐Butane Oxidation via γ‐Ketohydroperoxide Decomposition

Abstract A crucial chain‐branching step in autoignition is the decomposition of ketohydroperoxides (KHP) to form an oxy radical and OH. Other pathways compete with chain‐branching, such as “Korcek” dissociation of γ‐KHP to a carbonyl and an acid. Here we characterize the formation of a γ‐KHP and its decomposition to formic acid+acetone products from observations of n ‐butane oxidation in two complementary experiments. In jet‐stirred reactor measurements, KHP is observed above 590 K. The KHP concentration decreases with increasing temperature, whereas formic acid and acetone products increase. Observation of characteristic isotopologs acetone‐ d 3 and formic acid‐ d 0 in the oxidation of CH 3 CD 2 CD 2 CH 3 is consistent with a Korcek mechanism. In laser‐initiated oxidation experiments of n ‐butane, formic acid and acetone are produced on the timescale of KHP removal. Modelling the time‐resolved production of formic acid provides an estimated upper limit of 2 s −1 for the rate coefficient of KHP decomposition to formic acid+acetone.

Popolan‐Vaida, Denisia M.↗