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At least 397 records · Page 22

Testing Rod Seal Leakage of a 700 HP Reciprocating Compressor

Methane emissions from reciprocating compressors in the U.S. natural gas industry account for over 72.4 Bcf per year according to a 2006 statement by the United States Environmental Protection Agency. Methane also has a global warming potential 50 times greater than carbon monoxide. Reciprocating compressors are the machinery type with the highest contribution to methane emissions at natural gas transmissions stations. The largest contributing factor comes from the sealing components in the packing components around the piston rod. SwRI, therefore, designed and setup a test loop to perform baseline packing leakage measurements on a four stage 700 HP JGT/4 compressor. The goal was to improve upon current packing leakage models and to compare new seals vs. used seals. The test loop design is described including the limits of operation. The Data Acquisition System (DAQ), including data measurements, is also fully described. The project shows the results of the commissioning process that verified the operation of all the components. Once the loop was commissioned, SwRI performed baseline packing leakage for multiple pressure ratios on each of the four stages of the compressor. The data was collected to develop an analytical model of the packing leakage. Finally, similar testing was performed after replacing the typical rod seal packing with used packing. The used packing leakage was compared to the baseline packing leakage.

03 NATURAL GAS↗

Internal combustion engine as a chemical reactor to produce synthesis gas from hydrocarbon feeds

An internal combustion engine is operated at fuel-rich conditions by adjusting one or more operating parameters such as, for example, a throttle, an ignition timing, a load coupled to the engine, a fuel pressure, power to a supercharger, and power to a preheater to maintain a specified engine speed and a temperature of an exhaust gas. Operating the engine under these conditions allows the engine to function as a reformer producing a synthesis gas comprising hydrogen and carbon monoxide.

Carpenter, III, John Reeves↗

Catalysts and process for liquid hydrocarbon fuel production

The present invention provides a novel process and system in which a mixture of carbon monoxide and hydrogen synthesis gas, or syngas, is converted into hydrocarbon mixtures composed of high quality gasoline components, aromatic compounds, and lower molecular weight gaseous olefins in one reactor or step. The invention utilizes a novel molybdenum-zeolite catalyst in high pressure hydrogen for conversion, as well as a novel rhenium-zeolite catalyst in place of the molybdenum-zeolite catalyst, and provides for use of the novel catalysts in the process and system of the invention.

White, Mark G.↗

Idaho National Laboratory Annual Report for Permit to Construct P-2015.0023 for Calendar Year 2020

The U.S. Department of Energy (DOE) Idaho National Laboratory (INL) Site operates facilities with potential emissions criteria and hazardous air pollutants. This report documents the calendar year 2020 criteria and hazardous air pollutants emissions and has been prepared to comply with permit to construct (PTC) P-2015-0023, Condition 2.9 and Idaho Administrative Procedures Act (IDAPA) 58.01.01.178, Standard Contents of Permits Establishing a Facility Emissions Cap (FEC). IDAPA 58.01.01.178.04 requires that all permits establishing a FEC shall include sufficient reporting to assure compliance with the permit establishing the FEC. Total hazardous air pollutant (HAP) emissions for the year were 0.59 tons in aggregate and the maximum individual HAP was hydrochloric acid at 0.35 tons. Criteria pollutant emissions were 1.23 tons for sulfur dioxide, 40.96 tons for oxides of nitrogen, 11.7 tons of carbon monoxide, 3.01 tons of total particulate matter and 1.98 tons of volatile organic compounds (VOC).

99 GENERAL AND MISCELLANEOUS↗

Enhancing Electrochemical CO2 Conversion by Controlling Electrocatalysts' Structure

Electrochemical reduction of CO2 (CO2R) to valuable, carbon-neutral chemical feedstocks and storable fuels driven by renewable electricity has been recognized as one of the promising pathways to mitigate the greenhouse effect, reduce global demand for fossil fuels, achieve carbon neutrality, and create sustainable energy. Tremendous ongoing efforts have focused on controlling the morphology, composition, structure, size, defects, etc., of the electrocatalysts to improve product selectivity, activity, and durability to approach the feasibility of practical applications (current density higher than 200 mA/cm2 and lifetime ~1,000 hr+). This presentation will discuss how the geometry and surface composition of novel copper- and tin-based catalysts would maximize the CO2 conversion to carbon monoxide and liquid formic acid/formate in both common aqueous H-cell and electrolyzer configurations. Several spectroscopic, microscopic, and electrochemical characterization tools have been utilized to correlate the changes in the structural, physico-chemical, and electronic properties with the catalytic activity. Our work provides additional electrocatalyst design considerations for high-performance CO2 electrolysis.

Nguyen Phan, Thuy Duong↗

Annual FEC-PTC Report - CDRL F.70

The U.S. Department of Energy (DOE) Idaho National Laboratory (INL) Site operates facilities with potential emissions of criteria and hazardous air pollutants. This report documents the calendar year 2021 criteria and hazardous air pollutants emissions and has been prepared to comply with permit to construct (PTC) P-2015.0023 for the period of 1-1-2021 up to the effective date of PTC P 2020.0045 (1-29-2021), and PTC P-2020.0045 for the period from 1-29-2021 through 12-31-2021. The Idaho Administrative Procedures Act (IDAPA) 58.01.01.178, Standard Contents of Permits Establishing a Facility Emissions Cap (FEC) requires that all permits establishing a FEC shall include sufficient reporting to assure compliance with the permit establishing the FEC. Total hazardous air pollutant (HAP) emissions for the year were 0.10 tons in aggregate and the maximum individual HAP was toluene at 0.04 tons. Criteria pollutant emissions were 0.75 tons for sulfur dioxide, 24.33 tons for oxides of nitrogen, 6.07 tons of carbon monoxide, 2.53 tons of total particulate matter and 0.99 tons of volatile organic compounds (VOC).

99 GENERAL AND MISCELLANEOUS↗

Hydrothermally and thermally stable catalytic materials based on theta-alumina

A material and a method of making hydrothermally stable (catalytic) materials on the basis of theta-alumina support that is thermally and hydrothermally stable up to 1,150 C with metal, mixed metal-, metal-oxide nanoparticles dispersed upon it. Such materials did not lose significant amounts of their catalytic activity at temperature ranges for industrially relevant applications (including hydrocarbon oxidation, nitric oxide reduction, carbon monoxide oxidation) even after hydrothermal aging up to 1,150° C.

Khivantsev, Konstantin↗

A New Window into the Baryon Cycle at Cosmic Noon with Line Intensity Mapping: Forecasts for auto- and cross-correlations in [CII]-158$μ$m, HI 21 cm, CO$_{J+1\rightarrow J}$, and H$α$ galaxies

Across the peak of cosmic star formation at $z\sim1-2$, inflow, processing, and feedback drive rapid changes in the spatial distribution and chemical composition of baryons in galaxies and surrounding reservoirs; this baryon cycle can be tomographically mapped by line intensity mapping (LIM) of atomic hydrogen, ionized carbon, and carbon monoxide. We present a simulation-based forecasting framework for detecting auto- and cross-power spectra between spectroscopic surveys of four such tracers at $z\sim0.5-1.7$ mapping the same deep field - TIM, EoRSpec/FYST, MeerKAT, & Euclid. We forward-model 3-D distributions for these tracers from magnetohydrodynamic simulations, directly capturing the two-halo, one-halo, and shot statistics without relying on analytical decompositions. We further detail a signal-to-noise formalism, tailored to LIM surveys with highly anisotropic geometries and Fourier-space coverage. We demonstrate that galaxy cross-correlations will be the dominant discovery channel for current-generation surveys. These instruments will detect the auto-spectra for CO and HI 21 cm and the CO $\times$ 21 cm cross-spectrum at modest S/N $\sim 1-10$, while placing upper limits on the [CII]-158$μ$m signals. [CII], CO, and HI LIM will be $\sim3-30\times$ ($0.5-1.5$ dex) more sensitive to cross-correlation with the Euclid survey, however, than their respective auto-correlations, constraining all three models of line emission at high significance (S/N $\sim 10-40$) within this decade. Finally, we formulate a staged instrumental trajectory with planned or reasonable improvements, including the as-proposed SKA-Mid. We forecast advancing the per-$k$-mode sensitivities of each auto-, galaxy-line, and line-line spectrum by several orders of magnitude, enabling new percent- and sub-percent level constraints on cosmology and the redshift evolution of star formation and the baryon cycle.

Agrawal, Shubh [Pennsylvania U., Dept. Math.]↗

2025 ASMS Investigation of the Collision-Induced Dissociation Mechanism of Protonated TODGA with IRIS

Title (20 words): Investigation of the Collision-Induced Dissociation Mechanism of Protonated TODGA with IRIS Introduction (120 words): One of the challenges facing wide-spread adoption of nuclear power is the development of efficient separation processes for used nuclear fuel. The molecules in separation processes are subjected to an extreme environment due to the high radiation fields from the used fuel and highly acidic media used for fuel dissolution, which results in significant molecular degradation, leading to reduced process efficiency. These degradation products must be identified and studied so mitigation strategies can be developed to maintain process efficiency. However, complex systems can have many degradation products, complicating identification. Untargeted analysis tools could be used to understand radiation chemistry in complex systems. However, this would necessitate improved understanding of the gas-phase fragmentation mechanisms of fuel cycle molecules like tetraoctyldiglycolamide (TODGA). Methods (120 words): The gas-phase fragmentation of protonated TODGA was investigated using collision-induced dissociation (CID), resonance ejection, and infrared ion spectroscopy (IRIS). CID and resonance ejection experiments were conducted using a Bruker Daltonics (Bremen, Gemany) SolariX XR fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. IRIS spectra of protonated TODGA and its two CID fragmentation products were measured using a modified Bruker amaZon Speed ETD 3D quadrupole ion trap mass spectrometer coupled to the Free Electron Lasers for Infrared eXperiments (FELIX) free electron laser. Measured spectra were compared with density functional theory (DFT) calculations using the Gaussian 16, Revision C.02 software package with the ?B97X-D functional and def2-TZVPP basis sets. Candidate structures were generated using the CREST 3.0 conformational sampling software tool. Preliminary Data (300 words): Collision-induced dissociation of protonated TODGA ([C36H73N2O3]+, m/z=581.562) results two fragment ions, one at m/z=340.285 assigned as [C20H38NO3]+ and the other at m/z=312.290, assigned as [C19H38NO2]+. Based on the assigned formula and the structure of protonated TODGA, the fragment at m/z=340.285 is likely formed from elimination of neutral dioctylamine. Comparison of the IRIS spectrum of m/z=340.285 with DFT predictions suggests it contains a ring structure, and is assigned as N-octyl-N-(6-oxo-1,4-dioxan-2-ylidene)octan-1-aminium. Based on this structure and the structure of protonated TODGA, we hypothesize this fragment formed from elimination of neutral dioctylamine followed by a ring closure mechanism. Comparison of the IRIS spectrum of the fragment at m/z=312.290 with DFT predictions also indicated the presence of a ring structure, assigned as N-(1,3-dioxolan-4-ylidene)-N-octyloctan-1-aminium. This product could be formed from elimination of carbon monoxide from the ring of m/z=340.285 as a sequential fragmentation or formed directly from protonated TODGA via elimination of neutral N,N-dioctylformamide followed by a ring closure. Resonance ejection experiments where m/z=340 was continuously ejected from the IRC cell showed no decrease in intensity of m/z=312.290 across several collision energies, suggesting that the later, direct formation mechanism, dominates. The location of the ionizing proton in protonated TODGA is important for modeling the fragmentation mechanisms. DFT calculations suggested that the position of bands involving the coupled vibrations of the amide C—N and C=O bonds in TODGA are the most sensitive to proton location. Evaluation of the IRIS spectrum of protonated TODGA suggests that the ionizing proton is located between the two amid oxygens. This protonation location was calculated to lie approximately 30 kJ/mol lower in energy than the next lowest energy location, with the proton located solely on one of the amide oxygens. Novel aspect (20 words): Infrared ion spectroscopy combined with resonance ejection experiments and density functional theory to probe the collision-induced dissociation mechanism of tetraoctyldiglycolamide.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗

Influence of Operating Conditions on Ethanol Passive Prechamber Cold-start Operation

Cold-start operation in spark ignition engines is characterized by many drawbacks such as poor fuel vaporization, substantial wall film formation, and weak ignition which can result in unstable combustion and high concentrations of carbon monoxide (CO), nitrogen oxides (NOx), and unburnt hydrocarbons (UHC) prior to catalyst light-off. These challenges are particularly important for ethanol as the fuel’s high latent heat of vaporization and low vapor pressure can hinder reliable ignition during cold-start. In this context, passive prechamber ignition systems offer a viable pathway to improve ignitability by producing hot turbulent jets that can promote combustion in the main chamber. In this study, the influence of operating conditions on jet formation and combustion characteristics in an ethanol-fueled passive prechamber spark ignition engine is investigated. Two intake pressures (40 kPa and 60 kPa) and two engine speeds (450 and 600 rpm) are studied to represent various stages of the cold-start ramp-up. Results indicate that lower intake pressures lead to delayed and asymmetric turbulent jet formation, and lower peak heat release rates. Lower engine speeds, on the other hand, produced higher peak heat release and faster combustion due to greater residence time in the engine. This greater residence time also increases the likelihood of autoignition in the main chamber, potentially promoting quicker heat release for lower engine speeds. These results provide insight into the role of operating conditions on cold-start ramp-up of passive prechamber engines.

Banagiri, Shrikar [ORNL] (ORCID:0000000239745099)↗

PdAu/YSZ composite hydrogen separation membranes with enhanced stability in the presence of CO

The effects of gold composition on the tolerance of palladium-based composite membranes to CO exposure was studied under the presence of high CO concentrations. Membranes with PdAu compositions ranging up to 41% by mass were exposed to binary 50/50 H 2 /CO gas atmospheres and both hydrogen flux and purity were monitored over time. It was observed that the highest gold composition (41%) suffered no degradation in membrane performance in terms of permeate hydrogen purity and hydrogen permeation flux during the 48 h exposure. Furthermore, for lower gold compositions, X-ray diffraction patterns suggested that carbon entered the film and could be removed by exposure to a non-CO containing gas mixture over time. However, removal of the carbon adversely affected purity; interestingly, some of the purity decline could be reversed upon re-exposure to the CO gas mixture. It is hypothesized that carbon loading in the palladium films causes lattice expansion and may even fill pore defects, thus lowering leaks through the Pd films. Furthermore, this study suggests that a membrane exposed to a CO mixture should not be cycled between CO and non-CO environments, but rather run continuously for best performance. Additionally, the choice of Pd-alloy and metal composition should be considered in regard to its carbon solubility to best predict lifetime performance.

08 HYDROGEN↗

Non-equilibrium plasma co-upcycling of waste plastics and CO 2 for carbon-negative oleochemicals

Mechanical recycling and chemical upcycling by thermochemical reactions have been the major approaches for recycling end-of-life plastics. Herein, we report an electrified approach to upcycle waste plastics into carbon-negative commodity chemicals using greenhouse gas CO 2 as the oxidant and additional carbon source. In this non-equilibrium plasma process, waste polyolefins were oxidatively depolymerized by plasma-activated CO 2 to produce oleochemicals and hydrocarbon chemicals in a single-step process at high reaction rates. In addition, a mixture of CO 2 and a small amount of O 2 was employed as plasma gases to selectively produce fatty alcohols from polyolefins. Based on this atmospheric pressure, non-solvent, and non-catalyst process, up to 97.6% of fatty alcohols could be produced within minutes. In this article, the co-conversion approach was demonstrated using common polyolefins and real-world mixed waste plastics to obtain comparable results. The techno-economic analysis estimates the internal rate of return to be 42.2% and 43.5% for the plasma-based conversion of waste plastics, depending on the plasma gas composition. Lifecycle assessment indicates the global warming potential is between −3.33 and −3.07 kg CO 2e per kg of plastic.

42 ENGINEERING↗

A Pressure-Swing Process for Reactive CO2 Capture and Conversion to Methanol through Precise Control of Co-Located Active Sites in Dual Functional Materials

The goals of this project are to design and develop tailored dual-functional materials (DFMs) and the accompanying pressure-swing process for the reactive capture and conversion (RCC) of CO 2 to methanol, a vital product in the chemical market and a versatile precursor to fuels. Throughout this project, NREL researcher team has successfully developed 2 groups of DFM and associated cyclic RCC procedure to selectivity produce either methanol or CO, which is a major intermediate for methanol synthesis with commercially available technologies.

01 COAL, LIGNITE, AND PEAT↗

A Bifunctional Ionic Liquid for Capture and Electrochemical Conversion of CO 2 to CO over Silver

Electrochemical conversion of CO 2 requires selective catalysts and high solubility of CO 2 in the electrolyte to reduce the energy requirement and increase the current efficiency. In this study, the CO 2 reduction reaction (CO 2 RR) over Ag electrodes in acetonitrile-based electrolytes containing 0.1 M [EMIM][2-CNpyr] (1-ethyl-3-methylimidazolium 2-cyanopyrolide), a reactive ionic liquid (IL), is shown to selectively (>94%) convert CO 2 to CO with a stable current density (6 mA·cm –2 ) for at least 12 h. The linear sweep voltammetry experiments show the onset potential of CO 2 reduction in acetonitrile shifts positively by 240 mV when [EMIM][2-CNpyr] is added. This is attributed to the pre-activation of CO 2 through the carboxylate formation via the carbene intermediate of the [EMIM] + cation and the carbamate formation via binding to the nucleophilic [2-CNpyr] – anion. The analysis of the electrode–electrolyte interface by surface-enhanced Raman spectroscopy (SERS) confirms the catalytic role of the functionalized IL where the accumulation of the IL-CO 2 adduct between –1.7 and –2.3 V vs Ag/Ag + and the simultaneous CO formation are captured. Furthermore, this study reveals the electrode surface species and the role of the functionalized ions in lowering the energy requirement of CO 2 RR for the design of multifunctional electrolytes for the integrated capture and conversion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

An alcove at the acetyl-CoA synthase nickel active site is required for productive substrate CO binding and anaerobic carbon fixation

One of the seven natural CO 2 fixation pathways, the anaerobic Wood-Ljungdahl pathway (WLP) is unique in generating CO as a metabolic intermediate, operating through organometallic intermediates, and in conserving (versus utilizing) net ATP. The key enzyme in the WLP is acetyl-CoA synthase (ACS), which uses an active site [2Ni-4Fe-4S] cluster (A-cluster), a CO tunnel, and an organometallic (Ni-CO, Ni-methyl, and Ni-acetyl) reaction sequence to generate acetyl-CoA. Here, we reveal that an alcove, which interfaces the tunnel and the A-cluster, is essential for CO 2 fixation and autotrophic growth by the WLP. In vitro spectroscopy, kinetics, binding, and in vivo growth experiments reveal that a Phe229A substitution at one wall of the alcove decreases CO affinity thirty-fold and abolishes autotrophic growth; however, a F229W substitution enhances CO binding 80-fold. Our results indicate that the structure of the alcove is exquisitely tuned to concentrate CO near the A-cluster; protect ACS from CO loss during catalysis, provide a haven for inhibitory CO, and stabilize the tetrahedral coordination at the Nip site where CO binds. The directing, concentrating, and protective effects of the alcove explain the inability of F209A to grow autotrophically. The alcove also could help explain current controversies over whether ACS binds CO and methyl through a random or ordered mechanism. Our work redefines what we historically refer to as the metallocenter "active site". The alcove is so crucial for enzymatic function that we propose it is part of the active site. The community should now look for such alcoves in all "gas handling" metalloenzymes.

bacterial metabolism↗

Designing a Zn–Ag Catalyst Matrix and Electrolyzer System for CO 2 Conversion to CO and Beyond

CO 2 emissions can be transformed into high-added-value commodities through CO 2 electrocatalysis; however, efficient low-cost electrocatalysts are needed for global scale-up. Inspired by other emerging technologies, the authors report the development of a gas diffusion electrode containing highly dispersed Ag sites in a low-cost Zn matrix. Here, this catalyst shows unprecedented Ag mass activity for CO production: –614 mA cm –2 at 0.17 mg of Ag. Subsequent electrolyte engineering demonstrates that halide anions can further improve stability and activity of the Zn–Ag catalyst, outperforming pure Ag and Au. Membrane electrode assemblies are constructed and coupled to a microbial process that converts the CO to acetate and ethanol. Combined, these concepts present pathways to design catalysts and systems for CO 2 conversion toward sought-after products.

36 MATERIALS SCIENCE↗

A Metal-Organic Framework (MOF)-Based Multifunctional Cargo Vehicle for Reactive-Gas Delivery and Catalysis

The efficient delivery of reactive and toxic gaseous reagents to organic reactions was studied using metal-organic frameworks (MOFs). The simultaneous cargo vehicle and catalytic capabilities of several MOFs were probed for the first time using the examples of aromatization, aminocarbonylation, and carbonylative Suzuki–Miyaura coupling reactions. These reactions highlight that MOFs can serve a dual role as a gas cargo vehicle and a catalyst, leading to product formation with yields similar to reactions employing pure gases. Furthermore, the MOFs can be recycled without sacrificing product yield, while simultaneously maintaining crystallinity. Our reported findings were supported crystallographically and spectroscopically (e.g., diffuse reflectance infrared Fourier transform spectroscopy), foreshadowing a pathway for the development of multifunctional MOF-based reagent-catalyst cargo vessels for reactive gas reagents as an attractive alternative to the use of toxic pure gases or gas generators.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗