Microfluidic System for CO 2 Reduction to Hydrocarbons (Phase II Final Report)
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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Results for “formic acid”
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Nuclear-Driven Chemical Conversion Pathways
The purpose of this work is to explore the possibilities of using coal as a carbon resource by converting it to fuels and chemicals with heat from a nuclear power plant. While many previous studies have focused on coal gasification, this process requires combusting a portion of the coal and producing heat. By employing pyrolysis over gasification, the energy content in the coal can be preserved. Pyrolysis of coal also results in a large portion of solid char, which can be converted to activated carbon and sold to various markets. This model uses hydrogen produced by nuclear-supplied heat and electricity to convert the syngas stream to methanol, which has many pathways for further processing into fuels, chemicals, and plastics. Specifically, this project focuses on non-fuel products for methanol pathways. The CO2 captured within the refinery model can also be combined with hydrogen to produce more chemical products and reduce CO2 emissions.
01 COAL, LIGNITE, AND PEAT↗
Highlights: Model documentation and validation for chemical conversion processes added to the HYBRID library
These are slides containing highlights from INL/RPT-23-75961-Rev000 Model documentation and validation for chemical conversion processes added to the HYBRID library.
01 COAL, LIGNITE, AND PEAT↗
Structure and Stability of Pristine and Carboxylate-Covered Anatase TiO 2 (001) in Aqueous Environment
The interactions of carboxylic acids and water with TiO 2 surfaces are important in applications ranging from solar cells to biomedical devices. Here we focus on the aqueous interface with the minority (001) surface of anatase TiO 2 (A-001) and the behavior of adsorbed formic and acetic acid monolayers at this interface. We investigated the structure and stability of the pristine reconstructed and formic/acetic acid covered A-001 surfaces in contact with water using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. The (1 × 4) reconstruction of the pristine surface is found to be stable in aqueous environment, within the time scale of our simulation. Here, carboxylic acids adsorb in deprotonated bidentate (BD) form on A-001, with the dissociated proton transferred to a surface oxygen to form a bridging hydroxyl. Of the two possible configurations, BD bridging and BD straddling, of the adsorbed species, the latter is found to rapidly transform to a monodentate structure during our simulations. Further investigation of mixed acetate–formate monolayers on A-001 in water indicates that also BD bridging species can become unstable at the boundaries between formate and acetate-covered regions, transforming to a monodentate form that does not prevent water adsorption on the TiO 2 surface.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Spin-orbit coupling in molecular complexes beyond van der Waals regime: Key factors for further splitting of 2 P 3/2 ground state
Here, we report a joint spectroscopic and theoretical study probing spin-orbit coupling (SOC) in a variety of molecular complexes between an iodine atom and a ligand (L) with L ranging from Ar, HF to formic/acetic acids, and glycine/N-methylated glycine derivatives. Cryogenic photoelectron spectroscopy of L·I - (L=HCOOH, CH 3 COOH) reveals three distinct peaks, identified as three SOC states, denoted as X(1/2), A(3/2), and B(l/2) for the corresponding neutrals. The X and A separation ΔE XA is measured to be 0.10 eV for both, whereas the X and B gap ΔE XB is 0.98 and 0.97 eV for formic and acetic acid, respectively. These new ΔE XA values are compared with the previously reported values for the molecular complexes L·I· with L=Ar, HF, glycine, and A-methylated glycines. All together these complexes encompass a diversity of intermolecular interactions, from van der Waals to weak and strong hydrogen bonding. While the ΔE XB remains similar, the ΔE XA is shown to be extremely sensitive to the type of ligands and interactions, spanning from 5 meV to 150 meV. High-level relativistic quantum calculations including explicit SOC formulism nicely reproduce all experimental SOC splitting. A direct correlation between the magnitude of ΔE XA with the intermolecular interaction strength or bond distance of the neutral complexes—the stronger interaction (shorter bond length), the greater splitting, is established.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Corrosion of Ferrous Structural Alloys in Biomass Derived Fuels and Organic Acids
This work investigated the corrosivity of biomass-derived liquid fuels and organic acids associated with bio-oils and conducted a corrosion compatibility evaluation of several structural ferrous alloys in the fuels and acids. Here, the acidity parameters and solution conductivity values were higher in raw pyrolysis bio-oils than postprocessed oils with significant corrosion attack for carbon steel and Fe-2.25Cr-1Mo. However, higher-grade stainless steels, ferritic Fe-15Cr (15Cb) and austenitic types 304L and 316L, showed negligible corrosion loss, whereas lower-Cr ferritic grades 409, 410, and 416 were attacked. Metal leaching tests and electrochemical impedance spectroscopy measurements revealed superior corrosion resistance of 316 over 410 stainless steels in solutions of formic and oxalic acids that can be present in bio-oils. The corrosion evaluation methods utilized in this work provide effective screening tools to identify the compatible structural alloys for bio-oils.
09 BIOMASS FUELS↗
Understanding Adsorption and Reactions at Aqueous Oxide Interfaces with Neural Network Potential Molecular Dynamics
Chemical processes at metal oxide−water interfaces are of central importance in geochemistry, biology, and energy technologies. A better understanding of these processes would allow us to make a significant step toward optimizing and controlling them, which could in turn lead to broader impacts. Computational modeling is indispensable to accomplishing this task because complexity and disorder often make it difficult to extract atomistic information from experiments. Balancing computational cost and accuracy, simulation schemes based on efficient machine learning representations of the potential energy surface (PES) predicted by ab initio calculations have become increasingly popular over the past decade. In particular, several studies have demonstrated the ability of machine learning models to accurately reproduce the complex ab initio PESs of aqueous oxide interfaces, allowing simulations of systems and processes that are not accessible with ab initio methods. In this Account, we review our recent efforts to understand adsorption processes and reactions at aqueous oxide interfaces using deep potential molecular dynamics (DPMD), a simulation scheme employing deep neural networks (DNNs), which has proven to be quite successful in accurately describing many different systems in the condensed phase. After summarizing the DPMD methodology, we first review our work on the acid−base chemistry of oxide surfaces in contact with water, a fundamental characteristic that controls proton transfer and surface charge at the interface. We focus on the aqueous interface of rutile IrO 2 , an oxide material thus far considered the best catalyst for the oxygen evolution reaction (OER). We show that this interface is characterized by a large fraction of dissociated water and a strong Brønsted acidity of the surface sites, in good agreement with the experimentally measured value of the point of zero proton charge. In our second example, we investigate how the adsorption of organic species from ambient air or water affects the structure and wettability of the aqueous interfaces of TiO 2 , a prototypical photocatalytic material. This is a question that is relevant to understanding the UV-induced hydrophilicity of TiO 2 surfaces, a property at the basis of self-cleaning windows and related applications. Specifically focusing on formic and acetic acids, the two most common atmospheric organic acids, our simulations reveal that these acids control the wettability of TiO 2 largely through acid−base chemistry at the interface rather than chemisorption on the oxide surface, a finding that could help improve the design of self-cleaning surfaces and photocatalytic devices. Finally, we review our recent study of methanol at TiO 2 −water interfaces, a system whose interest is largely motivated by the role of methanol in enhancing photocatalytic hydrogen evolution on TiO 2 . Our simulations provide mechanistic insights into the coupled roles of the organic adsorbate and water at the TiO 2 interface, with implications for how methanol enhances the activity of H 2 evolution.
adsorption↗
Organic Acid-Assisted Thermal Dehalogenation of Halide Salt Nuclear Wastes: From Waste Salts to Borosilicate Glass
Only a handful of high-halide salt waste forms have been demonstrated for vitrification-based immobilization strategies for halide-salt nuclear waste streams (e.g., pyroprocessing wastes, molten salt reactor wastes) and they all have low waste loading potential and most have low chemical durabilities for high-alkali streams. An alternative approach to direct salt immobilization is salt partitioning prior to waste form fabrication and one option for partitioning is halide removal (called dehalogenation). Removing the halogen fraction through dehalogenation can significantly reduce the waste volume required for disposal in the primary waste form. Furthermore, when dehalogenation is performed using organic acids, the dehalogenation reagent can decompose during high-temperature vitrification, reducing waste loading limitations in the waste form. In the current work, different organic acids (i.e., oxalic, formic, acetic, oxamic, and citric) were evaluated for dehalogenation efficiency of a simple chloride salt simulant (7.19% LaCl 3 , 53.77% LiCl, and 39.04% KCl, by mole) and a more complex chloride salt simulant called ERV3 (electrorefiner version 3) at 150 °C–300 °C and using H + /Cl – molar ratios of 1:1, 2:1, and 3:1. Additionally, a borosilicate glass waste form called TARS (or the average of refined specifications) was formulated, produced, and characterized for dehalogenated ERV3.
Amorphous materials↗
Low-temperature (< 200 °C) degradation of electronic nicotine delivery system liquids generates toxic aldehydes
Electronic cigarette usage has spiked in popularity over recent years. The enhanced prevalence has consequently resulted in new health concerns associated with the use of these devices. Degradation of the liquids used in vaping have been identified as a concern due to the presence of toxic compounds such as aldehydes in the aerosols. Typically, such thermochemical conversions are reported to occur between 300 and 400 °C. Herein, the low-temperature thermal degradation of propylene glycol and glycerol constituents of e-cigarette vapors are explored for the first time by natural abundance 13 C NMR and 1 H NMR, enabling in situ detection of intact molecules from decomposition. The results demonstrate that the degradation of electronic nicotine delivery system (ENDS) liquids is strongly reliant upon the oxygen availability, both in the presence and absence of a material surface. When oxygen is available, propylene glycol and glycerol readily decompose at temperatures between 133 and 175 °C over an extended time period. Among the generated chemical species, formic and acrylic acids are observed which can negatively affect the kidneys and lungs of those who inhale the toxin during ENDS vapor inhalation. Further, the formation of hemi- and formal acetals is noted from both glycerol and propylene glycol, signifying the generation of both formaldehyde and acetaldehyde, highly toxic compounds, which, as a biocide, can lead to numerous health ailments. The results also reveal a retardation in decomposition rate when material surfaces are prevalent with no directly observed unique surface spectator or intermediate species as well as potentially slower conversions in mixtures of the two components. The generation of toxic species in ENDS liquids at low temperatures highlights the dangers of low-temperature ENDS use.
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Approaches to investigate the role of chelation in the corrosivity of biomass-derived oils
The need to provide the U.S. market with a renewable liquid fuel energy source from a non-food feedstock stream has gained considerable traction due to benefits such as improved energy efficiency, reduced environmental impacts, and enhanced national security. Practical achievement of these goals via biomass and bio-waste utilization involves production of liquid intermediates containing corrosive, reactive species like carboxylic acids, ketones, aldehydes, and hydroxyaldehydes. Such mixtures challenge materials of containment, processing, and transport. It is widely recognized that the smaller organic acids, such as acetic and formic, are corrosive and can remove protective surface oxides on alloys used in bio-oil processing infrastructure, and ketones can swell sealing polymers. However, literature shows, and findings herein confirm, larger carboxylic acids and bidentate alcohols are present. This highlights the potential for synergistic, detrimental effects of constituents in bio-oil corrosion, including direct reactivity of small acids compounded with the possibility of mobilization of protective metal oxide layers via chelation by larger acids and oxygenates. The question of whether species beyond small acids can significantly contribute to corrosion requires analytical approaches previously not applied to bio-oil corrosion studies and certainly not previously applied corroboratively. As such, this work introduces a combination of optical, mass spectral, and electrochemical impedance spectroscopies with an incubation approach to study metal mobilization, to facilitate elucidating chelation's role in bio-oil corrosive pathways. To enable systematic study of these oxygenates' material compatibility individually and in combination, a model matrix of bio-oil constituents was also developed based on identification of key components of real bio-oils.
09 BIOMASS FUELS↗
Clean and High-Efficiency Natural Gas Furnace with Advanced Acidic Gas Trap Technology
Ccurrent natural gas condensing furnaces generate substantial acidic condensate and SOx/NOx/CO/HC/methane emissions, causing long-term environment issues related to air, water and soil. Acidic condensate occurs when flue gases within the furnaces cool down below the dew points of acidic gases, which upon condensation, combine with water vapor to produce acidic solutions. The acidic condensate causes serious corrosion and fouling problems in natural gas condensing furnaces. This paper presents a novel solution to use an advanced adsorption technology based on monolithic acidic gas trap (AGT) adsorbers for SOx trapping, NOx redox, and formic acid/CO/HC/methane oxidation, enabling a new natural gas furnace with utra-clean flue gas and neutral condensate. When the AGT adsorber is appropriately integrated with natural gas furnaces, the acidic gases of SOx, NOx and formic gas/CO/HC will be continuously adsorbed, redoxed or oxidized, respectively, from the flue gas during a regular heating season, except for occasional regeneration activities for SOx trapping. In the paper, we present results from a prototype furnace employing the novel AGT component, which enables a pH of the condensate =7, NOx emissions of 1-2 nanograms/joule and an annual fuel utilization efficiency (AFUE) of 96%, providing a cost-effective technology for condensing furnaces that is eco-friendly to the environment.
Gao, Zhiming↗
Monolithic gas trap adsorber for high efficiency, cost effective, low-emission condensing furnace
An improved method and system for treating flue gases from a natural gas furnace are provided. The method and system include an acidic gas trap (AGT) adsorber which enables the continuous adsorption and storage of SOx, NOx redox, and formic acid/CO/HC/CH 4 oxidation, with a negligible pressure drop. The AGT adsorber includes a catalyst coating having a nanotube structure (e.g., a uniform nanostructure forest coating) or a uniform porous nanostructure of various low-cost oxides through scalable low temperature solution processes, including oxides of Ti, Cu, Ba, Mn, Zr, Zn, Sr, Ca, Li, K, Na, Al, or Ce.
Gao, Zhiming↗
Mercury Testing with Sludge Batch 10 Tank 40 Simulant
Savannah River Mission Completion (SRMC) requested that researchers at Savannah River National Laboratory (SRNL) perform testing designed to examine why the Defense Waste Processing Facility (DWPF) is not collecting elemental mercury in the Mercury Water Wash Tank (MWWT). In order for DWPF to recover mercury, mercuric oxide must first be reduced to elemental mercury. The elemental mercury must then be steam stripped, condense, and coalesce in the Mercury Water Wash Tank (MWWT) during chemical processing in the Sludge Receipt and Adjustment Tank (SRAT). The efficiency of these steps was investigated in a series of laboratory scale SRAT experiments under the nitric-glycolic and nitric-formic flowsheets utilizing Momentive Y-17112 and Antifoam 747. Mercury speciation in the Slurry Mix Evaporator Condensate Tank (SMECT) and condensate streams was also examined. The key conclusions from these experiments are as follows: Mercury II Oxide may not be fully reduced to elemental mercury during acid addition at 93°C. Higher temperatures, i.e., boiling may be necessary to fully reduce Mercury II Oxide. The highest percent mercury recovery (71 %) in the MWWT was observed in the MS-NGA-17112 experiment (nitric-glycolic acid flowsheet with Momentive Y-17112), which is how DWPF is currently operating the SRAT.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗