Controlled Synthesis of Nanosized Palladium icosahedra and Their Catalytic Activity towards Formic-Acid Oxidation
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Tian, Lv↗
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SBIR Phase IIB: Cells, Membranes, and Separators for Carbon Dioxide Conversion to Formic Acid
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10 SYNTHETIC FUELS↗
Syringe Dispense Printing of Copper Paste and Formic Acid Vapor Sinter.
Abstract not provided.
Lavin, Judith Maria↗
Oxide-Derived Tin Microspheres for Efficient CO2 Electroreduction to Formic Acid
Presented by LRST at the AIChE 2020 Annual Meeting, 11/17
Nguyen-Phan, Thuy-Duong↗
Implementation of flowsheet change to minimize hydrogen and ammonia generation during chemical processing of high level waste in the Defense Waste Processing Facility
Testing was completed to develop a chemical processing flowsheet for the Defense Waste Processing Facility (DWPF), designed to vitrify and stabilize high level radioactive waste. DWPF processing uses a reducing acid (formic acid) and an oxidizing acid (nitric acid) to rheologically thin the slurry and complete the necessary acid base and reduction reactions (primarily mercury and manganese). Formic acid reduces mercuric oxide to elemental mercury, allowing the mercury to be removed during the boiling phase of processing through steam stripping. In runs with active catalysts, formic acid can decompose to hydrogen and nitrate can be reduced to ammonia, both flammable gases, due to rhodium and ruthenium catalysis. Replacement of formic acid with glycolic acid eliminates the generation of rhodium- and ruthenium-catalyzed hydrogen and ammonia. In addition, mercury reduction is still effective with glycolic acid. Hydrogen, ammonia and mercury are discussed in the body of the report. Ten abbreviated tests were completed to develop the operating window for implementation of the flowsheet and determine the impact of changes in acid stoichiometry and the blend of nitric and glycolic acid as it impacts various processing variables over a wide processing region. Three full-length 4-L lab-scale simulations demonstrated the viability of the flowsheet under planned operating conditions. The flowsheet is planned for implementation in early 2017.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
The nature of the CO{sub 2}{sup −} radical anion in water
The reductive conversion of CO{sub 2} into industrial products (e.g., oxalic acid, formic acid, methanol) can occur via aqueous CO{sub 2}{sup −} as a transient intermediate. While the formation, structure, and reaction pathways of this radical anion have been modelled for decades using various spectroscopic and theoretical approaches, we present here, for the first time, a vibrational spectroscopic investigation in liquid water, using pulse radiolysis time-resolved resonance Raman spectroscopy for its preparation and observation. Excitation of the radical in resonance with its 235 nm absorption displays a transient Raman band at 1298 cm{sup −1}, attributed to the symmetric CO stretch, which is at ∼45 cm{sup −1} higher frequency than in inert matrices. Isotopic substitution at C ({sup 13}CO{sub 2}{sup −}) shifts the frequency downwards by 22 cm{sup −1}, which confirms its origin and the assignment. A Raman band of moderate intensity compared to the stronger 1298 cm{sup −1} band also appears at 742 cm{sup −1} and is assignable to the OCO bending mode. A reasonable resonance enhancement of this mode is possible only in a bent CO{sub 2}{sup −}(C{sub 2v}/C{sub s}) geometry. These resonance Raman features suggest a strong solute-solvent interaction, the water molecules acting as constituents of the radical structure, rather than exerting a minor solvent perturbation. However, there is no evidence of the non-equivalence (C{sub s}) of the two CO bonds. A surprising resonance Raman feature is the lack of overtones of the symmetric CO stretch, which we interpret due to the detachment of the electron from the CO{sub 2}{sup −} moiety towards the solvation shell. Electron detachment occurs at the energies of 0.28 ± 0.03 eV or higher with respect to the zero point energy of the ground electronic state. The issue of acid-base equilibrium of the radical, which has been in contention for decades, as reflected in a wide variation in the reported pK{sub a} (−0.2 to 3.9), has been resolved. A value of 3.4 ± 0.2 measured in this work is consistent with the vibrational properties, bond structure, and charge distribution in aqueous CO{sub 2}{sup −}.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Chemically Activated Formation of Organic Acids in Reactions of the Criegee Intermediate with Aldehydes and Ketones
Reactions of the Criegee intermediate (CI, .CH2OO.) are important in atmospheric ozonolysis models. In this work, we compute the rates for reactions between .CH2OO. and HCHO, CH3CHO and CH3COCH3 leading to the formation of secondary ozonides (SOZ) and organic acids. Relative to infinitely separated reactants, the SOZ in all three cases is found to be 48–51 kcal mol-1 lower in energy, formed via 1,3- cycloaddition of .CH2OO. across the CQO bond. The lowest energy pathway found for SOZ decomposition is intramolecular disproportionation of the singlet biradical intermediate formed from cleavage of the O–O bond to form hydroxyalkyl esters. These hydroxyalkyl esters undergo concerted decomposition providing a low energy pathway from SOZ to acids. Geometries and frequencies of all stationary points were obtained using the B3LYP/MG3S DFT model chemistry, and energies were refined using RCCSD(T)-F12a/cc-pVTZ-F12 single-point calculations. RRKM calculations were used to obtain microcanonical rate coefficients (k(E)) and the reservoir state method was used to obtain temperature and pressure dependent rate coefficients (k(T, P)) and product branching ratios. At atmospheric pressure, the yield of collisionally stabilized SOZ was found to increase in the order HCHO o CH3CHO o CH3COCH3 (the highest yield being 10-4 times lower than the initial .CH2OO. concentration). At low pressures, chemically activated formation of organic acids (formic acid in the case of HCHO and CH3COCH3, formic and acetic acid in the case of CH3CHO) was found to be the major product channel in agreement with recent direct measurements. Collisional energy transfer parameters and the barrier heights for SOZ reactions were found to be the most sensitive parameters determining SOZ and organic acid yield.
Environmental Molecular Sciences Laboratory↗
Rate Coefficients of C1 and C2 Criegee Intermediate Reactions with Formic and Acetic Acid Near the Collision Limit: Direct Kinetics Measurements and Atmospheric Implications
Rate coefficients are directly determined for the reactions of the Criegee intermediates (CI) CH2OO and CH3CHOO with the two simplest carboxylic acids, formic acid (HCOOH) and acetic acid (CH3COOH), employing two complementary techniques: multiplexed photoionization mass spectrometry and cavity-enhanced broadband ultraviolet absorption spectroscopy. The measured rate coefficients are in excess of 1 1010 cm3 s 1 , several orders of magnitude larger than those suggested from many previous alkene ozonolysis experiments and assumed in atmospheric modeling studies. These results suggest that the reaction with carboxylic acids is a substantially more important loss process for CIs than is presently assumed. Implementing these rate coefficients in global atmospheric models shows that reactions between CI and organic acids make a substantial contribution to removal of these acids in terrestrial equatorial areas and in other regions where high CI concentrations occur such as high northern latitudes, and implies that sources of acids in these areas are larger than previously recognized.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
In-depth investigation on quantitative characterization of pyrolysis oil by 31 P NMR
The characterization of different heteroatom functional groups by employing 31 P NMR has been developed for almost 30 years. In this study, an in-depth investigation of this commonly used method has been accomplished for the analysis of pyrolysis oil. Several commonly used internal standards for 31 P NMR have been examined by in situ monitoring. The results indicated that endo-N-hydroxy-5-norbornene-2,3-dicarboximide (NHND) is not stable after a long period of storage or experiment (>12 hours), but both cyclohexanol and triphenylphosphine oxide (TPPO) can be used as internal standards if a long experiment or storage is required. The pyrolysis oil has also been investigated by both short time (16 hours) in situ monitoring and long time (14 days) ex situ monitoring. The results showed that aliphatic OH, carboxylic acids and water contents are not very stable after 2 hours, and thus a short time of preparation, storage, and experiment need to be considered to ensure a precise quantitative measurement. The decomposition products are still unclear, but some preliminary investigations for different acids, (e.g. formic acid) have been accomplished. The results indicated that the aromatic carboxylic acids (benzoic acid and vanillic acid) are more stable than formic acid and acetic acid. Interestingly, the formic acid will even decompose to some other compounds at the very beginning of the in situ monitoring test. Further characterization found that water is one of the major products for the decomposition of formic acid in the 31 P NMR solution. Finally, as far as we know, this is the first report on such time-dependent changes when using 31 P NMR to analyze the pyrolysis oil, and these results show that proper application of this method is essential to achieve reliable quantitative data.
09 BIOMASS FUELS↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗