Direct Catalytic Conversion of Ethanol to C[subscript 5+] Ketones: Role of Pd-Zn Alloy on Catalytic Activity and Stability
Abstract not provided
Subramaniam, Senthil↗
SEARCH · Search NASA
Results for “ketones”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Engineering β-oxidation in Yarrowia lipolytica for methyl ketone production
Not Available
Hanko, Erik K. R.↗
Enhanced Hydrothermal Stability and Catalytic Activity of LaxZryOz Mixed Oxides for the Ketonization of Acetic Acid in the Aqueous Condensed Phase
Common ketonization catalysts such as ZrO2, CeO2, and TiO2-based catalysts have been reported to lose surface area, undergo phase transformation, and lose catalytic activity when utilized in the condensed aqueous phase. In this work, we synthesized a series of LaxZryOz mixed-metal oxides with different La:Zr atomic ratios with the goal of enhancing the catalytic activity and stability for the ketonization of acetic acid in condensed aqueous media at 568 K. We synthesized a hydrothermally stable LaxZryOz mixed-metal oxide catalyst with ketonization activity360 and 40 times more active than La2O3 and ZrO2, respectively. Catalyst characterization techniques suggest that the enhanced stability of the LaxZryOz catalysts is observed with the formation of a phase isomorphic with tetragonal ZrO2. DRIFT spectroscopy measurements indicated the enhanced catalytic activity of LaxZryOz catalysts correlated with greater acetic acid surface population in the presence of H2O versus pure ZrO2.
ketonization, deoxygenation, carboxylic acid, acet↗
Photolysis of Tp'Rh(CNneopentyl)(PhNCNneopentyl) in the presence of ketones and esters: kinetic and thermodynamic selectivity for activation of different aliphatic C–H bonds
The competitive fragment [Tp'Rh(CNneopentyl)], generated from the precursor Tp'Rh(CNneopentyl)(PhN CNneopentyl), underwent oxidative addition of substituted ketones and esters resulting in Tp'Rh(CNneopentyl)(R)(H) complexes (Tp' = tris-(3,5-dimethylpyrazolyl)borate). These C–H activated complexes underwent reductive elimination at varying temperatures (24–70 °C) in C 6 D 6 or C 6 D 12 . Using previously established kinetic techniques, the relative Rh–C bond strengths were calculated. Analysis of the relative Rh–C bond strengths vs. C–H bond strengths demonstrates a linear correlation with slope R M–C/C–H = 1.22 (12). In general, α-substituents increase the relative Rh–C bond strengths compared to the C–H bond that is broken.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Redox-active on-surface polymerization of single-site divalent cations from pure metals by a ketone-functionalized phenanthroline
Metallic iron, chromium, or platinum mixing with a ketone-functionalized phenanthroline ligand on a single crystal gold surface demonstrates redox activity to a well-defined oxidation state and assembly into thermally stable, one dimensional, polymeric chains. The diverging ligand geometry incorporates redox-active sub-units and bi-dentate binding sites. The gold surface provides a stable adsorption environment and directs growth of the polymeric chains, but is inert with regard to the redox chemistry. These systems are characterized by scanning tunnelling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy under ultra-high vacuum conditions. The relative propensity of the metals to interact with the ketone group is examined, and it is found that Fe and Cr more readily complex the ligand than Pt. The formation and stabilization of well-defined transition metal single-sites at surfaces may open new routes to achieve higher selectivity in heterogeneous catalysts.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Rheological behavior of neat and carbon fiber-reinforced poly(ether ketone ketone) for extrusion deposition additive manufacturing
To develop new materials for extrusion additive manufacturing (AM) systems, a fundamental understanding of rheological properties is essential to correlate the effect of processing on material structure and its properties. In this work, the rheological properties of five different grades of neat and carbon fiber (CF)-reinforced poly(ether ketone ketone) are reported. Rheological properties are essential to understand the effect of reinforcing fibers and AM process parameters such as time, temperature, environment, and shear rate on flow behavior during processing. Small-amplitude oscillatory shear tests and steady shear tests indicated neat grades to exhibit less increase in viscosity over time when processed in air than the CF-filled grades. The filled grades showed greater shear thinning and lower sensitivity to temperature. Altogether, this rheological analysis provides a broad framework for determining appropriate processing conditions for extrusion deposition AM of such high-temperature polymer systems.
36 MATERIALS SCIENCE↗
Resonance stabilization effects on ketone autoxidation: Isomer-specific cyclic ether and ketohydroperoxide formation in the low-temperature (400–625 K) oxidation of diethyl ketone
Here, the pulsed photolytic chlorine-initiated oxidation of diethyl ketone [DEK; (CH 3 CH 2 ) 2 C=O], 2,2,4,4- d 4 -DEK [ d 4 -DEK; (CH 3 CD 2 ) 2 C=O], and 1,1,1,5,5,5-d 6 -DEK [ d 6 -DEK; (CD 3 CH 2 ) 2 C=O] is studied at 8 torr and 1–2 atm and from 400–625 K. Cl atoms produced by laser photolysis react with diethyl ketone to form either primary (3-pentan-on-1-yl, R P ) or secondary (3-pentan-on-2-yl, R S ) radicals, which in turn react with O 2 . Multiplexed time-of-flight mass spectrometry, coupled to either a hydrogen discharge lamp or tunable synchrotron photoionizing radiation, is used to detect products as a function of mass, time, and photon energy. At 8 torr, the nature of the chain propagating cyclic ether + OH channel changes as a function of temperature. At 450 K, the production of OH is mainly in conjunction with formation of 2,4-dimethyloxetan-3-one, resulting from reaction of the resonance-stabilized secondary R S with O 2 . In contrast, at 550 K and 8 torr, 2-methyl-tetrahydrofuran-3-one, originating from oxidation of the primary radical (RP), is observed as the dominant cyclic ether product. Formation of both of these cyclic ether production channels proceeds via a resonance-stabilized hydroperoxy alkyl (QOOH) intermediate. Little or no ketohydroperoxide (KHP) is observed under the low-pressure conditions. At higher O 2 concentrations and higher pressures (1–2 atm), a strong KHP signal appears as the temperature is increased above 450 K. Definitive isomeric identification from measurements on the deuterated DEK isotopologues indicates the favored pathway produces a γ-KHP via resonance-stabilized alkyl, QOOH, and HOOPOOH radicals. Time-resolved measurements reveal the KHP formation becomes faster and signal more intense upon increasing temperature from 450 to 575 K before intensity drops significantly at 625 K. The KHP time profile also shows a peak followed by a gradual depletion for the extent of experiment. Several tertiary products exhibit a slow accumulation in coincidence with the observed KHP decay. These products can be associated with decomposition of KHP by β-scission pathways or via isomerization of a γ-KHP into a cyclic peroxide intermediate (Korcek mechanism). The oxidation of d 4 -DEK, where kinetic isotope effects disfavor γ-KHP formation, shows greatly reduced KHP formation and associated signatures from KHP decomposition products.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Four-Carbon Criegee Intermediate from Isoprene Ozonolysis: Methyl Vinyl Ketone Oxide Synthesis, Infrared Spectrum, and OH Production
The reaction of ozone with isoprene, one of the most abundant volatile organic compounds in the atmosphere, produces three distinct carbonyl oxide species (RR'COO) known as Criegee intermediates: formaldehyde oxide (CH 2 OO), methyl vinyl ketone oxide (MVK-OO), and methacrolein oxide (MACR-OO). The nature of the substituents (R,R' = H, CH 3 , CH＝CH 2 ) and conformations of the Criegee intermediates control their subsequent chemistry in the atmosphere. In particular, unimolecular decay of MVK-OO is predicted to be the major source of hydroxyl radicals (OH) in isoprene ozonolysis. Our study reports the initial laboratory synthesis and direct detection of MVK-OO through reaction of a photolytically generated, resonance-stabilized monoiodoalkene radical with O 2 . MVK-OO is characterized utilizing infrared (IR) action spectroscopy, in which IR activation of MVK-OO with two quanta of CH stretch at ca. 6000 cm –1 is coupled with ultraviolet detection of the resultant OH products. MVK-OO is identified by comparison of the experimentally observed IR spectral features with theoretically predicted IR absorption spectra. For syn -MVK-OO, the rate of appearance of OH products agrees with the unimolecular decay rate predicted using statistical theory with tunneling. This validates the hydrogen atom transfer mechanism and computed transition-state barrier (18.0 kcal mol –1 ) leading to OH products. Theoretical calculations display a further roaming pathway between the separating radical fragments, which results in other products. Master equation modeling yields a thermal unimolecular decay rate for syn -MVK-OO of 33 s –1 (298 K, 1 atm). For anti -MVK-OO, theoretical exploration of several unimolecular decay pathways predicts that isomerization to dioxole is the most likely initial step to products.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Data for Rewiring Yeast Metabolism for Producing 2,3-Butanediol and Two Downstream Applications: Techno-Economic Analysis and Life Cycle Assessment of Methyl Ethyl Ketone (MEK) and Agricultural Biostimulant Production
Rising concerns for sustainability and global climate change have driven the development of sustainable production pathways for biofuels and chemicals from lignocellulosic biomass via integrated biological and chemical processes. We constructed an engineered Saccharomyces cerevisiae capable of producing 2,3-butanediol (2,3-BDO) from glucose without accumulating ethanol and glycerol, which hinder downstream processing of 2,3-BDO, through extensive metabolic reprogramming. Specifically, we introduced heterologous 2,3-BDO biosynthetic enzymes and deleted the major isozymes of ethanol and glycerol biosynthetic enzymes. In addition, we introduced an NAD+ regenerating Pyruvate-Malate (PM) cycle and enhanced the NAD+ regenerating capability of the PM cycle to resolve the redox imbalance from the deletion of ethanol and glycerol production pathways. The resulting engineered yeast produced 109.9 g/L of 2,3-BDO with a productivity of 1.0 g/L/h and a yield of 0.36 g/g glucose in a fed-batch fermentation. We also conducted techno-economic analysis (TEA) and life cycle assessment (LCA) of the production of methyl ethyl ketone (MEK) through catalytic dehydration of 2,3-BDO. A TEA based on the experimental results indicated that the minimum product selling price (MPSP) was estimated to be $1.90/kg. Regarding cradle-to-grave LCA, 100-year global warming potential (GWP100) and fossil energy consumption (FEC) were found to be 0.37 kg CO2 eq/kg and 3.1 MJ/kg, respectively. These results demonstrated the feasibility of cost-competitive and sustainable bio-based MEK production via yeast fermentation. In addition, we explored the possibility of using the fermentation broth containing 2,3-BDO as a biostimulant inducing drought tolerance in plants. As a result, the yeast 2,3-BDO fermentation broth can induce drought tolerance in Arabidopsis thaliana without a complicated purification process.
Economics↗
Study of Poly(ether ketone ketone) (PEKK): Outgassing Characteristics and Likely Residual Synthesis Impurities
In May-June, 2020, a study was conducted to characterize the outgassing properties of a series PEKK (Poly(ether ketone ketone)) samples using cryo-GC/MS headspace analysis. Three sets of samples were interrogated: sample group 1 consisted of 2 additively manufactured PEKK samples (PEKK "ole and "New") prepared by KCNSC from powder material from Solvay Specialty Polymers USA, LLC. Sample groups 2 and 3 consist of 5 PEKK powder types (used as feedstock for additive manufacturing processes) and 4 additively-manufactured PEKK material lots, respectively. Contrary to expectations, all samples of PEKK material were observed to outgas sulfur-containing compounds. Other analyses (EDS/EMA, GC-TOF/MS of PEKK sample extractions) confirmed the presence of sulfur in the PEKK bulk material. Specifically, Diphenyl sulfone (used as a reagent or high-temperature solvent in the synthesis of Polyaryletherketone or PAEK polymers) was observed in three of the powders and in both the PEKK "Old" and "New" samples, suggesting that the source of the sulfur can be traced to impurities in the material left over from the synthesis process.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Rheological Characteristics of Fiber Reinforced Poly(Ether Ketone Ketone) (PEKK) for Melt Extrusion Additive Manufacturing
Several grades of unreinforced and short fiber reinforced poly(ether ketone ketone) (PEKK) copolymers are analyzed for their potential use as feedstock materials in melt extrusion-based additive manufacturing (AM) systems. Rheological characterization has been performed to study the effect of extrusion processing parameters such as time, temperature, environment, and shear rate for the selected materials. The effect of reinforcing filler content on the melt processing conditions of PEKK composites are also reported, and processing conditions for successful extrusion of these materials on AM systems are determined.
Kishore, Vidya↗
Pt/Ferric Hydroxyphosphate: An Effective Catalyst for the Selective Hydrogenation of α,β-Unsaturated Aldehydes (Ketones) into α,β-Unsaturated Alcohols
Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5–4.6 nm. When the four different Pt/FHP catalysts were used into the hydrogenation of α,β-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested α,β-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Structure and proton conduction in sulfonated poly(ether ether ketone) semi-permeable membranes: a multi-scale computational approach.
The design of polymeric membranes for proton or ionic exchange highly depends on the fundamental understanding of the physical and molecular mechanisms that control the formation of the conduction channels. There is an inherent relation between the dynamical structure of the polymeric membrane and the electrostatic forces that drive membrane segregation and proton transport. Here, we used a multi-scale computational approach to analyze the morphology of sulfonated poly(ether ether ketone) membranes at the mesoscale. A self-consistent description of the electrostatic phenomenon was adopted, where discrete polymer chains and a continuum proton field were embedded in a continuum fluid. Brownian dynamics was used for the evolution of the suspended polymer molecules, while a convection-diffusion transport equation, including the Nernst-Planck diffusion mechanism, accounted for the dynamics of the proton concentration field. We varied the polymer concentration, the degree of sulfonation and the level of confinement to find relationships between membrane structure and proton conduction. Our results indicate that the reduced mobility of polymer chains, at concentrations above overlap, and a moderate degree of sulfonation -i.e., 30% - are essential elements for membrane segregation and proton domain connectivity. These conditions also ensure that the membrane structure is not affected by size or by potential gradients. Importantly, our analysis shows that membrane conductivity and current are linearly dependent on polymer concentration and quadratically dependent on the degree of sulfonation. We found that the optimal polymeric membrane design requires a polymer concentration above overlap and a degree of sulfonation around 50%. These conditions promote a dynamical membrane morphology with a constant density of proton channels. Our results and measurements agree with previous experimental works, thereby validating our model and observations.
Molina, Jarol↗
Kinetics and Reactor Modeling of VFA Ketonization for Sustainable Aviation Fuel Production
Ketonization of volatile fatty acids (VFAs) produced via arrested methanogenesis of wet waste represents the only unit operation of wet waste upgrading to sustainable (net-zero or negative life cycle CO2 emissions) aviation fuel not currently in industrial practice. Ketone product yields of close to 100% have been obtained during gas-phase reactions of VFAs over oxide catalysts at the laboratory scale, but design of an industrial ketonization reactor requires understanding of the impacts of reactant and product partial pressures, deactivation, and heat and mass transport phenomena on observed ketonization rates. Our work leverages rigorous kinetic analysis of ketonization processes to inform reactor scale-up efforts through packed-bed reactor modeling. We first present results of a kinetic study of ketonization of a model VFA, hexanoic acid, over an industrial ZrO2 catalyst performed in a packed-bed microreactor in conditions free of significant heat or mass transfer gradients. Major findings of the analysis include: (i) hexanoic acid saturates all catalyst active sites at relatively low partial pressure (~10 kPa) and (ii) ketonization products 6-undecanone, water, and CO2 inhibit reaction rates. Kinetic data are used to fit a rate expression quantifying the functional dependence of ketonization rate on partial pressures of VFA reactants and ketone, water, and CO2 products. A packed-bed reactor model describing vapor-phase hexanoic acid ketonization over ZrO2 extrudate catalysts is developed based on the kinetic model. The effects of (i) bed- and pellet-scale mass- and heat-transfer limitations and (ii) axial pressure drop guide our development of recommendations for optimal sizing, temperature, and influent flow composition of an industrial-scale ketonization reactor. The quantitative understanding of VFA ketonization developed in this study represents an advance toward derisking the VFA ketonization step of wet waste upgrading to sustainable aviation fuel.
biojet↗
Detection of Ketones by a Novel Technology: Dipolar Proton Transfer Reaction Mass Spectrometry (DP-PTR-MS)
Proton transfer reaction mass spectrometry (PTR-MS) has played an important role in the field of real-time monitoring of trace volatile organic compounds (VOCs) due to its advantages such as low limit of detection (LOD) and fast time response. Recently, a new technology of proton extraction reaction mass spectrometry (PER-MS) with negative ions OH{sup –} as the reagent ions has also been presented, which can be applied to the detection of VOCs and even inorganic compounds. In this work, we combined the functions of PTR-MS and PER-MS in one instrument, thereby developing a novel technology called dipolar proton transfer reaction mass spectrometry (DP-PTR-MS). The selection of PTR-MS mode and PER-MS mode was achieved in DP-PTR-MS using only water vapor in the ion source and switching the polarity. In this experiment, ketones (denoted by M) were selected as analytes. The ketone (molecular weight denoted by m) was ionized as protonated ketone [M + H]{sup +} [mass-to-charge ratio (m/z) m + 1] in PTR-MS mode and deprotonated ketone [M – H]{sup –} (m/z m – 1) in PER-MS mode. By comparing the m/z value of the product ions in the two modes, the molecular weight of the ketone can be positively identified as m. Results showed that whether it is a single ketone sample or a mixed sample of eight kinds of ketones, the molecular weights can be detected with DP-PTR-MS. The newly developed DP-PTR-MS not only maintains the original advantages of PTR-MS and PER-MS in sensitive and rapid detection of ketones, but also can estimate molecular weight of ketones. .
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Experimental and Computational Studies of Carbon–Carbon Bond Formation via Ketonization and Aldol Condensation over Site-Isolated Zirconium Catalysts
We report here the preparation and investigation of isolated Zr centers supported on a high surface area silica for the conversion of carboxylic acids to internal ketones by ketonic decarboxylation (ketonization) and the aldol condensation of ketones to dimeric enones. Catalysts were synthesized by the grafting of Cp 2 ZrCl 2 on the surface of amorphous silica. The connectivity of Zr was characterized by XRD, UV-vis, and Raman spectroscopy. For the lowest Zr loading, Zr is present predominantly as isolated monomeric species. As the Zr loading is increased, a progressively larger fraction of Zr forms oligomeric species and ZrO nanoparticles. Measurements of catalytic activity show that the turnover frequency for carboxylic acid ketonic decarboxylation reaction and aldol condensation of ketones decreases monotonically with increasing Zr loading. An H/D kinetic isotope effect was not observed over isolated Zr catalysts, suggesting that α-H abstraction is not the rate-determining step, rather C-C bond forming may be rate limiting for both reactions. This conclusion is supported by computational modeling of the reaction mechanism. The proposed catalytic cycle for ketonization proceeds via a β-keto acid intermediate on isolated Zr sites that are always coordinatively saturated with C-C bond formation as the rate-limiting step. C-C bond formation is also rate-determining for aldol condensation, with an apparent activation energy that is in good agreement with the experiment if the resting state is a saturated ≡ZrOH site with two adsorbed ketone molecules.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗