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Results for “PROPYLENE”

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.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Facile synthesis of epoxide-co-propylene sulphide polymers with compositional and architectural control

Here, we present a facile method to produce propylene sulphide (PS) homopolymers up to 100 kg mol -1 and PS-epoxide statistical, block, and ABA copolymers using inexpensive and versatile thio-aluminium (SAl) based initiators. Homopolymerizations of PS with SAl initiators are living and controlled, with number averaged molecular weights ($\bar M$ n ) up to 100 kg mol -1 while maintaining narrow polydispersity (Ð < 1.4). Statistical and block copolymers of PS and epichlorohydrin (ECH) or propylene oxide (PO) are synthesized and characterized by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), 1 H and 13 C NMR spectroscopy, diffusion ordered spectroscopy (DOSY), and small-angle X-ray scattering (SAXS). This work represents the first statistical copolymerization of PS and epoxides with similar reactivity ratios, allowing fine control over composition. Block-copolymers of PS and epoxides are synthesized by sequential addition, without intermediate preparative steps. Polymer architecture is controlled through modification of the initiator; we synthesized a di-functional (d-H) SAl initiator to produce ABA tri-block-copolymers. Finally, poly(ethylene glycol) (PEG) was used as a macroinitiator to create PEG-b-PPS block copolymers and characterized by 1 H, 13 C NMR spectroscopy, DOSY, DSC, and SEC.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Insights into the unique carboxylation reactions in the metabolism of propylene and acetone

Alkenes and ketones are two classes of ubiquitous, toxic organic compounds in natural environments produced in several biological and anthropogenic processes. In spite of their toxicity, these compounds are utilized as primary carbon and energy sources or are generated as intermediate metabolites in the metabolism of other compounds by many diverse bacteria. The aerobic metabolism of some of the smallest and most volatile of these compounds (propylene, acetone, isopropanol) involves novel carboxylation reactions resulting in a common product acetoacetate. Propylene is metabolized in a four-step pathway involving five enzymes where the penultimate step is a carboxylation reaction catalyzed by a unique disulfide oxidoreductase that couples reductive cleavage of a thioether linkage with carboxylation to produce acetoacetate. The carboxylation of isopropanol begins with conversion to acetone via an alcohol dehydrogenase. Acetone is converted to acetoacetate in a single step by an acetone carboxylase which couples the hydrolysis of MgATP to the activation of both acetone and bicarbonate, generating highly reactive intermediates that are condensed into acetoacetate at a Mn2+ containing the active site. Acetoacetate is then utilized in central metabolism where it is readily converted to acetyl-coenzyme A and subsequently converted into biomass or utilized in energy metabolism via the tricarboxylic acid cycle. This review summarizes recent structural and biochemical findings that have contributed significant insights into the mechanism of these two unique carboxylating enzymes.

Biochemistry & Molecular Biology↗
DOE OSTI2015

Effect of Fe{sub 3}O{sub 4} nanoparticles on space charge distribution in propylene carbonate under impulse voltage

Addition of nanoparticles of the ferromagnetic material Fe{sub 3}O{sub 4} can increase the positive impulse breakdown voltage of propylene carbonate by 11.65%. To further investigate the effect of ferromagnetic nanoparticles on the space charge distribution in the discharge process, the present work set up a Kerr electro-optic field mapping measurement system using an array photodetector to carry out time-continuous measurement of the electric field and space charge distribution in propylene carbonate before and after modification. Test results show that fast electrons can be captured by Fe{sub 3}O{sub 4} nanoparticles and converted into relatively slow, negatively charged particles, inhibiting the generation and transportation of the space charge, especially the negative space charge.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Direct propylene epoxidation via water activation over Pd-Pt electrocatalysts

Direct electrochemical propylene epoxidation by means of water-oxidation intermediates presents a sustainable alternative to existing routes that involve hazardous chlorine or peroxide reagents. Here, we report an oxidized palladium-platinum alloy catalyst (PdPtO x /C), which reaches a Faradaic efficiency of 66 ± 5% toward propylene epoxidation at 50 milliamperes per square centimeter at ambient temperature and pressure. Embedding platinum into the palladium oxide crystal structure stabilized oxidized platinum species, resulting in improved catalyst performance. The reaction kinetics suggest that epoxidation on PdPtO x /C proceeds through electrophilic attack by metal-bound peroxo intermediates. This work demonstrates an effective strategy for selective electrochemical oxygen-atom transfer from water, without mediators, for diverse oxygenation reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2010

Long Duration Life Test of Propylene Glycol Water Based Thermal Fluid Within Thermal Control Loop

Evaluations of thermal properties and resistance to microbial growth concluded that 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture was desirable for use as a fluid within a vehicle s thermal control loop. However, previous testing with a commercial mixture of PG and water containing phosphate corrosion inhibitors resulted in corrosion of aluminum within the test system and instability of the test fluid. This paper describes a follow-on long duration testing and analysis of 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture with inorganic corrosion inhibitors used in place of phosphates. The test evaluates the long-term fluid stability and resistance to microbial and chemical changes

Le, Hung↗
DOE OSTI2019

Selective oxidation of propane to propylene oxide

The invention provides a one pot method for generating propylene oxide, the method having the steps of contacting propane with catalyst clusters no greater than 30 atoms in the presence of oxygen for a time sufficient to directly convert the propane to the propylene oxide. The invented method eliminates the generation of intermediate compounds or intermediate reaction steps.

Vajda, Stefan↗
DOE OSTI2019

Promoter Effects on Catalyst Selectivity and Stability for Propylene Partial Oxidation to Acrolein

Herein, highly dispersed silica-supported CuO x /SiO 2 catalysts were synthesized via solution-phase deposition and studied for their activity, selectivity, and stability in catalyzing the selective oxidation of propylene to acrolein. Strategies for ensuring high metal dispersion included controlling the surface density of silanols (via covalent silanol-capping) or by pre-installing different "promoter" transition metals at submonolayer coverages. A comparison of the effect of first row transition metal promoters showed that V and Cr significantly boost catalyst performance and stabilize CuOx sites against aggregation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Effect of temperature and aging duration on ethylene propylene diene monomer (EPDM) nonmetallic components used in caustic liquid waste transfer lines

Nonmetallic materials are used in waste transfer lines at the United States Department of Energy’s Hanford Site Tank Farm in Benton County, Washington, USA. During use, the ethylene propylene diene monomer (EPDM) inner hose of the hose-in-hose transfer lines (HIHTLs) are exposed to β and γ radiation, caustic solutions as well as high temperatures and high pressures. Aging behavior of specimens of EPDM HIHTLs and dog-bone shaped specimens were evaluated by exposing to a solution of 25% sodium hydroxide (NaOH) at 38 °C, 54 °C and 77 °C for 6 and 12-months as well as water only at 77 °C for 12-months. Tensile strength and burst pressure of the specimens were characterized and compared with the unexposed (baseline) specimens. Both the tensile strength of the EPDM material and the burst pressure of the HIHTLs significantly decreased with the higher temperatures and longer exposure times. Analyses using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) of the HIHTLs and the dog-bone specimens were conducted. Our results show that the surface degradation increased with increasing exposure temperature. Penetration of NaOH into the EPDM material also increased with increasing temperature and exposure duration.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Effect of solution concentration on ethylene propylene diene monomer (EPDM) nonmetallic components used in caustic liquid waste transfer lines

The hose-in-hose transfer lines (HIHTL) used to transfer waste at the United States Department of Energy’s Hanford Site Tank Farm are fabricated from an ethylene propylene diene monomer (EPDM) synthetic rubber. During waste transport, these hoses are exposed to several stressors including caustic solutions at high temperatures and high pressures, as well as β and γ radiation. The aging behavior of HIHTL and dog-bone shaped EPDM specimens were evaluated by exposure to solutions at 77 °C containing 0.00, 6.25, 12.50, and 25.00 % (v/v) sodium hydroxide (NaOH) for 12-months. After the exposure, the material properties of the specimens were measured and compared to the unaged samples. The material properties evaluated included the tensile strength of the EPDM dog-bone samples and the burst pressure of the HIHTL. Both the tensile strength of the EPDM dog-bone samples and the burst pressure of the HIHTL specimens exposed to the 6.25 % NaOH solution exhibited the most significant deterioration and those exposed to 25.00 % NaOH solution had the least deterioration. Finally, examination of the HIHTL and the EPDM dog-bone specimens with scanning electron microscopy showed that the deterioration for the specimens exposed to 6.25 % NaOH solution were the most severe and the samples exposed to 25.00 % NaOH solution had the least deterioration.

42 ENGINEERING↗
DOE OSTI2012

Reproducible Preparation of Au/TS-1 with High Reaction Rate for Gas Phase Epoxidation of Propylene

A refined and reliable synthesis procedure for Au/TS-1(Si/Ti molar ratio {approx}100) with high reaction rate for the direct gas phase epoxidation of propylene has been developed by studying the effects of pH of the gold slurry solution, mixing time, and preparation temperature for deposition precipitation (DP) of Au on TS-1 supports. Au/TS-1 catalysts prepared at optimal DP conditions (pH {approx} 7.3, mixing for 9.5 h, room temperature) showed an average PO rate {approx} 160 g{sub PO} h{sup -1} kg{sub Cat}{sup -1} at 200 C at 1 atm. A reproducibility better than {+-}10% was demonstrated by nine independent samples prepared at the same conditions. These are the highest rates yet reported at 200 C. No visible gold particles were observed by the HRTEM analysis in the fresh Au/TS-1 with gold loading up to {approx}0.1 wt%, indicating that the gold species were smaller than 1 nm. Additionally, the rate per gram of Au and the catalyst stability increased as the Au loading decreased, giving a maximum value of 500 g{sub PO} h{sup -1} g{sub Au}{sup -1}, and Si/Ti molar ratios of {approx}100 gave the highest rates.

42 ENGINEERING↗
DOE OSTI2014

Combined Quantum Chemical/Raman Spectroscopic Analyses of Li+ Cation Solvation: Cyclic Carbonate Solvents - Ethylene Carbonate and Propylene Earbonate

Combined computational/Raman spectroscopic analyses of ethylene carbonate (EC) and propylene carbonate (PC) solvation interactions with lithium salts are reported. It is proposed that previously reported Raman analyses of (EC)n-LiX mixtures have utilized faulty assumptions. In the present studies, density functional theory (DFT) calculations have provided corrections in terms of both the scaling factors for the solvent's Raman band intensity variations and information about band overlap. By accounting for these factors, the solvation numbers obtained from two different EC solvent bands are in excellent agreement with one another. The same analysis for PC, however, was found to be quite challenging. Commercially available PC is a racemic mixture of (S)- and (R)-PC isomers. Based upon the quantum chemistry calculations, each of these solvent isomers may exist as multiple conformers due to a low energy barrier for ring inversion, making deconvolution of the Raman bands daunting and inherently prone to significant error. Thus, Raman spectroscopy is able to accurately determine the extent of the EC...Li+ cation solvation interactions using the provided methodology, but a similar analysis of PC...Li+ cation solvation results in a significant underestimation of the actual solvation numbers.

CARBONIC ACID ESTERS↗
DOE OSTI2024

Support size regulated ruthenium-sulfoacid-nitrogen sites intensify cellulose hydrogenolysis to 1,2-propylene glycol

Rational design of metal-acid-base multifunctional catalysts for upgrading cellulose to 1,2-propylene glycol (1,2-PG) is of great significance for building a sustainable world. However, it is time-consuming and tedious to regulate metal-acid-base sites to balance major reactions to render a high 1,2-PG yield. We herein report support size simultaneously regulated ruthenium-sulfoacid-nitrogen (Ru–SO 3 H–N) sites for cellulose hydrogenolysis to high yield 1,2-PG. Originated from the depolymerization and reassembly of zinc-1,3,5-benzenetricarboxylic acid (ZnBTC) fiber with zeolitic imidazolate framework (ZIF-8) in water, 2-methylimidazole infiltrated nanorod (ZnBTC(mIM)) with a varied aspect ratio was fabricated by varying the feed ratio of ZIF-8/ZnBTC. Upon being pyrolyzed, sulfonated and impregnated with Ru ions, the supported sites were tailored in terms of Ru single-atom/nanocluster ratio, SO 3 H acidity and N basicity. Further, the elaborately fabricated catalyst delivers 32.3% yield of 1,2-PG, corresponding to a high productivity of 67.71 mol h -1 g Ru -1 and a large turnover number of 34193, two and three orders of magnitude higher than those by using other Ru-containing catalytic systems for cellulose hydrogenolysis. The excellent performance can be attributed to optimized electronic and molecular structure of Ru–SO 3 H–N sites that can improve rate-determining cellulose hydrolysis/fructose hydrogenolysis, pivotal glucose isomerization with others to proceed at a matched rate. This study opens a new avenue to facilely tailor the metal-acid-base sites by rational design of size controlled supporting matrix.

1,2-Propylene glycol↗
DOE OSTI2022

Infrared Spectroscopy of Li + Solvation in EmimBF 4 and in Propylene Carbonate: Ab Initio Molecular Dynamics and Experiment

Infrared (IR) spectra of solutions of the lithium salt LiBF 4 in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF 4 ) and in the organic solvent propylene carbonate (PC) are studied via infrared spectroscopy and ab initio molecular dynamics (AIMD) simulations. The measurements show that the major effects of LiBF 4 in both solutions, compared to their neat counterparts, are the appearance of a new broad band in the 300-450 cm -1 frequency region and a broadening of the IR structure in the 900-1200 cm -1 region with the development of a new peak at 980 cm -1 . Computational analysis indicates that hindered translational motions of Li + in its solvation cage are mainly responsible for the former, while the latter is due to Li + -induced structural changes and accompanying vibrational frequency shifts of constituent ions and molecules of the solutions. In addition, molecular motions in these and lower frequency regions are generally correlated, disclosing the collective nature of the vibrational dynamics, which involve multiple ions/molecules. Herein, detailed analysis of these features via AIMD simulations of the spectrum and its components arising from auto- and cross-correlations of motions of constituent molecular species, combined with generalized normal modes of the solutions and normal modes of small Li + -containing clusters, is presented. Furthermore, other minor spectral changes caused by the lithium salt as well as the interaction-induced effect on IR spectra are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Doubly Interpenetrated Metal-Organic Framework of pcu Topology for Selective Separation of Propylene from Propane

We report that adsorptive separation is an appealing alternative technology to reduce the high energy and capital cost of the distillation separation of propylene/propane; however, it is very challenging to realize. A new flexible metal-organic framework (MOF) material [Zn 2 (BDC-Cl) 2 (Py 2 TTz)] with a doubly interpenetrated pillared paddle wheel structure of pcu (primitive cubic) topology has been realized for this difficult separation for the first time. Through a judicious choice of linkers, the framework has small pore apertures that lead to much more propylene adsorption than propane. The selective adsorption relies on the sieving effect of the flexible framework. The column breakthrough experiment further demonstrated that efficient separation can be achieved under dynamic conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Superhydrophobicity on transparent fluorinated ethylene propylene films with nano-protrusion morphology by Ar + O{sub 2} plasma etching: Study of the degradation in hydrophobicity after exposure to the environment

Fluorinated ethylene propylene (FEP) films were made superhydrophobic by Ar + O{sub 2} plasma etching process. Field emission scanning electron microscopy and atomic force microscopy studies of the plasma-treated FEP samples detected the presence of uniformly distributed nano-protrusions exhibiting a low surface roughness necessary for maintaining the transparency of the samples. In fact, optical transmittance measurements showed an improvement in the transparency of FEP samples after plasma treatment. The X-ray photoelectron spectroscopic analysis showed the presence of –CF{sub x}–O–CF{sub x}– (x = 1, 2, or 3) linkages in both untreated and plasma-treated samples which explains the hydrophilic nature (contact angle below 90{sup ∘}) of the untreated sample. Fourier transform infrared spectroscopy showed no changes in the bulk properties of the plasma-treated samples. Moreover, exposure to the environment caused the surfaces to lose their superhydrophobic property in an indefinite amount of time. This has been further studied through a water immersion experiment and explained through the wetting state transition from Cassie state to Wenzel state.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering

The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H{sub 2}O (or D{sub 2}O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0–90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the corresponding bulk system, showing the important role of hydrogen bonding for the dynamics. In this study we have elucidated how this non-monotonic concentration dependence is affected by the confined geometry. The results show that this behaviour is maintained in the confinement, but the slowest diffusive dynamics of 2PGME is now observed at a considerably higher water concentration; at 75 wt.% water in MCM-41 compared to 30 wt.% water in the corresponding bulk system. This difference can be explained by an improper mixing of the two confined liquids. The results suggest that water up to a concentration of about 20 wt.% is used to hydrate the hydrophilic hydroxyl surface groups of the silica pores, and that it is only at higher water contents the water becomes partly mixed with 2PGME. Hence, due to this partial micro-phase separation of the two liquids larger, and thereby slower relaxing, structural entities of hydrogen bonded water and 2PGME molecules can only be formed at higher water contents than in the bulk system. However, the Q-dependence is unchanged with confinement, showing that the nature of the molecular motions is preserved. Thus, there is no indication of localization of the dynamics at length scales of less than 20 Å. The dynamics of both water and 2PGME is strongly dominated by translational diffusion at a temperature of 280 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Synthesis and the crystal and molecular structure of the germanium(IV) complex with propylene-1,3-diaminetetraacetic acid [Ge(Pdta)]

The germanium(IV) complex with propylene-1,3-diaminetetraacetic acid (H{sub 4}Pdta) is studied by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. The X-ray diffraction study reveals two crystallographically independent [Ge(Pdta)] molecules of similar structure. Both Ge atoms are octahedrally coordinated by four O atoms and two N atoms (at the cis positions) of the hexadentate pentachelate Pdta{sup 4–} ligand. An extended system of weak C—H···O hydrogen bonds connects complex molecules into a supramolecular 3D framework.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗