Search NASA⌕ Search

SEARCH · Search NASA

Results for “propane”

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.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

New Insights into Low-Temperature Oxidation of Propane from Synchrotron Photoionization Mass Spectrometry and Multiscale Informatics Modeling

We investigated the low-temperature oxidation of propane at 4 Torr and temperatures of 530, 600, and 670 K. The oxidation is initiated by pulsed laser photolysis of oxalyl chloride, (COCl)2, at 248 nm, which rapidly generates a ~1:1 mixture of 1-propyl (n-propyl) and 2-propyl (i-propyl) radicals via the fast Cl + propane reaction. Reactants, intermediates and products are probed with isomeric selectivity by time-resolved multiplexed photoionization mass spectrometry (MPIMS) with tunable synchrotron vacuum UV radiation as the ionization source. At all three temperatures, the major stable product species is propene, formed in the C3H7 + O2 reactions by direct HO2-elimination from both n- and i-propyl peroxy radicals. The experimentally derived propene yields relative to the initial concentration of Cl atoms are (20 ± 4)% at 530 K, (55 ± 11)% at 600 K, and (86 ± 17)% at 670 K at a reaction time of 20 ms. The lower yield of propene at low temperature reflects substantial formation of propyl peroxy radicals, which do not completely decompose on the experimental time scale. In addition, we detect the C3H6O isomers methyloxirane, oxetane, acetone and propanal as minor products. Our measured yields of oxetane and methyloxirane, which are co-products of OH radicals, suggest a revision of the OH formation pathways in models of low-temperature propane oxidation. The experimental results are modeled and interpreted using a multi-scale informatics approach that is presented in detail in a separate publication (Burke, M. P.; Goldsmith, C. F.; Klippenstein, S. J.; Welz, O.; Huang H.; Antonov I. O.; Savee J. D.; Osborn D. L.; Zádor, J.; Taatjes, C. A.; Sheps, L., Multi-Scale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Rections, submitted, 2015). The model predicts the time profiles and yields of the experimentally observed primary products well, and shows satisfactory agreement for products formed mostly via secondary radical-radical reactions.

Combustion↗
DOE OSTI2018

Hexagonal boron nitride catalyst in a fixed-bed reactor for exothermic propane oxidation dehydrogenation

Hexagonal boron nitride (h-BN) with high thermal conductivity is potentially an effective catalyst for highly exothermic propane oxidative dehydrogenation (ODH) reaction. Here, we report our experimental and theoretic studies of such a catalyst for propane ODH in a fixed-bed reactor. Based on the computational fluid dynamics calculation (CFD) results, the catalyst bed temperature increases by less than 1 degrees C in the h-BN catalyst bed which is much smaller than that (8 degrees C) in the VOx/gamma-Al2O3 catalyst bed at a similar propane conversion (25%) using a micro-tubular reactor with a diameter of 6 mm. Even in an industrially relevant reactor with an inner diameter of 60 mm, a uniform temperature profile can still be maintained using the h-BN catalyst bed due to its excellent thermal conductivity as opposed to a temperature gradient of 47 degrees C in the VOx/gamma-Al2O3 catalyst bed. The results reported here provide useful information for potential application of h-BN catalyst in propane ODH. (C) 2018 Elsevier Ltd. All rights reserved.

Tian, jinshu↗
DOE OSTI2019

Propane Liquefaction with an Active Magnetic Regenerative Liquefier

Magnetic refrigeration is a cooling technique that uses the magnetocaloric e?ect (MCE). The active magnetic regenerator (AMR) cycle is a regenerative cycle that employs the MCE and consists of four steps: adiabatic magnetization with no heat transfer gas flow; heat transfer gas flow at constant high field; demagnetization with no heat transfer gas flow; and heat transfer gas flow at constant low field. The first heat transfer gas cold-to-hot flow step rejects heat from the magnetized regenerator to a hot sink and the second reverse heat transfer gas hot-to-cold flow step add heat from a cold source into the demagnetized regenerator. Our primary research and development objective is to use the MCE for more efficient liquefaction of much colder cryogens, to help identify problems of effective coupling of cold heat transfer gas of a single-stage reciprocating magnetic refrigerator to a process gas, we have used a single-stage active magnetic regenerative refrigerator (AMRR) with Gd refrigerant to liquefy pure propane gas at two different supply pressures. The high-purity propane was supplied from a small regulated lecture bottle at 295 K via a 1.6 mm o.d. stainless-steel tube into the helium-cooled coiled-fin tube heat exchanger at 49 psia or 27 psia, to liquefy propane at 262 K or 246 K, respectively. Propane liquefied until the small collection vessel and the coiled fin tube heat exchanger were filled at which the flow from the open lecture bottle stopped. The measured rate of liquefaction and the elapsed time for each case were measured and used to determine the volume of propane collected and the cooling power of the AMRR at the liquefaction temperatures. These cooling power results were compared to the cooling power results obtained from the curve of cool-down temperature vs. time data and agreement was excellent after the duty cycle of each cooling process was properly treated.

propane, liquefaction, active magnetic regenerator↗
DOE OSTI2025

Stable isotope equilibria in the dihydrogen-water-methane-ethane-propane system. Part 2: Experimental determination of hydrogen isotopic equilibrium for ethane-H2 from 30 to 200 °C and propane-H2 from 75 to 200 °C

The stable isotopic compositions of light n-alkanes, including methane, ethane, and propane, are often used to identify the sources and thermal maturity of natural gas samples. Though stable isotopic compositions of these molecules are commonly assumed to be controlled by kinetic isotope effects, recent studies have proposed both carbon and hydrogen isotopic equilibrium may also occur in some samples. Assessing whether samples are in isotopic equilibrium requires knowledge of light alkane equilibrium fractionation factors over geologically relevant temperatures for formation and storage (up to ∼300 °C). In this study, we report experimental results of hydrogen isotopic equilibrium between ethane and H2 from 30 to 200 °C and propane and H2 from 75 to 200 °C. We compare these results with high-level theoretical calculations and provide a preferred polynomial fit to describe equilibrium fractionation factors. Comparison of these fractionation factors with a compilation of ∼500 compiled environmental gas samples supports the proposal that many (∼50%) of these natural gas samples exhibit hydrogen isotopic compositions consistent with having formed in or attained methane-ethane-propane hydrogen isotopic equilibrium over geologically relevant temperatures for formation and storage (50–300 °C).

Turner, Andrew C↗
DOE OSTI2021

Understanding the Correlation between Ga Speciation and Propane Dehydrogenation Activity on Ga/H-ZSM-5 Catalysts

H-ZSM-5 zeolite-supported Ga (Ga/H-ZSM-5) has been considered as a selective catalyst for nonoxidative propane dehydrogenation (PDH) for decades; however, the reaction mechanism remains a topic of considerable discussion. In particular, the correlation between various Ga species present on the catalyst at the reaction conditions and the PDH activity has yet to be established. In this work, intrinsic PDH rates and activation energies were determined on Ga + –H + pair sites and isolated Ga + sites on Ga/H-ZSM-5 samples with a wide range of Si/Al and Ga/Al ratios. Here, the turnover frequency on Ga + –H + pair sites in the PDH is higher than that of isolated Ga + sites by a factor of ~15. Experimental measurements combined with a dual-site model show the activation energy in the PDH on the Ga + –H + pair sites and isolated Ga + sites to be 90.8 ± 1.5 and 117 ± 4.7 kJ·mol –1 , respectively. These results demonstrate that Ga+–H+ pair sites are much more active in the PDH than isolated Ga + sites. The activation energy of GaH x decomposition to form H 2 was determined to be 40–60 kJ·mol –1 higher than that of the PDH on Ga species, suggesting that the GaH x decomposition is unlikely to be part of the PDH mechanism. Although both Brønsted acid and Ga sites interact with propane, Fourier transform infrared spectroscopy results provide strong evidence suggesting that the alkyl mechanism is more likely in the PDH on Ga/H-ZSM-5 catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Process Intensification of Distillation using a Microwick Technology to Demonstrate Separation of Propane and Propylene

Process intensification (PI) of distillation using a microchannel distillation (MCD) device successfully reduced the height of a theoretical plate (HETP) in separating propane and propylene to 1 cm, representing 10 theoretical stages. Mass transfer is enhanced by using thin wicking structures that are 0.17 mm thick in counter-flow with vapor. Liquid is segregated in the wicks by applying a siphon, which also enables the device to operate horizontally. A scalable device containing 11 wicks was operated cryogenically in total reflux. The HETP varied between 1.0 and 3.7 cm, representing a dramatic reduction over commercial structured packings and comparable to other PI approaches. Significant improvements are expected with further development. Potential application for intensified distillation processes include distributed manufacturing and difficult separations involving close boiling compounds and meeting high purity specifications. The ultimate application is isotopic enrichment, where the number of stages required is typically multiple thousands.

Distillation, Process Intensification, Microchanne↗
DOE OSTI2017

Thermally Stable and Regenerable Platinum–Tin Clusters for Propane Dehydrogenation Prepared by Atom Trapping on Ceria

Abstract Ceria (CeO 2 ) supports are unique in their ability to trap ionic platinum (Pt), providing exceptional stability for isolated single atoms of Pt. The reactivity and stability of single‐atom Pt species was explored for the industrially important light alkane dehydrogenation reaction. The single‐atom Pt/CeO 2 catalysts are stable during propane dehydrogenation, but are not selective for propylene. DFT calculations show strong adsorption of the olefin produced, leading to further unwanted reactions. In contrast, when tin (Sn) is added to CeO 2 , the single‐atom Pt catalyst undergoes an activation phase where it transforms into Pt–Sn clusters under reaction conditions. Formation of small Pt–Sn clusters allows the catalyst to achieve high selectivity towards propylene because of facile desorption of the product. The CeO 2 ‐supported Pt–Sn clusters are very stable, even during extended reaction at 680 °C. Coke formation is almost completely suppressed by adding water vapor to the feed. Furthermore, upon oxidation the Pt–Sn clusters readily revert to the atomically dispersed species on CeO 2 , making Pt–Sn/CeO 2 a fully regenerable catalyst.

Xiong, Haifeng↗
DOE OSTI2015

Selective propane dehydrogenation with single-site Co II on SiO 2 by a non-redox mechanism

We report the synthesis, characterization, and catalytic performance for gas phase propane dehydrogenation of single-site Co2+ ions supported on silica. Spectroscopic characterization by resonance Raman, electron paramagnetic resonance, and X-ray near-edge and extended absorption fine structure revealed that tetrahedrally coordinated Co2+ ions are chemisorbed into the trisiloxane rings on the surface of amorphous silica. In situ XAS shows that Co is not oxidized by air nor reduced by hydrogen even at 650 degrees C. For catalytic propane dehydrogenation, single-site Co2+/SiO2 exhibits selectivities >95% at 550 degrees C and >90% at 650 degrees C with stable activity over 24 h. Calculations with hybrid density functional theory support a non-redox mechanism for activation of C-H and H-H bonds by Co2+ similar to that previously reported for single-site Zn2+/SiO2.

Dehydrogenation↗
DOE OSTI2018

The Influence of Reactor Parameters on the Boron Nitride-Catalyzed Oxidative Dehydrogenation of Propane

In this contribution, we investigate the effect of various reactor parameters on the oxidative dehydrogenation (ODH) of propane using a hexagonal boron nitride (hBN) heterogeneous catalyst. Here, the analysis begins with an assessment of the influence of mass and heat transport on the observed ODH activity. Unexpected experimental results during this analysis prompted us to investigate the use of SiC as an inert catalyst diluent, and we found an increase in propane conversion with increasing diluent content in the reactor. Control experiments suggested that SiC itself is catalytically inactive and that there may be a significant influence of gas-phase chemistry on the observed reactivity.

03 NATURAL GAS↗
DOE OSTI2022

Ce x Zr 1– x O 2 -Supported CrO x Catalysts for CO 2 -Assisted Oxidative Dehydrogenation of Propane–Probing the Active Sites and Strategies for Enhanced Stability

CO 2 -assisted oxidative dehydrogenation of propane (CO 2 -ODH) represents an attractive approach for propylene production and CO 2 utilization. As a soft oxidant, CO 2 can minimize overoxidation of the hydrocarbons to enhance the propylene selectivity while increasing the equilibrium yield. However, a major challenge of CO 2 -ODH is the rapid deactivation of the catalysts. The current study focuses on designing Ce x Zr 1–x O 2 -mixed oxide-supported CrO x catalysts for CO 2 -ODH with enhanced product selectivity and catalyst stability. By doping 0–30% Ce in the Ce x Zr 1–x O 2 mixed oxide support, propane conversion of 53–79% was achieved at 600 °C, with propylene selectivity up to 82%. Compared to the pure ZrO 2 -supported catalyst (i.e., 5 wt %Cr/ZrO 2 ), 20–30 %Ce doped catalysts (i.e., 5 wt %Cr/Ce 0.2 Zr 0.8 O 2 and 5 wt %Cr/Ce 0.3 Zr 0.7 O 2 ) inhibited the formation of CH 4 and ethylene and improved propylene selectivity from 57 to 77–82%. Detailed characterizations of the 5%Cr/Ce 0.2 Zr 0.8 O 2 catalyst and density functional theory (DFT) calculations indicated that Cr 3+ is the active species during the CO 2 -ODH reaction, and the reaction follows a non-redox dehydrogenation pathway. Coke formation was determined to be the primary reason for catalyst deactivation, and the addition of Ce to the ZrO 2 support greatly enhanced the coke resistance, leading to superior stability. Furthermore, coke removal by oxidizing the catalyst in air is effective in restoring its activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis and crystal structures of 5,5'-(propane-2,2-diyl)bis(2-hydroxybenzaldehyde) and 5,5'-(propane-2,2-diyl)bis(2-hydroxyisophthalaldehyde)

The title compounds 5,5'-(propane-2,2-diyl)bis(2-hydroxybenzaldehyde), C 17 H 16 O 4 , ( 1 ), and 5,5'-(propane-2,2-diyl)bis(2-hydroxyisophthalaldehyde), C 19 H 16 O 6 , ( 2 ), crystallize with one molecule in the asymmetric unit. In molecule ( 1 ), a >C(CH 3 ) 2 group bridges two nearly planar salicylaldehyde groups [r.m.s deviations = 0.010 (1) and 0.025 (2) Å], each comprising a planar phenyl ring bonded with a hydroxyl and an aldehyde group. Similarly, compound ( 2 ) has the same bridging group, but it connects two nearly planar appendants [r.m.s deviations = 0.034 (1) and 0.035 (1) Å], each comprising a phenyl ring bonded with a hydroxyl and two aldehyde groups. Molecule ( 1 ) exhibits a bridge angle of 109.5 (2)° with the salicylaldehyde planes subtending a dihedral angle of 88.4 (1)°. In contrast, molecule ( 2 ) presents a bridge angle of 108.9 (2)° with its appendants subtending a dihedral angle of 79.6 (3)°. Both molecules exhibit two intramolecular O—H...O hydrogen bonds involving the phenolic H atoms and carboxyl O-atom acceptors. In the crystal of ( 2 ), O—H...O hydrogen bonds between one of the hydroxyl H atoms and a carboxyl O atom from a symmetry-related molecule form a chain along [10\overline{1}]. In addition, ( 2 ) exhibits a strong visible luminescence when excited with ultraviolet radiation.

Sausa, Rosario C.↗
DOE OSTI2021

Stable and selective catalysts for propane dehydrogenation operating at thermodynamic limit

Hitting the limits on propene synthesis The greater abundance of propane from shale gas has spurred efforts to use it as a propylene feedstock. Direct dehydrogenation catalysts consisting of platinum–tin alloy nanoparticles supported on alumina often must run with hydrogen dilution to avoid carbon buildup and excess tin to avoid alloy segregation. Motagamwala et al. report that platinum–tin nanoparticles interact more weakly with a silica support and the metals thus do not segregate. The use of undiluted reactants allowed the reaction to run near the thermodynamically limit of about 67% conversion with a selectivity to propylene of more than 99%. This catalyst also does not build up carbon and could run up to 30 hours without deactivation. Science , abg7894, this issue p. 217

Science & Technology - Other Topics↗
DOE OSTI2015

Measurements and modeling of high-temperature, high-pressure density for binary mixtures of propane with n-decane and propane with n-eicosane

Binary mixture density data are reported for propane (C 3 ) with n-decane (C 10 ) and with n-eicosane (C 20 ) at T = (320 to 525) K and pressures to 265 MPa. The (C 3 + C 10 ) mixture density data are in good agreement with available literature data to 70 MPa, which is the maximum reported literature pressure. We found that there are no available binary mixture density data to compare to the (C 3 + C 20 ) mixture density data reported in the present study. Furthermore, the mixture density data are correlated with the Tait equation to facilitate interpolation of the data at different experimental conditions. Equations of state that are suitable for reservoir simulations are used to model the reported data. These models include the Peng–Robinson equation of state (PREoS), a volume-translated PREoS fit to high temperature, high pressure (HTHP) pure component density data, the PC-SAFT EoS, and modifications of the PC-SAFT EoS developed for better representation of HTHP data. As a result, the models give superior density predictions for (C 3 + C 10 ) mixtures compared to (C 3 + C 20 ) mixtures.

02 PETROLEUM↗