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At least 37 records · Page 2

Green Aerospace Fuels from Nonpetroleum Sources

Efforts to produce green aerospace propellants from nonpetroleum sources are outlined. The paper begins with an overview of feedstock processing and relevant small molecule or C1 chemistry. Gas-to-liquid technologies, notably Fischer-Tropsch (FT) processing of synthesis gas (CO and H2), are being optimized to enhance the fraction of product stream relevant to aviation (and other transportation) fuels at the NASA Glenn Research Center (GRC). Efforts to produce optimized catalysts are described. Given the high cost of space launch, the recycling of human metabolic and plastic wastes to reduce the need to transport consumables to orbit to support the crew of a space station has long been recognized as a high priority. If the much larger costs of transporting consumables to the Moon or beyond are taken into account, the importance of developing waste recycling systems becomes still more imperative. One promising way to transform organic waste products into useful gases is steam reformation; this well-known technology is currently being optimized by a Colorado company for exploration and planetary surface operations. Reduction of terrestrial waste streams while producing energy and/or valuable raw materials is an opportunity being realized by a new generation of visionary entrepreneurs. A technology that has successfully demonstrated production of fuels and related chemicals from waste plastics developed in Northeast Ohio is described. Technologies being developed by a Massachusetts company to remove sulfur impurities are highlighted. Common issues and concerns for nonpetroleum fuel production are emphasized. Energy utilization is a concern for production of fuels whether a terrestrial operation or on the lunar (or Martian) surface; the term green relates to not only mitigating excess carbon release but also to the efficiency of grid-energy usage. For space exploration, energy efficiency can be an essential concern. Other issues of great concern include minimizing impurities in the product stream(s), especially those that potential health risks and/or could degrade operations through catalyst poisoning or equipment damage. The potential impacts on future missions by such concerns are addressed in closing.

Hepp, Aloysius F.↗

Alternative Fuels Research Laboratory

NASA Glenn has invested over $1.5 million in engineering, and infrastructure upgrades to renovate an existing test facility at the NASA Glenn Research Center (GRC), which is now being used as an Alternative Fuels Laboratory. Facility systems have demonstrated reliability and consistency for continuous and safe operations in Fischer-Tropsch (F-T) synthesis and thermal stability testing. This effort is supported by the NASA Fundamental Aeronautics Subsonic Fixed Wing project. The purpose of this test facility is to conduct bench scale F-T catalyst screening experiments. These experiments require the use of a synthesis gas feedstock, which will enable the investigation of F-T reaction kinetics, product yields and hydrocarbon distributions. Currently the facility has the capability of performing three simultaneous reactor screening tests, along with a fourth fixed-bed reactor for catalyst activation studies. Product gas composition and performance data can be continuously obtained with an automated gas sampling system, which directly connects the reactors to a micro-gas chromatograph (micro GC). Liquid and molten product samples are collected intermittently and are analyzed by injecting as a diluted sample into designated gas chromatograph units. The test facility also has the capability of performing thermal stability experiments of alternative aviation fuels with the use of a Hot Liquid Process Simulator (HLPS) (Ref. 1) in accordance to ASTM D 3241 "Thermal Oxidation Stability of Aviation Fuels" (JFTOT method) (Ref. 2). An Ellipsometer will be used to study fuel fouling thicknesses on heated tubes from the HLPS experiments. A detailed overview of the test facility systems and capabilities are described in this paper.

Surgenor, Angela D.↗

Fischer-Tropsch Catalysts

Catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation. F-T active catalysts are prepared by reduction of certain oxygen deficient mixed metal oxides.

White, James H.↗

Synthesis of adenine, guanine, cytosine, and other nitrogen organic compounds by a Fischer-Tropsch-like process.

Study of the formation of purines, pyrimidines, and other bases from CO, H2, and NH3 under conditions similar to those used in the Fischer-Tropsch process. It is found that industrial nickel/iron alloy catalyzes the synthesis of adenine, guanine, cytosine, and other nitrogenous compounds from mixtures of CO, H2, and NH3 at temperatures of about 600 C. Sufficient sample was accumulated to isolate as solid products adenine, guanine, and cytosine, which were identified by infrared spectrophotometry. In the absence of nickel/iron catalyst, at 650 C, or in the presence of this catalyst, at 450 C, no purines or pyrimidines were synthesized. These results confirm and extend some of the work reported by Kayatsu et al. (1968).

Yang, C. C.↗

Carbon Isotope Measurements of Experimentally-Derived Hydrothermal Mineral-Catalyzed Organic Products by Pyrolysis-Isotope Ratio Mass Spectrometry

We report results of experiments to measure the C isotope composition of mineral catalyzed organic compounds derived from high temperature and high pressure synthesis. These experiments make use of an innovative pyrolysis technique designed to extract and measure C isotopes. To date, our experiments have focused on the pyrolysis and C isotope ratio measurements of low-molecular weight intermediary hydrocarbons (organic acids and alcohols) and serve as a proof of concept for making C and H isotope measurements on more complicated mixtures of solid-phase hydrocarbons and intermediary products produced during high temperature and high pressure synthesis on mineral-catalyzed surfaces. The impetus for this work stems from recently reported observations of methane detected within the Martian atmosphere [1-4], coupled with evidence showing extensive water-rock interaction during Martian history [5-7]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization reactions [8,9]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [10-12]. Further, recent experiments by Fu et al. [13] focus on examining detailed C isotope measurements of hydrocarbons produced by surface-catalyzed mineral reactions. Work described in this paper details the experimental techniques used to measure intermediary organic reaction products (alcohols and organic acids).

Socki, Richard A.↗

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

Socki, Richard A.↗

Origin of organic compounds on the primitive earth and in meteorites

The paper examines the role and relative contributions of different forms of energy to the synthesis of amino acids and other organic compounds on the primitive earth and in the solar nebula. Attention is directed mainly to the activation steps and formation of reactive intermediate compounds. Electric discharges appear to be not only the most efficient energy for amino acid synthesis but also yield a mixture of amino acids that is qualitatively and quantitatively the same as that found in the Murchison carbonaceous chondrite. Ultraviolet light is likely to have played a major role in prebiotic synthesis. The reaction of CO plus H2 plus NH3 on the surface of a Fischer-Tropsch catalyst produces reactive intermediates which lead to amino acids and other organic compounds in a much less efficient way than electric discharges.

Miller, S. L.↗

Origin of organic matter in early solar system. VI - Catalytic synthesis of nitriles, nitrogen bases and porphyrin-like pigments.

A variety of nitrogen compounds have been synthesized by a static Fischer-Tropsch type reaction from CO, D2 and ND3, with Ni-Fe and Al2O3 catalysts. In this reaction, the gas is heated to 500-700 C for about 0.5 hr, and then cycled through lower temperatures (100-400 C) for 1-14 days. Products were analyzed by mass spectrometry in conjunction with gas chromatography and other chromatographic techniques. Compounds produced include alkyl cyanides, pyrroles, porphyrin-like compounds, guanidines, hydantoin, uracil and its derivatives, thymine, adenine, guanine, xanthine, melamine, as well as alkanes, alkenes and aromatic hydrocarbons. Such reactions may have been involved in the production of interstellar molecules, organic compounds in meteorites, and prebiotic organic matter on planets.

Hayatsu, R.↗

Quantification of monocarboxylic acids in the Murchison carbonaceous meteorite

The abundances of some of the straight- and branched-chain isomers of the monocarboxylic acids found in the Murchison carbonaceous chondrite are determined. Monocarboxylic acids extracted from a crushed sample of Murchison interior were quantified by means of gas chromatography and mass spectroscopy after a spiking solution of deuterated analogues of 11 carboxylic acids had been added. Monocarboxylic acid abundances are found to range between 1.83 and 0.01 micromole/g, which is significantly higher than Murchison amino acid concentrations, and to decrease with increasing carbon number for both branched and unbranched molecules. The results are interpreted to support the abiotic extraterrestrial synthesis of monocarboxylic acids. Possible mechanisms leading to the equal synthesis of branched and each unbranched carboxylic acid with the same carbon number are considered, noting that the Fischer-Tropsch Type mechanism by itself is incapable of accounting for the observed distributions.

Lawless, J. G.↗

Carbonaceous chondrites and the origin of life

Organic matter in carbonaceous chondrites can be separated into three fractions. The first component, the fraction that is insoluble in chloroform and methanol, has a part which is of interstellar origin. The other two fractions (chloroform-soluble hydrocarbons and methanol-soluble polar organics) are hypothesized to have been synthesized on a planetoid body. We propose that the polar organics, i.e., amino acids, were synthesized close to its surface by the radiolysis of hydrocarbons and ammonium carbonate in a liquid water environment. Some hydrocarbons may have been synthesized by a Fischer-Tropsch mechanism in the interior of the body. Ferrous ion acted as a protection against back reactions. The simultaneous synthesis of iron-rich clays with the polar organics may be indicative of events related to the origin of life on Earth.

Hartman, Hyman↗

Synthesis of Stacked-Cup Carbon Nanotubes in a Metal Free Low Temperature System

Stacked-cup carbon nanotubes were formed by either Fischer-Tropsch type or Haber Bosch type reactions in a metal free system. Graphite particles were used as the catalyst. The samples were heated at 600 C in a gas mixture of CO 75 Torr, N2 75 Torr and H2 550 Torr for three days. Trans mission electron microscope analysis of the catalyst surface at the completion of the experiment recognized the growth of nanotubes. They were 10-50 nm in diameter and approximately 1 micrometer in length. They had a hollow channel of 5-20 nm in the center. The nanotubes may have grown on graphite surfaces by the CO disproportionation reaction and the surface tension of the carbon nucleus may have determined the diameter. Although, generally, the diameter of a carbon nanotube depends on the size of the cataly1ic particles, the diameter of the nanotubes on graphite particles was independent of the particle size and significantly confined within a narrow range compared with that produced using catalytic amorphous iron-silicate nanoparticles. Therefore, they must have an unknown formation process that is different than the generally accepted mechanism.

Kimura, Yuki↗

Trapping Planetary Noble Gases During the Fischer-Tropsch-Type Synthesis of Organic Materials

When hydrogen, nitrogen and CO arc exposed to amorphous iron silicate surfaces at temperatures between 500 - 900K, a carbonaceous coating forms via Fischer-Tropsch type reactions!, Under normal circumstances such a catalytic coating would impede or stop further reaction. However, we find that this coating is a better catalyst than the amorphous iron silicates that initiate these rcactions:u . The formation of a self-perpetuating catalytic coating on grain surfaces could explain the rich deposits of macromolecular carbon found in primitive meteorites and would imply that protostellar nebulae should be rich in organic materiaL Many more experiments are needed to understand this chemical system and its application to protostellar nebulae.

Nuth, Joseph A.↗

Aerospace Fuels From Nonpetroleum Raw Materials

Recycling human metabolic and plastic wastes minimizes cost and increases efficiency by reducing the need to transport consumables and return trash, respectively, from orbit to support a space station crew. If the much larger costs of transporting consumables to the Moon and beyond are taken into account, developing waste recycling technologies becomes imperative and possibly mission enabling. Reduction of terrestrial waste streams while producing energy and/or valuable raw materials is an opportunity being realized by a new generation of visionary entrepreneurs; several relevant technologies are briefly compared, contrasted and assessed for space applications. A two-step approach to nonpetroleum raw materials utilization is presented; the first step involves production of supply or producer gas. This is akin to synthesis gas containing carbon oxides, hydrogen, and simple hydrocarbons. The second step involves production of fuel via the Sabatier process, a methanation reaction, or another gas-to-liquid technology, typically Fischer-Tropsch processing. Optimization to enhance the fraction of product stream relevant to transportation fuels via catalytic (process) development at NASA Glenn Research Center is described. Energy utilization is a concern for production of fuels whether for operation on the lunar or Martian surface, or beyond. The term green relates to not only mitigating excess carbon release but also to the efficiency of energy usage. For space, energy usage can be an essential concern. Another issue of great concern is minimizing impurities in the product stream(s), especially those that are potential health risks and/or could degrade operations through catalyst poisoning or equipment damage; technologies being developed to remove heteroatom impurities are discussed. Alternative technologies to utilize waste fluids, such as a propulsion option called the resistojet, are discussed. The resistojet is an electric propulsion technology with a powered thruster to vaporize and heat a propellant to high temperature, hot gases are subsequently passed through a converging-diverging nozzle expanding gases to supersonic velocities. A resistojet can accommodate many different fluids, including various reaction chamber (by-)products.

Palaszewski, Bryan A.↗

Organics on Fe-Silicate Grains: Potential Mimicry of Meteoritic Processes?

Currently, it is unknown what exact process or combination of processes produced organics that are found in meteorites or are detected in comets and nebulas. One particular process that forms organics involves Fischer-Tropsch type (FTT) reactions. Fischer-Tropsch type reactions produce hydrocarbons by hydrogenating carbon monoxide via catalytic reactions. The overall reaction is shown. The products of these reactions have been studied using natural catalysts and calculations of the efficiency of FTT synthesis in the Solar Nebula suggest that these types of reactions could make significant contributions to the composition of material near three AU. We use FTT synthesis to coat amorphous Fesilicate grains with organic material to simulate the chemistry in the early Solar Nebula. We used lab-synthesized amorphous Fe-silicate grains for the catalyst because they might better simulate the starting materials found in protostellar nebulas. A brief description of the synthesis of these grains is given in Experiments. This work is different from previous studies because we focus here on the carbonaceous material deposited on the grains. In our experiments, we roughly simulate a model of the nebular environment where grains are successively transported from hot to cold regions of the nebula. In other words, the starting cold regions of the nebula. In other words, the starting gases and FTT products are continuously circulated through the grains at high temperature with intervals of cooling. Overall, organics generated in this manner could represent the carbonaceous material incorporated into comets and meteorites. We present the analyses of the organics produced using pyrolysis gas chromatography mass spectrometry (GCMS) and compare the results with those organics found in the Murchison meteorite.

Johnson, N. M.↗

Origin of life and iron-rich clays

The premise that life began with self-replicating iron-rich clays is explored. In association with these clays and UV light, polar organic molecules, such as oxalic acid, were synthesized. The carbonaceous chondrites have both iron-rich clays and organic molecules. It is convenient to classify meteoritic organic matter into 3 categories: insoluble polymer, hydrocarbons and polar organics (soluble in water). Recent work on the delta D, delta N-15 and delta C-13 has made it clear that these three fractions have been made by three different mechanisms. A significant fraction of the insoluble polymer has a delta-D which suggests that it was made in an interstellar medium. The hydrocarbons seem to have been made on a parent body by a Fischer-Tropsch mechanism. The polar organics were probably synthesized in a mixture of carbonate (NH4)2CO3, Fe(++) ion and liquid water by radiolysis. In a set of experiments the radiolysis of (NH4)2CO3 in the presence and absence of Fe(++) ion has been examined. The synthesis of glycine in the presence of Fe(++) ion is 3-4 times that in the absence of ferrous ion. The effects of the addition of hydrocarbons to this mixture are explored. Iron-rich clays at low temperature and pressure are synthesized. So far the results are not sufficiently crystalline to look for replication. It should be noted that organic chelating agents such as oxalic acid do increase the crystallinity of the clays but not sufficiently. The hydrothermal synthesis of iron-rich clays is being examined.

Hartman, H. H.↗

A Propensity for n-omega-Amino Acids in Thermally-Altered Antarctic Meteorites

Carbonaceous meteorites are known to contain a wealth of indigenous organic molecules, including amino acids, which suggests that these meteorites could have been an important source of prebiotic organic material during the origins of life on Earth and possibly elsewhere. We report the detection of extraterrestrial amino acids in thermally-altered type 3 CV and CO carbonaceous chondrites and ureilites recovered from Antarctica. The amino acid concentrations of the thirteen Antarctic meteorites were generally less abundant than in more amino acid-rich CI, CM, and CR carbonaceous chondrites that experienced much lower temperature aqueous alteration on their parent bodies. In contrast to low-temperature aqueously-altered meteorites that show complete structural diversity in amino acids formed predominantly by Strecker-cyanohydrin synthesis, the thermally-altered meteorites studied here are dominated by small, straight-chain, amine terminal (n-omega-amino) amino acids that are not consistent with Strecker formation. The carbon isotopic ratios of two extraterrestrial n-omega-amino acids measured in one of the CV chondrites are consistent with C-13-depletions observed previously in hydrocarbons produced by Fischer-Tropsch type reactions. The predominance of n-omega-amino acid isomers in thermally-altered meteorites hints at cosmochemical mechanisms for the preferential formation and preservation of a small subset of the possible amino acids.

Burton, Aaron S.↗