High-density Fuels Research Articles

Synthesis of High-Density Jet Fuels from Biomass

Synthesis of High-Density Jet Fuels from Biomass

Advances in Nanocatalyst Design for Biofuel Production

AbstractThe exploitation of nanocatalysts, at the boundary between homogeneous and heterogeneous catalysis, offers new efficient ways to produce renewable biofuels in environmentally friendly conditions. Specifically, biodiesel and high density fuels have been chosen as major topics of research for the design of catalytic nanomaterials. As solid‐state catalysts, they are recyclable, and their nanometric particle size enables high activities that approach those of homogeneous catalysts. In addition, they offer novel and unique catalytic behaviors not accessible to solids above the nanometer range. Furthermore, the use of magnetically active materials has led to the development of nanocatalysts easily recoverable through the application of magnetic fields. In this Minireview, the latest achievements in the production of advanced biofuels using stable, highly active, cheap and reusable nanocatalysts are described.

Selective Hydrogenations in Proton Exchange Membrane Reactor

With the increased demand for environmentally sustainable fuels and chemicals, interest in the conversion of biomass conversion into value-added chemicals and high density fuels has increased. Traditional biomass upgrading processes are carried out thermocatalytically at high temperatures and pressures, and often yield low selectivities. In contrast, electrocatalytic process can be performed at low temperatures and pressures and can utilize renewable electricity. In addition for hydrogenation reactions, high hydrogen concentrations can be achieved. The key to controlling the selectivity of electrocatalytic hydrogenations is identifying appropriate cathode materials. Our group has been exploring the use of early trasition metal carbide based materials for a variety of electrocatalytic and catalytic reactions. Significant improvements in product yields and selectivities have been demonstrated for the electrocatalytic hydrogenation of triglycerides using W2C and Pd/W2C materials. These improved rates have been linked to hydrogen spillover and synergistic effects between Pd and the W2C support. The aim of research described in this paper was to investigate the use of a proton exchange membrane reactor for the electrocatalytic hydrogenation of model biomass species including furfural and crotonaldehyde, and compare the results with those from conventional thermocatalytic processes. Expanding upon previous work, the cathode catalyst consisted of a metal active for hydrogenation (Pd, Co, and Ni) supported on traditional thermocatalyst supports (SiO2 and Al2O3), a traditional electrocatalyst supports (carbon), and Mo2C, a conductive thermocatalyst that has been extensively studied for various hydrogenation reactions. Structural and compositional properties of the materials were linked to their hydrogenation rates and selectivities.

The safety analysis of a small pressurized water reactor utilizing fully ceramic microencapsulated fuel

For post-Fukushima nuclear power plants, accident-tolerant fuel (ATF) is strongly desired in order to prevent radioactive release in the event of a severe accident. The Fully Ceramic Microencapsulated (FCM) fuel is one of these materials. The neutronics and thermal hydraulics analysis of small pressurized water reactor (PWR) utilizing FCM fuels needs to be carried out to demonstrate this fuel performance. In this study, first, a three dimensional full core model of a small PWR design is developed to assess the cycle lengths and power distribution. In order to achieve the acceptable cycle lengths, some design optimizations are taken, including higher TRISO particle packing fraction, higher enrichment and using higher density fuels. The results demonstrate that the acceptable cycle lengths can be achieved after this design optimizations. The results reveal that the cycle lengths can be improved to about 550days after using the 19.9w/o enrichment fuels with UO2 fuel kernel, and the cycle lengths can be maintain about 800days with UN fuel kernel due to the higher density than UO2 fuel kernel. Then, suppressing the excess reactivity, the core power distributions and reactivity coefficients are performed to prepare for thermal hydraulics analysis.The steady state and transient state analysis for LOCA is carried out using the best estimate system code RELAP5. For the conventional UO2 fuel, fission product releases simultaneously when the cladding fails. But for the FCM fuel, the radioactive material can be contained in the fuel pellet even after the cladding failure since enveloping the TRISO particles within a dense SiC matrix provides multiple barriers to fission product release. Consequently, although the Zircalloy cladding fails, there is still 3500s available for operator actions before the start of FCM fuel melting occurs even through the SB-LOCA occurring without ECCS, and there is still 1443s available even through the LB-LOCA occurring without ECCS. The results of the accident analysis without ECCS would be useful in understanding cladding and fuel failure progression and could provide guidelines in establishing detailed accident management procedures to design the proper ECCS in the future.

Synthesis of Renewable High-Density Fuel with Cyclopentanone Derived from Hemicellulose

1-(3-Cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane, a renewable high-density fuel, was first produced in a high overall carbon yield (∼70%) with cyclopenanone that can be derived from hemicellulose. The synthetic route used in this work contains three steps. In the first step, 2-cyclopentyl cyclopentanone was synthesized for the first time by a one-pot reaction of cyclopentanone and hydrogen under the catalysis of Raney metal and alkali hydroxides. Over the optimized catalyst (Raney cobalt + KOH), a high carbon yield (83.3%) of 2-cyclopentyl cyclopentanone was achieved at 353 K. In the second step, 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was produced in a high carbon yield (95.4%) by the solvent-free self-aldol condensation of 2-cyclopentyl cyclopentanone under the vacuum conditions. In the third step, the 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was hydrodeoxygenated over the Ni-SiO2 catalyst under solvent-free conditions. High carbon yields of 1-(3-cyclopen...

Renewable high density fuels containing tricyclic sesquiterpanes and alkyl diamondoids

High density fuels are prepared from bio-derived tricyclic sesquiterpenes. Acid catalyzed isomerization lowers the viscosity and increases the cetane number.

Sensitivity study for accident tolerant fuels: Property comparisons and behavior simulations in a simplified PWR to enable ATF development and design

Since the events at the Fukushima-Daiichi nuclear power plant, there has been increased interest in developing fuels to better withstand accidents for current light water reactors. Four accident tolerant fuel candidates are uranium oxide with beryllium oxide additives, uranium oxide with silicon carbide matrix additives, uranium nitride, and uranium nitride with uranium silicide composite. The first two candidates represent near-term high performance uranium oxide with high thermal conductivity and neutron transparency, and the second two represent mid-term high-density fuels with highly beneficial thermal properties. This study seeks to understand the benefits and drawbacks of each option in place of uranium dioxide. To assess the material properties for each of the fuel types, an extensive literature review was performed for material property data. Correlations were then made to evaluate the properties during reactor operation. Neutronics and thermal hydraulics studies were also completed to determine the impact of the use of each candidate in an AP1000 reactor. In most cases, the candidate fuels performed more desirably than uranium dioxide, but no fuel type performed better in all aspects. Much more research needs to be performed to build a complete model of the fuel performances, primarily experimental data for uranium silicide. Each of the fuels studied has its own benefits and drawbacks, and the comparisons discussed in this report can be used to aid in determining the most appropriate fuel depending on the desired specifications.

Iron Oxide Plasmonic Nanostructures for Energy Harvesting

Recently Iron oxide (Fe2O3) nano structure has drawn renewed interest in electrocatalysis process for carbon-carbon (C-C) bond breaking in ethanol. We design and fabricate Fe2O3 plasmonic nanostructures for C-C bond-breaking processes in high density fuels. After patterning Fe2O3 film, we use inductively coupled plasma (ICP) etching equipped with an Argon (Ar) plasma to create the film with nanometer scale dimensions. We used both photoresist mask and hard mask like silicon dioxide film for selecting etching. Fe2O3 film etching process is optimized by using different parameters like ICP power, base electrode power, pressure, temperature, and Ar gas flow etc. We used elliposmetric method as well as UV/Vis reflectance spectroscopy to determine the resonance wavelength of the plasmonic nanostructures suitable for electrocatalysis experiment. Iron oxide (Fe2O3) has recently received much attention among the various semiconductor photo-electrode materials due to its favorable optical band gap (~2.2 eV), excellent chemical stability in high pH media, natural abundance, and low cost [1,2]. However, Fe2O3 exhibits a relatively poor absorptivity of photons near its band-edge due to an indirect band gap, poor electronic conductivity (PEC), and picosecond recombination of excited states, thus leading to a photo-generated hole diffusion length of ~2-4 nm [3]. These non-ideal optoelectronic properties hinder the transport of photo-generated carries and increase the recombination rate, which results in a lowering of the PEC efficiency compared to theoretically predicted values. Controlling the nanostructure of Fe2O3 may provide an effective technology for overcoming the aforementioned problems of Fe2O3 due to the geometry and mechanism-dependent semiconductor structure [4]. The shape of the Fe2O3structures with cone, cylinder, sphere, etc. features alters the electric field dependent absorption and transport processes. We use electron beam evaporation system to deposit thin Fe2o3 film (100-500 nm) on silicon substrate with thin layer of gold (Au) film. We then use an inductively coupled plasma (ICP) etching process to define Fe2O3 nano-structured pillars with various diameters (50nm -5 µm) and heights. We use either e-beam lithography or optical lithography process to define the plasmonic nanostructures. ICP etching process with Ar plasma is used with varying power, pressure and substrate temperature etc. to optimize the Fe2O3 etching process. Scanning electron (SEM) and atomic force (AFM) microscopy tools are used to determine the surface morphology of the nanostructures, whereas ellipsometer and UV-Vis spectrometer elucidate the optical properties. Galvanometeric current-voltage measurement is performed to determine the optimum nano plasmonic structure for carbon-carbon (C-C) bond breaking process in high energy density chemicals. In figure 1, we have shown the etch rate of Fe2O3 film with different substrate temperatures and Ar pressure in the reaction chamber. We find that in order to achieve a smooth surface and reasonable etch rate, the substrate temperature should be between 15-18 ᵒC and the ICP power between 800-1000 W. Detailed deposition, annealing, etching and characterization results of Fe2O3 nano plasmonic structures will be presented in a full paper.

Biosynthesis of β-caryophyllene, a novel terpene-based high-density biofuel precursor, using engineered Escherichia coli

β-caryophyllene is a common sesquiterpene compound currently being studied as a promising precursor for the production of high-density fuels. Acute demand for high-density fuels has provided the impetus to pursue biosynthetic methods to produce β-caryophyllene from reproducible sources. In this study, we produced β-caryophyllene by assembling a biosynthetic pathway in an engineered Escherichia coli strain of which phosphoglucose isomerase gene has been deleted. The 1- deoxy-d-xylulose 5-phosphate (DXP) or heterologous mevalonate (MVA) pathways were employed. Meanwhile, geranyl diphosphate synthase, glucose-6-phosphate dehydrogenase and β-caryophyllene synthase genes were co-overexpressed in the above strain. The final genetically modified strain, YJM59, produced 220 ± 6 mg/L of β-caryophyllene in flask culture. We also evaluated the use of fed-batch fermentation for the production of β-caryophyllene. After induction for 60 h, the YJM59 strain produced β-caryophyllene at a concentration of 1520 mg/L. The volumetric production fermented in the aerobic fed-batch was 0.34 mg/(L·h·OD600) and the conversion efficiency of glucose to β-caryophyllene (gram to gram) was 1.69%. Our results are the first successful attempt to produce β-caryophyllene using E. coli BL21(DE3), and provide a new strategy that is green and sustainable for the production of β-caryophyllene.

Iron(III)-Catalyzed Dimerization of Cycloolefins: Synthesis of High-Density Fuel Candidates

Bicycloalkanes with the potential for deployment in high-density diesel and jet fuels can be conveniently generated from cycloolefins using a two-step process. Dimerization of the cycloolefin may be affected, catalytically, using commercially available Fe(III) salts, and the reaction is tolerant of ring size (C5–C8) and limited ring-substitution patterns. Generation of an allylic radical is strongly suggested; however, observation of Fe-catalyzed olefin rearrangements and transfer dehydrogenation reactions may implicate the involvement of discrete organometallic complexes in the reaction. The fully saturated bicycloalkanes are easily prepared via metal-catalyzed hydrogenation of the cycloolefin–cycloalkane dimeric species.

Synthesis Chemistry of High-Density Fuels for Aviation and Aerospace Propulsion

Synthesis Chemistry of High-Density Fuels for Aviation and Aerospace Propulsion

もみ殻を原料とする高密度·高硬度固体燃料の常温·高温圧縮強度特性に及ぼす粉砕粒径の影響

もみ殻を原料とする高密度·高硬度固体燃料の常温·高温圧縮強度特性に及ぼす粉砕粒径の影響

Catalytic isomerization and oligomerization of endo-dicyclopentadiene using alkali-treated hierarchical porous HZSM-5

Transferring endo-dicyclopentadiene (endo-DCPD) into exo-isomer and exo-tricyclopentadiene (TCPD) has great potential in synthesizing high-density fuels, but microporous acidic zeolites show low activity due to the mass transfer limitation and shape selectivity. Herein, we successfully tuned HZSM-5 into high activity by generating hierarchical pores via alkali treatment. XRD, SEM, TEM, N2 adsorption/desorption and 27Al MAS NMR characterizations confirm that moderate alkali treatment removes the amorphous phase and producess mesopores connecting microchannels, but the framework collapses under rigorous conditions. NH3-TPD and pyridine adsorption IR indicate that the presence of mesopores increases the accessibility of acid sites in microchannles, especially for large molecules. In the isomerization of endo-DCPD, after the generation of hierarchical porosity, the inactive parent HZSM-5 shows a higher exo-DCPD yield than thiose of microporous Hβ and mesoporous Al-MCM-41. In the oligomerization reaction, hierarchical HZSM-5 shows a higher TCPD yield than that of Hβ and the yield is comparable to that of Al-MCM-41. Importantly, this work provides an easy way to produce exo-DCPD and TCPD with maximum yield respectively by adjusting the zeolite treatment and reaction conditions. Z5-70–0.5–1.0 shows the best performance for isomerization whereas Z5-80–0.5–1.0 possessing more mesopores is most suitable for oligomerization. The hierarchical porous zeolite shows excellent coke tolerance, and shows good stability in recycling.

Low-temperature, solvent-free dehydration of cineoles with heterogeneous acid catalysts for the production of high-density biofuels

BACKGROUND Oxygenated terpenoids such as 1,4-cineole and 1,8-cineole can be major components of turpentine and essential oils. These terpenoids can also be produced from sugars via a biosynthetic approach. Catalytic deoxygenation of these substrates has the potential to efficiently generate commercially important chemicals and high density fuels for turbine or diesel propulsion. RESULTS The low-temperature deoxygenation reactions of 1,4-cineole and 1,8-cineole over the heterogeneous acid catalysts Amberlyst-15, Nafion SAC-13, and Montmorillonite K10 have been studied. 1,4-cineole was found to isomerize to terpinene-1-ol followed by dehydration to a mixture primarily composed of α- and γ-terpinene. In a similar manner, 1,8-cineole was found to isomerize to α-terpineol followed by dehydration to primarily terpinolene and α-terpinene. Amberlyst-15 was the most active catalyst on a mass basis and gave 100% conversion of 1,4-cineole in 24 h at 85°C. Longer reaction times or higher reaction temperatures led to significant conversion of the dehydrated monoterpenes to diterpenes. Similar trends were observed for Nafion SAC-13 and Montmorillonite K10. CONCLUSION This work provides important mechanistic information regarding the dehydration chemistry of cineoles and shows the potential of heterogeneous acid catalysts to effectively convert oxygenated terpenoids to high density hydrocarbon mixtures with potential uses as renewable diesel fuels. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

High-density biosynthetic fuels: the intersection of heterogeneous catalysis and metabolic engineering.

Biosynthetic valencene, premnaspirodiene, and natural caryophyllene were hydrogenated and evaluated as high performance fuels. The parent sesquiterpenes were then isomerized to complex mixtures of hydrocarbons with the heterogeneous acid catalyst Nafion SAC-13. High density fuels with net heats of combustion ranging from 133-141 000 Btu gal(-1), or up to 13% higher than commercial jet fuel could be generated by this approach. The products of caryophyllene isomerization were primarily tricyclic hydrocarbons which after hydrogenation increased the fuel density by 6%. The isomerization of valencene and premnaspirodiene also generated a variety of sesquiterpenes, but in both cases the dominant product was δ-selinene. Ab initio calculations were conducted to determine the total electronic energies for the reactants and products. In all cases the results were in excellent agreement with the experimental distribution of isomers. The cetane numbers for the sesquiterpane fuels ranged from 20-32 and were highly dependent on the isomer distribution. Specific distillation cuts may have the potential to act as high density diesel fuels, while use of these hydrocarbons as additives to jet fuel will increase the range and/or time of flight of aircraft. In addition to the ability to generate high performance renewable fuels, the powerful combination of metabolic engineering and heterogeneous catalysis will allow for the preparation of a variety of sesquiterpenes with potential for pharmaceutical, flavor, and fragrance applications.

Synthesis of renewable high-density fuels using cyclopentanone derived from lignocellulose

By the combination of solvent-free aldol condensation and one-step hydrodeoxygenation under mild reaction conditions, a high-density (0.866 g mL(-1)) bicyclic C10 hydrocarbon was synthesized in high overall yield (up to 80%) using cyclopentanone derived from lignocellulose.

Ionic Liquid Catalytic Rearrangement of Polycyclic Hydrocarbons: A Versatile Route to Alkyl-Diamondoid Fuels

Rearrangement of three types of fused polycyclic hydrocarbons with carbon atoms 12–14 was conducted using chloroaluminate ionic liquid (IL) as acid catalyst. The hydrocarbons undergo quick configurational isomerization and then skeletal rearrangement toward alkyl-adamantanes. Although having different molecular structure, these hydrocarbons all lead to adamantanes substituted with 2–3 methyl and/or ethyl groups. The alkyl-adamantanes show high density, low freezing point and viscosity, and are very attractive as high-density fuels. Computation using density functional theory confirms that alkyl-adamantanes are thermodynamically favored and explains the experimental product distribution very well. On this basis, the reaction pathway of each hydrocarbon was illustrated. The reaction conditions including acidity (AlCl3 fraction), temperature, and IL dosage show significant effect on the rearrangement. Moreover, the distribution of alkyl-adamantanes can be tuned by adjusting the reaction conditions, allowing ...

Low-Temperature Properties of Renewable High-Density Fuel Blends

The low-temperature properties of high-density terpene dimer fuels and fuel mixtures with JP-8, JP-10, and hydrogenated pinene have been studied by shear viscometry and thermomechanical analysis (TMA). Neat terpene dimers have a viscosity of 3.94 × 103 mPa·s at −10 °C, while 50:50 mixtures with JP-10, RJ-4, pinane, and JP-8 have viscosities 2–3 orders of magnitude lower at 23.9, 53.0, 24.9, and 3.7 mPa·s, respectively. Linear and branched alkanes in JP-8 disrupt glass formation of the dimers, explaining the significant difference between the viscosity afforded by bicyclic diluents and JP-8. To complement the viscosity data, TMA was used to observe low-temperature transitions (Tm and Tg) of the blended fuels. Mixtures of the terpene dimers with cyclic molecules show only glass transition temperatures with no observable melting points, while mixtures with JP-8 and decane show Tg values that transition to melting points at high concentrations of terpene dimers. The results suggest that blending conventional fuels with terpene dimers is an effective strategy for mitigating the high viscosity of the C20 molecules. In addition, blending these renewable fuels with conventional jet fuel (JP-8) imparts both a higher density as well as an improved volumetric net heat of combustion while maintaining an acceptable low-temperature viscosity when compared to JP-8 alone.

Efficient conversion of pure and mixed terpene feedstocks to high density fuels

A series of high density renewable fuels has been synthesized through selective dimerization of α-pinene, camphene, limonene, and crude turpentine using the heterogeneous catalysts Nafion, Nafion SAC-13, and Montmorillonite K-10. Terpene dimers are produced in up to 90% yield depending on the feedstock. The preferred catalyst, Nafion SAC-13, could be recovered by simple filtration and reused up to eight times without any significant decrease in activity. The fuels produced by this process have net heats of combustion ranging from 137,000 to 142,000btu/gal which are comparable to the tactical missile fuel JP-10. Fuels derived from both α-pinene and camphene have similar viscosities, densities, and net heats of combustion due to isomerization of α-pinene to camphene prior to dimerization. In contrast, limonene dimers exhibit a much lower density and viscosity due to their ring opened structures. DSC analysis of the dimer fuels revealed freezing points of −54, −52, and −78°C for dimers derived from camphene, α-pinene, and limonene, respectively. Empirical results and a terpene adsorption study suggest that the dimerization reaction proceeds through initial coordination of α-pinene to catalytic sites followed by cross-coupling with camphene. The ultra-performance renewable fuels described in this work have potential applications as significant components of jet, diesel, and tactical fuels.

Steady-state neutronic analysis of converting the UK CONSORT reactor for ADS experiments

CONSORT is the UK’s last remaining civilian research reactor, and its present core is soon to be removed. This study examines the feasibility of re-using the reactor facility for accelerator-driven systems research by replacing the fuel and installing a spallation neutron target driven by an external proton accelerator. MCNP5/MCNPX were used to model alternative, high-density fuels and their coupling to the neutrons generated by 230 MeV protons from a cyclotron striking a solid tungsten spallation target side-on to the core. Low-enriched U 3Si 2 and U–9Mo were considered as candidates, with only U–9Mo found to be feasible in the compact core; fuel element size and arrangement were kept the same as the original core layout to minimise thermal hydraulic and other changes. Reactor thermal power up to 2.5 kW is predicted for a k eff of 0.995, large enough to carry out reactor kinetic experiments.