Abstract  We report the one-pot alkylation of mesitylene with carbohydrate-derived 5-(hydroxymethyl)furfural (HMF) as a step toward diesel-range liquids. Using FeCl(3) as a catalyst, HMF is shown to alkylate toluene, xylene, and mesitylene in high yields in CH(2)Cl(2) and MeNO(2) solvents. Efforts to extend this reaction to greener or safer solvents showed that most ether-based solvents are unsatisfactory. Acid catalysts (e.g, p-TsOH) also proved to be ineffective. Using formic acid as a reactive solvent, mesitylene could be alkylated to give mesitylmethylfurfural (MMF) starting from fructose with yields up to approximately 70 %. The reaction of fructose with formic acid in the absence of mesitylene gave rise to low yields of the formate ester of HMF, which indicates the stabilizing effect of replacing the hydroxyl substituent with mesityl. The arene also serves as a second phase into which the product is extracted. Even by using formic acid, the mesitylation of less expensive precursors such as glucose and cellulose proceeded only in modest yields (ca. 20 %). These simpler substrates were found to undergo mesitylation by using hydrogen chloride/formic acid via the intermediate chloromethylfurfural.

Abstract  The complete hydrogenation of aromatic molecules is one of the key transformation employed in the synthetic and petroleum chemistry. Described herein is a new catalytic nanomaterial for the hydrogenation of neat aromatics under mild conditions. A novel nanocatalyst, consisting of iridium(O) nanoparticles stabilized by zeolite with EAU framework could reproducibly been prepared from the reduction of iridium(III)-exchanged zeolite in an aqueous sodium borohydride solution at room temperature and characterized by ICP-MS, P-XRD, HRTEM, XPS, N-2-Ads.-Des., and P(C6H11)(3) poisoning. The results reveal the formation of iridium(O) nanoparticles of 5.8 +/- 2.1 nm size dispersed on the external surface along with iridium(O) nanolclusters in cavities of zeolite-Y whereby the host matrix remains intact. The resulting iridium(O) nanoparticles were employed as heterogeneous catalyst in the hydrogenation of various aromatic substrates (benzene, toluene, o-xylene and mesitylene) in the solvent-free systems at room temperature and 3 bar initial Hy pressure. They are highly active catalyst in the hydrogenation of neat aromatics, such as they can completely hydrogenate benzene to cyclohexane with an initial turnover frequency value of TOE= 3215 h(-1). Moreover, they show high durability against to leaching and sintering throughout the catalytic runs, which make them reusable catalyst. More importantly, testing the catalytic lifetime of our iridium(O) nanoparticles showed that they provide previously unprecedented total turnover number of TO = 197,000 over 92 h before deactivation in the hydrogenation of benzene at room temperature and 3 bar initial H-2 pressure. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  Aviation fuel (i.e., jet fuel) requires a mixture of C9 -C16 hydrocarbons having both a high energy density and a low freezing point. While jet fuel is currently produced from petroleum, increasing concern with the release of CO2 into the atmosphere from the combustion of petroleum-based fuels has led to policy changes mandating the inclusion of biomass-based fuels into the fuel pool. Here we report a novel way to produce a mixture of branched cyclohexane derivatives in very high yield (>94 %) that match or exceed many required properties of jet fuel. As starting materials, we use a mixture of n-alkyl methyl ketones and their derivatives obtained from biomass. These synthons are condensed into trimers via base-catalyzed aldol condensation and Michael addition. Hydrodeoxygenation of these products yields mixtures of C12 -C21 branched, cyclic alkanes. Using models for predicting the carbon number distribution obtained from a mixture of n-alkyl methyl ketones and for predicting the boiling point distribution of the final mixture of cyclic alkanes, we show that it is possible to define the mixture of synthons that will closely reproduce the distillation curve of traditional jet fuel.

Abstract  Cellulose has been widely used to synthesize chiral stationary phases for liquid chro- matography, but it is still absent in the family of stationary phases of gas chromatography due to its poor film-forming property. Based on the unique dissolution characteristic, ionic liquids provide a great chance to solve this problem. In this paper, cellulose triacetate (CTA) was syn- thesized, and then mixed with the home-made polysiloxane ionic liquid (PIL-C12-NTf2) to pro- duce a novel mixed stationary phase (CTA@ PIL-C12-NTf2). After that, it was used to prepare a capillary column for gas chromatography. The column efficiency was measured to be 3,165 plates/m (110 °C, naphthalene, k = 4.95), demonstrating the excellent film-forming capability of this stationary phase, and then the solvation parameter model was employed to find out the interaction parameters of CTA@ PIL-C12-NTf2. In the aspect of selectivity, CTA was firstly demonstrated to be able to improve the resolutions of tri-substituted aromatic positional isomers and the six isomers of nonane (C9). Moreover, some mixtures of representative chemicals like di-substituted aromatic positional isomers, n-alkanes, alcohols, aliphatic esters and phthalates can also be separated well on CTA@ PIL-C12-NTf2. This work proposed a novel way for the application of cellulose modified stationary phase of gas chromatography, and revealed some features of this stationary phase in selectivity resulting from cellulose.

Abstract  This paper reports a unique GC-on-chip module comprising a monolithically integrated semi-packed micro separation column (μSC) and a highly sensitive micro helium discharge photoionization detector (μDPID). While semi-packed μSC with atomic layer deposited (ALD) alumina as a stationary phase provides high separation performance, the μDPID implemented for the first time in a silicon-glass architecture inherits the desirable features of being universal, non-destructive, low power consumption (1.4 mW), and responsive. The integrated chip is 1.5 cm × 3 cm in size and requires a two-mask fabrication process. Monolithic integration alleviates the need for transfer lines between the column and the detector which improves the performance of the individual components with overall reduced fabrication and implementation costs. The chip is capable of operating under the isothermal as well as temperature and flow programming conditions to achieve rapid chromatographic analysis. The chip performance was investigated with two samples: 1) a multi-analyte gas mixture consisting of eight compounds ranging from 98 °C to 174 °C in boiling point and 2) a mixture containing higher alkanes (C9-C12). Our experiments indicate that the chip is capable of providing rapid chromatographic separation and detection of these compounds (<1 min) through the optimization of flow and temperature programming conditions. The GC-on-chip demonstrated a minimum detection limit of ~10 pg which is on a par with the widely used destructive flame ionization detector (FID).

Abstract  Fluid velocities in a continuous-flow, cylindrical, supercritical-water reactor are examined and mathematically modeled using a simplified Navier-Stokes equation. Within the system, a large number of moles of small gaseous species are generated from large molecules of JP-8 jet fuel, causing the fluid to accelerate through the length of the reactor. This net increase in moles leads to a nonconstant fluid density and is modeled using the Peng-Robinson equation of state. Several assumptions are made to make this system readily solvable. The simulation results show that the density change and net generation of moles lead to significant increases in the fluid velocities as the products move down the reactor. Typical reactant feed rates of JP-8 jet fuel (0.5 gmin(-1) and 1.0 gmin(-1)) are modeled based upon previous experimental data performed in a tubular reactor with a length of 75.6 cm and an inner diameter of 2.54 cm.

Abstract  This work explored the formation mechanism of marine oil snow (MOS) and the associated transport of oil hydrocarbons in the presence of a stereotype oil dispersant, Corexit EC9500A. Roller table experiments were carried out to simulate natural marine processes that lead to formation of marine snow. We found that both oil and the dispersant greatly promoted the formation of MOS, and MOS flocs as large as 1.6-2.1 mm (mean diameter) were developed within 3-6 days. Natural suspended solids and indigenous microorganisms play critical roles in the MOS formation. The addition of oil and the dispersant greatly enhanced the bacterial growth and extracellular polymeric substance (EPS) content, resulting in increased flocculation and formation of MOS. The dispersant not only enhanced dissolution of n-alkanes (C9-C40) from oil slicks into the aqueous phase, but facilitated sorption of more oil components onto MOS. The incorporation of oil droplets in MOS resulted in a two-way (rising and sinking) transport of the MOS particles. More lower-molecular-weight (LMW) n-alkanes (C9-C18) were partitioned in MOS than in the aqueous phase in the presence of the dispersant. The information can aid in our understanding of dispersant effects on MOS formation and oil transport following an oil spill event.

Abstract  The structural properties of three small gadolinium carboxylate complexes in three liquid scintillator solvents (pseudocumene, linear alkylbenzene, and phenyl xylylethane) were theoretically investigated using density functional theory (B3LYP/LC-RECP) and polarizable continuum model (PCM). The average interaction energy between gadolinium atom and carboxylate ligand (E(int)) and the energy difference of the highest singly occupied molecular orbital and lowest unoccupied molecular orbital (Δ(SL)) were calculated to evaluate and compare the relative stability of these complexes in solvents. The calculation results show that the larger (with a longer alkyl chain) gadolinium carboxylate complex has greater stability than the smaller one, while these gadolinium carboxylates in linear alkylbenzene were found to have greater stability than those in the other two solvents.

Abstract  Four tetramethyl 4,4'-(ethane-1,2-diylidene)bis[1-R-5-oxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate] compounds, denoted class (1), are a series of conjugated buta-1,3-dienes substituted with a heterocyclic group. The compounds can be used as dyes and pigments due to their long-range conjugated systems. Four structures were studied using (1)H NMR, (13)C NMR and mass spectroscopy, viz. with R = 2,4,6-trimethylphenyl, (1a), R = cyclohexyl, (1b), R = tert-butyl, (1c), and R = isopropyl, (1d). A detailed discussion is presented regarding the characteristics of the three-dimensional structures based on NMR analysis and the X-ray crystal structure of (1a), namely tetramethyl 4,4'-(ethane-1,2-diylidene)bis[5-oxo-1-(2,4,6-trimethylphenyl)-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate], C36H36N2O10. The conjugation plane and stability were also studied via quantum chemical calculations.

Abstract  The irradiation of L-tryptophan, L-tyrosine and 4-phenoxyphenol in aqueous solution produced compounds with similar fluorescence properties as humic substances, and with absorption spectra that were significantly extended into the UVA and visible regions compared to the starting compounds. The irradiated systems had photosensitizing properties, as proven by the photodegradation of 2,4,6-trimethylphenol and furfuryl alcohol (probes of excited triplet states and (1)O2, respectively). The described photochemical processes could constitute an additional pathway for the formation of humic substances in clear and shallow water bodies, which would be added to the complex network of reactions involving dissolved organic matter.

Abstract  In this work we report results related to the improvement of optical and structural properties of thin films of P3HT:PCBM blends grown on ITO and FTO substrates by spin coating using new solvents; the effect of annealing and solvent type on the optical and structural properties is evaluated through spectral absorbance, XRD (x-ray diffraction), Raman spectroscopy and fluorescence microscopy measurements. The studies revealed that the use of these new solvents allowed to grow PCBM:P3HT blends with improved properties for use as active layer of organic cells with bulk heterojunction structure. This samples exhibit high degree of crystallographic ordering, high absorbance in the visible region, low fluorescence and proven formation of PCBM/P3HT heterointerfaces. In particular the PCBM:P3HT films prepared using mesitylene based solution have better spectral absorbance and molecular ordering than those prepared using conventional solvents such as chlorobenzene, dichlorobenzene or toluene.

Since the P3HT:PCBM blend does not dissolve well in mesitylene at room temperature, thin films of P3HT:PCBM blends were prepared using mixtures of mesitylene and other solvents heated at different temperatures. The results revealed that the blends prepared using pure mesitylene stirred and heated to 100 degrees Cprior to deposition,lead totheformationof cluster free layers with good homogeneity, crystallinity and spectral absorbance.

Abstract  Desulfurized JP-8 fuel is of great interest for use as the hydrogen feedstock of fuel cells. The refractory aromatic sulfur species present, however, are particularly challenging to remove through traditional methods. We report the first use of mesoporous silica nanoparticles (MSN) for desulfurization and the material displays a four-fold greater performance towards JP-8 fuel over previous sorbents. The bulk form of mesoporous silica shows three-fold greater level of desulfurization. Silver-impregnated nanoparticle and bulk MCM-41 were found to have saturation adsorption capacities of 32.6 mgS g(-1) and 25.4 mgS g(-1), respectively. MSN display a high capacity for the notoriously difficult to remove 4,6-dimethyldibenzothiophene along with a two-fold improvement in breakthrough capacity over previously published materials, of 0.98 mgS g(-1) at 10 ppm(w)S.

Abstract  Hollow magnetic mesoporous SiO2/Fe3O4 microspheres with different mesopore sizes were synthesized by a simple multi-step solution growth process. In the experiment of coating mesoporous SiO2, cetyltrimethylammonium bromide (CTAB) was used as surfactant and two swelling agents, decane and 1, 3, 5- trimethylbenzene (TMB), were used as swelling agents alone or together with different sequence. The results showed that the magnetic mesoporous SiO2/Fe3O4 microspheres have a saturation magnetization of 13.6 emu-g(-1) and a low coercivity (50 Oe). Different adding form of swelling agents had great effect on the microstructure of mesoporous SiO2/Fe3O4 microspheres. The mesoporous SiO2/Fe3O4 microspheres obtained by using two swelling agents together had better mesoporous properties. The mesoporous SiO2/Fe3O4 microspheres exhibited high surface area (850 m(2).g(-1)), large peak pore (3.11 nm), high pore volume (1.23 cm(3).g(-1)). Moreover, the composite microspheres had larger adsorption amount (276 mg/g) and quicker adsorption rate (0.178 g/(mg.h)) of laccase.

Abstract  Dissolved organic matter (DOM) is both a promoter and an inhibitor of triplet-induced organic contaminant oxidation. This dual role was systematically investigated through photochemical experiments with three types of DOM of terrestrial and aquatic origins that were preoxidized to varying extents by ozonation. The inhibitory effect of DOM was assessed by determining the 4-carboxybenzophenone photosensitized transformation rate constants of two sulfonamide antibiotics (sulfamethoxazole and sulfadiazine) in the presence of untreated or preoxidized DOM. The inhibitory effect decreased with the increasing extent of DOM preoxidation, and it was correlated to the loss of phenolic antioxidant moieties, as quantified electrochemically, and to the loss of DOM ultraviolet absorbance. The triplet photosensitizing ability of preoxidized DOM was determined using the conversion of the probe compound 2,4,6-trimethylphenol (TMP), which is unaffected by DOM inhibition effects. The DOM photosensitized transformation rate constants of TMP decreased with increasing DOM preoxidation and were correlated to the concomitant loss of chromophores (i.e., photosensitizing moieties). The combined effects of DOM preoxidation on the inhibiting and photosensitizing properties were assessed by phototransformation experiments of the sulfonamides in DOM-containing solutions. At low extents of DOM preoxidation, the sulfonamide phototransformation rate constants remained either unchanged or slightly increased, indicating that the removal of antioxidant moieties had larger effects than the loss of photosensitizing moieties. At higher extents of DOM preoxidation, transformation rates declined, mainly reflecting the destruction of photosensitizing moieties.

Abstract  A pair of carbohydrate model compounds, methyl beta-D-glucopyranoside (MGP) and a deuterated MGP labeled at each C-H bond, was reacted with active oxygen species (AOS) generated from reactions between O-2 and a co-existing phenolic compound, 2,4,6-trimethylphenol (TMPh) or 4-hydroxy-3-methoxybenzyl alcohol (vanillyl alcohol, Valc), under O-2 delignification conditions. The pair were also reacted with O radical anion generated in the alkaline H2O2 treatment with the addition of FeCl3. Clear kinetic isotope effects were observed only in the reactions of two pairs using the deuterated MGPs labeled at the anomeric and C-2 positions in this system. These results suggest that at least a specific AOS is generated only in this system and that a major AOS in the O(2)(-)Valc system is highly reactive O radical anion It is also suggested that the AOS specifically generated only in this system is a peroxyl radical derived by the combination reaction between the TMPh phenoxyl radical and O-2.

Abstract  Synthesis of xylene by transalkylation of 1, 2, 4 trimethylbenzene with toluene over cerium modified beta zeolite has been investigated in the present study. The reaction has been carried out in a fixed bed down-flow reactor. The effect of various process parameters: temperature (623-723K), reactant ratio (0.5-4) and space time (0.88-2.9 kg h/kmol), on the toluene conversion and xylene selectivity are investigated. Zeolites with different amount of cerium loading (4.12 wt%, 6.54 wt%, 8.1 wt% and 10.34 wt%) have been prepared and characterized. Zeolite having 8.1wt% cerium loading is proved to be the most active catalyst. Maximum toluene conversion of 58.77% is achieved at a temperature-698K, reactant ratio-3:1, space time-2.9 kg h/kmol. The kinetic runs have been carried out to choose the zone in which the mass transfer effects are negligible. Based on product distribution, a mechanism for the formation of xylene over the modified catalyst is proposed along with a rate expression. The kinetic and adsorption constants of the rate equations are estimated by non-linear regression. The activation energy is found to be 122:41 kJ/mol which compares well with those reported in the literature for transalkylation reaction over similar catalysts.

Abstract  Nickel(II) complexes have attracted much attention as a new generation of olefin catalysts since the α-diiminonickel complex was discovered as a highly efficient procatalyst for ethylene polymerization. A series of novel 4-arylimino-1,2,3-trihydroacridylnickel(II) dihalide complexes was synthesized in a one-pot reaction of 2,3-dihydroacridine-4-one and different anilines with nickel(II) chloride or nickel(II) bromide 1,2-dimethoxyethane complex. The complexes were characterized by infrared spectroscopy and elemental analysis. The molecular structures of the representative complexes 4-(2,6-diisopropylphenylimino)-1,2,3-trihydroacridylnickel(II) dichloride (C3), 4-(2,4,6-trimethylphenylimino)-1,2,3-trihydroacridylnickel dichloride(II) (C4), and 4-(2,4,6-trimethylphenylimino)-1,2,3-trihydroacridylnickel(II) dibromide (C9) were confirmed by single-crystal X-ray crystallography, revealing a distorted tetrahedral geometry around the nickel(II) of C3 and distorted trigonal bipyramidal geometry for C4 and C9. With the activation of trimethylaluminium (TMA), all nickel(II) complexes exhibited good activity for ethylene oligomerization, and oligomer products ranged from butene (C4) to hexadecene (C16).

Abstract  The United States Marine Corps (USMC) utilizes Forward Operating Bases (FOBs) which employ multiple generation units, typically ranging from 2-200 kW in size, and primarily powered by JP-8 (similar to diesel fuel). It is often true that logistical support to deliver fuel is both expensive and dangerous. In typical deployment scenarios today, generation units are attached to a small group of loads, and are frequently operated far from their optimum efficiency. Future plans include combining multiple generators into a single microgrid. Since the generators have different fuel consumption curves, the dispatch of load to generation must account for unit capabilities, fuel consumption, and additional constraints, such as upper and lower operating limits. In addition, provision must also be made to handle fast load transients, typically with the use of "swing" generators. Furthermore, spinning reserve must also be available to cope with unanticipated load variations. This paper utilizes the Karush-Kuhn-Tucker (KKT) conditions to develop a scheme for economic dispatch of load to generators. The swing generator(s), base load generator upper and lower operating limits, and spinning reserve form constraints on the dispatch algorithm. The goal is to dispatch generators to minimize fuel consumption, while maintaining operating constraints for reliability.

Abstract  A new series of 9,10-diphenytanthracene (DPA)-based blue fluorophores have been synthesized and characterized for organic light-emitting diode (OLED) applications. These fluorophores have a bulky substituent, such as triphenylsilane in TPSDPA and mesitylene in TMPDPA, on the C-2 position. The C-2 substituent also includes electron transporting diphenylphosphine oxide in PPODPA and dimesitylene borane in BMTDPA, or hole transporting N-phenylnaphthalen-1-amine in NPADPA. For TMPDPA blue fluorophores, 9,10-diphenyl substituents of the anthracene core are further attached to hole-transporting 9H-carbazole in CBZDPA and electron-transporting 2-phenyl-1,3,4-oxadiazole in OXDDPA. Absorption and emission spectroscopic properties of all DPA-derived fluorophores, either in solution or in the condensed phase, were fully characterized and the HOMO/LUMO energy levels of these fluorophores were determined. The frontier molecular orbitals of the DPA derivatives were analysed by theoretical methods to determine the possible intramolecular charge transfer (ICT) characteristics. Whereas the blue emission is best preserved in TMPDPA, in which the non-conjugated bulky mesitylene group suppresses red-shifted emissions, the ICT is attributed to the deterioration in the emissions of NPADPA and BMTDPA. In the solid state, PPODPA suffered from red-shifted and weakened emissions because of adverse crystallization, which is promoted by the dipolar nature of the diphenylphosphine oxide substituent. Non-dopant OLEDs were fabricated with DPA, TPSDPA, TMPDPA, PPODPA, CBZDPA, and OXDDPA. Except for PPODPA, the electroluminescence efficiency of these DPA derivatives was significantly improved compared with that of the DPA OLEDs. In particular, CBZDPA and OXDDPA OLEDs exhibited the best external quantum efficiency of 4.5% and 4.0% with a true blue colour, with ClEx,y coordinates of (0.17, 0.17) and (0.16, 0.18), respectively. The improved electroluminescence efficiency can be attributed to the molecular charge transport design of CBZDPA and OXDDPA.

Abstract  Three-dimensional (3D) nanostructures of an endohedral fullerene, Sc3N@C-80 (I-h), including both cubic-shaped and unprecedented dice-shaped crystals, have been successfully prepared for the first time via a modified liquid-liquid interfacial precipitation (LLIP) method integrating ultrasonication. By simply switching ultrasonication on/off upon mixing the good/poor (mesitylene/isopropanol) solvents, the dice- and cubic-shaped Sc3N@C-80 crystals have been selectively prepared, and their size can be readily controlled by varying the concentration of the starting Sc3N@C-80 solution in mesitylene. The growth mechanism of the cubic- and dice-shaped Sc3N@C-80 crystals has been proposed, highlighting the formation of local mesitylene cavities which lead to the nucleation and growth of Sc3N@C-80 molecules, while the formation of the dice structure. i.e., a hole in each facet of the cube, was primarily due to the hindered diffusion of Sc3N@C-80 solutes by ultrasonication-generated gas microbubbles. The crystal structure of the Sc3N@C-80 cubes has been determined as a simple cubic unit cell with a lattice constant of a = 10.8 angstrom. Finally the dice- shaped Sc3N@C-80 crystals were applied as a Pt catalyst support for the methanol oxidation reaction (MOR), revealing the improved MOR activity compared to the cubic-shaped Sc3N@C-80 crystals due to its larger surface area resulting from the dice (hole) structure.

Abstract  Reaction of the acyclic (diamino)carbene (ADC) : C(NiPr2)(2) (1) with different dihaloboranes of the type RBX2 (R = Mes, Dur; X = Cl, Br) smoothly afforded a novel class of ADC-stabilized borane adducts. For MesBBr(2) however, the reaction did not stop at the adduct level, but an uncommon rearrangement process occurred, which eventually resulted in the formation of a 5-membered boracycle after elimination of mesitylene. Chemical reduction of the ADC borane adducts by KC8 selectively yielded air stable 1,2-azaboretidines. Detailed DFT studies suggest a reduction mechanism involving a highly reactive borylene intermediate, which is converted into the boracycles via a rearrangement/C-H activation sequence.

Abstract  Large pore SBA-15 microspheres were synthesized by a simple mesitylene (TMB)-assisted method. A series of characterization results demonstrated that the addition of mesitylene can not only obtain large-pore particles by forming siliceous mesocelluar foam (MCF) structure but facilitate the formation of spherical SBA-15 silicas. It was found that, by the addition of certain amount of TMB, the morphology of SBA-15 silicas is perfectly spherical while the pore structure remains unchanged. And the well-ordered SBA-15 microspheres exhibit large pore and good dispersibility.

Abstract  Hierarchical porous materials especially the silica-based ones are undergoing rapid development due to potential applications in the fields of catalysis, adsorption, separation, and biomedical processes. Although various synthesis methods involving emulsions, colloids, and surfactants have been reported, synthesis of hierarchical porous silicas (HPS) with complex mesophase transformations by using a four-component microemulsion (surfactant/cosurfactant/oil/water) templating approach is still challenging. Herein, we have successfully synthesized porous silica materials by introducing n-butanol (Bu) as the cosurfactant and 1,3,5-trimethylbenzene (TMB) as the oil component in a four-component P123-n-butanol-1,3,5-trimethylbenzene-water system. By simply increasing the molar ratio of Bu to TMB continuously while keeping a fixed mass of TMB in the mean time, mesophase transformations, progressing from mesocellular foam (MCF) via a vesicle-like structure to an ordered 2D hexagonal structure (SBA-15), can be observed. Moreover, an opposite phase transformation process was also proved by gradually increasing the molar ratio of TMB to Bu by maintaining a certain value for the Bu content in the initial system. All the mixed phase silica materials including hexagonal-vesicle, MCF-vesicle-hexagonal, and MCF-disordered-SBA-15-type show hierarchically porous structures. The mechanism for the mesophase transformation was proposed and a micelle/microemulsion method with bimodal templates was put forward to form hierarchical porous silicas with a mixed phase of the MCF-disordered-SBA-15-type structure. Furthermore, a series of Al-containing mesoporous silicas with different structures (hexagonal, vesicle, MCF, MCF-vesicle-hexagonal, and MCF-disordered-SBA-15-type) were used as catalyst supports for dibenzothiophene hydrodesulfurization. The NiMo/Al-hierarchical porous silica catalyst with pore structures of MCF-disordered-SBA-15-type displayed the best hydrodesulfurization performance among all the studied catalysts.

Abstract  Previous research into detonation physics has mostly utilized gaseous fuels such as hydrogen, acetylene, ethylene, and propane. If these fuels were to be used for a pulse detonation engine, they have to be stored under high pressure in steel containers which increase weight safety risks. In order to increase energy density of fuel, liquid fuel was chosen. Tests were conducted on detonation initiation of JP-8/oxygen mixtures at different initial temperatures and equivalence ratios. These tests found a reduction in the rich limit with increasing initial temperature, and the minimum deflagration-to-detonation run-up distance was approximately 200 mm, which was similar to propane/oxygen mixture results. A rapid increase in deflagration-to-detonation run-up distance was observed at equivalence ratios close to the lean and rich limits. Experiments of JP-8/oxygen and propane/oxygen mixtures with nitrogen dilution were also conducted. As the nitrogen/oxygen ratio increased, the lean and rich limits decreased while the detonation wave could not be successfully initiated as the nitrogen-to-oxygen ratio was greater than 0.4.

Abstract  A meso-scale heat recirculating combustor was used to examine the combustion characteristics of two specific synthetic fuels. One of the fuels was made via a Fischer-Tropsch (F-T fuel) process, while the other was produced from tallow (bio-jet fuel). The two fuels were burned in the meso-scale combustor using pure oxygen in a non-premixed injection configuration. The extinction behavior at the fuel-rich and fuel-lean combustion conditions has been investigated for each fuel. The results showed that although the two fuels showed some similarities, the F-T fuel exhibited stable, non-sooting combustion behavior at higher equivalence ratios than the bio-jet fuel. The lean stability limit for the bio-jet fuel was found to be lower (lower equivalence ratio) than that of the F-T fuel. The results were compared with conventional JP-8 jet fuel to provide a comparative analysis of combustion characteristics using the same combustor. A fuel characterization analysis was' performed for each fuel, and their respective thermal efficiencies calculated. The F-T and bio-jet fuels both reached a maximum thermal efficiency of about 95% near their respective rich extinction limits.