Deep Hydrogenation Research Articles

Effect of deep eutectic solvents hydrogen bond acceptor on the anhydrous proton conductivity of Nafion membrane for fuel cell applications

This study intended to assess the role of halogens on proton conductivity of polymer electrolyte membranes (PEMs) for fuel cell applications. For this purpose, the halogens were used as hydrogen bond acceptors (HBA) to form deep eutectic solvents (DES) which were later used as electrolyte in Nafion membrane. The prepared DESs were initially characterized in terms of rheology, thermal behavior, and ionic conductivity. Then, Nafion/DES composite membranes were prepared and their electrochemical reactions, thermal stabilities and proton conductivities were characterized. Interestingly, the bromide containing DESs provided super proton conductivity in Nafion/DES composites so that a proton conductivity of 337 mS/cm was achieved at 100 °Cat anhydrous condition which was about 120% higher than the iodide based Nafion/DES membranes and about 1200 % higher than other Nafion/ionic liquid PEMs at anhydrous condition. An upper bound concept was introduced for the Nafion/DES composite membranes which was compared with those obtained for conventional Nafion/ionic liquid composite membranes at anhydrous conditions. Furthermore, fuel cell performance of Nafion/DES composite membrane showed that DESs can be considered as proper electrolytes for anhydrous PEMs, and their properties can be justified by halogen type.

Effect of the ruthenium deposition method on the nanostructured catalyst activity in the deep hydrogenation of benzene

Ru-containing catalysts supported on halloysite aluminosilicate nanotubes (HNTs) were prepared by incipient wetness impregnation, vacuum impregnation, and impregnation under the microwave irradiation methods. Composition and structure of the catalysts were determined by X-ray fluorescence (XRF), thermo-programmed reduction (TPR-H2), and transmission electron microscopy (TEM). Textural characteristics were detected by low-temperature nitrogen adsorption—desorption. The activity of the catalysts was investigated in benzene hydrogenation at 80°?, a hydrogen pressure of 3.0 MPa, and a molar ratio of benzene to Ru of 2000. It was found that Ru nanoparticles prepared by vacuum impregnation are deposited mainly into the internal cavity of aluminosilicate nanotubes, while in samples obtained by wetness impregnation the active phase is formed predominantly on the external surface of halloysite. The catalyst prepared by impregnation under microwave irradiation is characterized by a high Ru content, its uniformly distributed metal particles are located mainly on the external surface of HNT, and it demonstrated the superior activity in hydrogenation of benzene to cyclohexane.

Manufacturing of Coal-Based Synthetic Jet Fuels Interchangeable with JET A-1 and T-8B Petroleum Fuels

A scheme for the combined processing of coal to produce synthetic jet fuel is proposed and experimentally verified. It has been established that using an approach including coal coking followed by gasification, Fischer–Tropsch synthesis, and hydroisomerization, the resulting kerosene fractions are characterized by low density values (0.741–0.751 kg/dm3 at 20°С) relative to the level specified by the technical requirements for Jet A-1 and T-8B jet fuel brands used today. With the use of the hydroisomerization process (Т = 330–345°С, pH2 = 72 bar) in the presence of a 2% Pt/Al-HMS (10) catalyst, it has been possible to obtain an isoparaffin fraction with the crystallization temperature below −56°С. The coal tar produced by coking of coal was subjected to deep hydrogenation to obtain a naphthenic jet fuel component characterized by the boiling range of 150–250°С, a density of about 0.873 kg/dm3 (20°С), and low sulfur and aromatics contents (3 ppm and 23 wt %, respectively). By compounding the isoparaffin and naphthenic fractions produced, experimental samples of synthetic jet fuels have been obtained that meet the technical requirements for Jet A-1 and T-8B fuels.

Manganese Oxide Modified Nickel Catalysts for Photothermal CO Hydrogenation to Light Olefins

AbstractNi‐based catalysts are traditionally considered unsuitable for the Fischer–Tropsch syntheses of olefins, due to the very strong hydrogenation ability of metallic Ni. Herein, this paradigm is challenged. A series of MnO supports nickel catalysts (denoted herein as Ni‐x) are fabricated by H2 reduction of a nickel‐manganese mixed metal oxide at temperatures (x) ranging from 250 to 600 °C. The Ni‐500 catalyst displays unprecedented performance for photothermal CO hydrogenation to olefins, with an olefin selectivity of 33.0% under ultraviolet–visible irradiation. High‐resolution transmission electron microscopy, X‐ray absorption spectroscopy (XAS), and X‐ray diffraction analyses reveal that the Ni‐x catalysts contain metallic Ni nanoparticles supported by MnO. X‐ray photoelectron spectroscopy and XAS establish that electron transfer from MnO to the Ni0 nanoparticles is responsible for modifying the electronic structure of nickel (creating Niδ− states), thereby shifting the CO hydrogenation selectivity toward light olefins. Further, density functional theory calculations show that this electron transfer lowers the adsorption energies of olefins on Ni surfaces, thus minimizing the undesirable deep hydrogenation reactions to higher alkanes. This study conclusively demonstrates that MnO‐modified Ni‐based catalyst systems can be highly selective for CO hydrogenation to light olefins.

Impact of deep hydrogenation on jet fuel oxidation and deposition

Thermal oxidative stability is a key issue for jet fuel serving as a coolant of high-performance aircraft. This study investigated the effects of the hydrogenation degree on the oxidation and deposition of jet fuel (RP-3). Fuels with different hydrogenation degrees were achieved by a commercial catalyst, with the aromatic content reduced from 12.6 wt% to 0.4 wt%, resulting in a slight density decrease and a slight increase of the net heating value. Meanwhile, the total sulfur content of hydrogenated fuel was lowered to below 1 ppm, and the naturally occurring phenols were completely removed. The initial oxidation reactivity and deposition tendency of hydrogenated fuels were investigated by pressure differential scanning calorimetry and jet fuel thermal oxidation tester, respectively. For the initial oxidation, both the oxidation OT (onset temperature) and IP (induction period) of jet fuel decrease with increasing hydrogenation degree and show good linear correlations with the aromatic content. For thermal deposition, pristine RP-3 cannot pass the JFTOT test (355 °C for 5 h), while all hydrogenated RP-3-t can pass 355 °C JFTOT test, owing to the almost total removal of inherent heteroatomic species (sulfurs and phenols) by hydrogenation. This work confirms that deep hydrogenation is a promising approach to improve the thermal oxidative stability of jet fuel (fewer deposits) for the practical applications.

Presolidification Changes in the Structural–Dynamic Characteristics of Glass-Forming Metallic Melts during Deep Cooling, Vitrification, and Hydrogenation

The amorphization and solidification of binary and multicomponent transition-metal-based melts are considered. The presolidification structural changes and the atomic dynamics in metallic melts and other liquid substances that occur during forced quenching and deep supercooling are analyzed and compared as functions of their composition, the atomic size, the character of interatomic bonds, and the presence of eutectics and compounds in phase diagrams. The hydrogenation of a melt changes presolidification processes, affecting the atomic configuration, the modulation of a frequency spectrum, and the fluctuations of band structure (which determines the character of vitrification).

An industrially feasible pathway for preparation of Mo nanopowder and its sintering behavior

In this study, a low-cost, efficient and industrially feasible pathway was developed to prepare Mo nanopowder via a two-stage carbothermic reduction of commercial MoO3 with carbon black at 600 °C and 1050 °C, respectively, followed by deep hydrogen reduction at 800 °C. The sintering behaviors of the prepared Mo nanopowder and micron commercial Mo powder containing different amounts of Mo nanopowder were investigated in the temperature range of 1000 °C–1600 °C. At 1200 °C, the Mo nanopowder was sintered to near-fully densified compact with a relative density of about 95.8%, which was much higher than the value of 70% for commercial Mo powder. For the nanopowder, the grain size dramatically increased when the sintering temperature increased. The hardness of sintered nanopowder at 1200 °C (relative density, 95.8%; average grain size, 1.88 μm) was about 254 HV0.1, which was much higher than the value of 182 HV0.1 as sintering commercial micron sized Mo at 1600 °C (relative density, 93.9%). The addition of Mo nanopowder into micron Mo can noticeably activate its sintering and improve its hardness.

Bayesian cosmic density field inference from redshift space dark matter maps.

We present a self-consistent Bayesian formalism to sample the primordial density fields compatible with a set of dark matter density tracers after a cosmic evolution observed in redshift space. Previous works on density reconstruction did not self-consistently consider redshift space distortions or included an additional iterative distortion correction step. We present here the analytic solution of coherent flows within a Hamiltonian Monte Carlo posterior sampling of the primordial density field. We test our method within the Zel'dovich approximation, presenting also an analytic solution including tidal fields and spherical collapse on small scales. Our resulting reconstructed fields are isotropic and their power spectra are unbiased compared to the true field defined by our mock observations. Novel algorithmic implementations are introduced regarding the mass assignment kernels when defining the dark matter density field and optimization of the time-step in the Hamiltonian equations of motions. Our algorithm, dubbed barcode, promises to be specially suited for analysis of the dark matter cosmic web down to scales of a few megaparsecs. This large-scale structure is implied by the observed spatial distribution of galaxy clusters - such as obtained from X-ray, Sunyaev-Zel'dovich, or weak lensing surveys - as well as that of the intergalactic medium sampled by the Ly α forest or perhaps even by deep hydrogen intensity mapping. In these cases, virialized motions are negligible, and the tracers cannot be modelled as point-like objects. It could be used in all of these contexts as a baryon acoustic oscillation reconstruction algorithm.

Theoretical Study of the Structure and Stability of Layerwise Hydrogenated Aluminum Clusters Al44Hn and Al89Hm

Structural parameters, energies, and spectroscopic characteristics of two series of layerwise hydrogenated aluminum clusters Al44Hn (n = 27–44) and Al89Hm (m = 15, 24, 39, and 63) have been calculated by the density functional theory method. It has been shown that increasing number of H atoms in both series entails rapid enhancement of structural distortions up to cooperative rearrangements accompanied by a change in the shape and composition of the surface layer and internal core of the cluster. At the end of the first series Al44Hn, several surface atoms migrate to the outer sphere of the cage to form valence-unsaturated “outer-surface” AlHn and Al2Hn moieties, which can be active sites at the stages of deeper hydrogenation. Simultaneously, the inner core [Al]5 disintegrates, and its atoms are introduced into the surface layer. A family of “inverted” Al42H42 isomers with the hollow [Al42] cage has been localized; the isomers contain the endohedral AlH4 group and “inner” Al-H bonds with their hydrogen end directed to the center of the inner cavity. At the end of the second series, five alanate groups AlH4 and two Al3H2 fragments bonded to the surface through hydrogen bridges are formed in the outer sphere of the $$\rm{Al}_{89}H_{63}^-$$ cluster. The results are of interest for DFT modeling of hydrogenation of nanosized aluminum clusters at the molecular level.

Product Selectivity Controlled by Nanoporous Environments in Zeolite Crystals Enveloping Rhodium Nanoparticle Catalysts for CO2 Hydrogenation.

Supported rhodium nanoparticles (NPs) are well-known for catalyzing methanation in CO2 hydrogenation. Now we demonstrate that the selectivity in this process can be optimized for CO production by choice of molecular sieve crystals as supports. The NPs are enveloped within the crystals with controlled nanopore environments that allow tuning of the catalytic selectivity to minimize methanation and favor the reverse water-gas shift reaction. Pure silica MFI (S-1)-fixed rhodium NPs exhibited maximized CO selectivity at high CO2 conversions, whereas aluminosilicate MFI zeolite-supported rhodium NPs displayed high methane selectivity under the equivalent conditions. Strong correlations were observed between the nanoporous environment and catalytic selectivity, indicating that S-1 minimizes hydrogen spillover and favors fast desorption of CO to limit deep hydrogenation. Materials in this class appear to offer appealing opportunities for tailoring selective supported catalysts for a variety of reactions.

Research on HLCO entering the secondary riser of FDFCC unit to improve light aromatics production

In the context of prolific chemical raw materials, the flexible dual-riser fluid catalytic cracking (FDFCC) was put forward to increase the yield of light aromatics, in which hydrofining light cycle oil (HLCO) was processed in the second riser under high temperature. The process not only meets the increasing demand for aromatics, but also solves the problem of high aromatics content (more than 50 wt%) of FCC gasoline, which is difficult to meet increasingly stringent gasoline standards. The results of the pilot experiment showed that the optimization reaction temperature of the secondary riser of the FDFCC unit was 575 °C, and the content of aromatics in cracked gasoline reached 78 wt% or more. It should be noted that light cycle oil (LCO) should be subjected to deep hydrogenation from the perspective of increasing aromatics production.

Process Simulation and Economic Evaluation of Bio-Oil Two-Stage Hydrogenation Production

Bio-oil hydrogenation upgrading process is a method that can convert crude bio-oil into high-quality bio-fuel oil, which includes two stages of mild and deep hydrogenation. However, coking in the hydrogenation process is the key issue which negatively affects the catalyst activity and consequently the degree of hydrogenation in both stages. In this paper, an Aspen Plus process simulation model was developed for the two-stage bio-oil hydrogenation demonstration plant which was used to evaluate the effect of catalyst coking on the bio-oil upgrading process and the economic performance of the process. The model was also used to investigate the effect of catalyst deactivation caused by coke deposition in the mild stage. Three reaction temperatures in the mild stage (250 °C, 280 °C, and 300 °C) were considered. The simulation results show that 45% yield of final product is obtained at the optimal reaction condition which is 280 °C for the mild stage and 400 °C for the deep stage. Economic analysis shows that the capital cost of industrial production is $15.2 million for a bio-oil upgrading plant at a scale of 107 thousand tons per year. The operating costs are predicted to be $1024.27 per ton of final product.

Large diamond education mechanism

The article shows the conditions for the formation and existence of both polymorphic modifications of carbon in natural conditions The formation of diamond and carbon can be realized in the presence of carbon containing rocks in near surface and surface reducing conditions with a low partial pressure of oxygen The formation of explosion tubes is carried out due to a chain reaction between deep hydrogen and oxygen in the air with the release of a huge amount of heat increasing the temperature to deg C during a typical exothermic reaction

Supported Polymetallic Catalysts by Self-Propagating Surface Synthesis

Supported polymetallic catalysts (5–15% wt% of active phase) for deep oxidation and hydrogenation were successfully prepared by Self-propagating Surface Synthesis (SSS) using metal nitrates as oxidants and urea as a fuel. Commercial granules of γ-Al2O3; NaA, NaX, ZSM-5 zeolites; and silica gel were used as supports. The synthesized catalysts were characterized by XRD, BET, and SEM/EDS. Catalytic behavior of the catalysts in a flow reactor was determined by gas–liquid chromatography, chemical analysis, and tested in deep oxidation of CO and propane as well as in hydrogenation of CO2 to methane.

Synthesis of a Ni Phyllosilicate with Controlled Morphology for Deep Hydrogenation of Polycyclic Aromatic Hydrocarbons

Deep hydrogenation of polycyclic aromatic hydrocarbons is an important reaction in the petroleum industry. Sintering and coking of active metal nanoparticles are major reasons for deactivation. In this study, a Ni phyllosilicate with different morphologies was synthesized by a modified hydrothermal method and used in the hydrogenation of naphthalene. The physicochemical properties of the Ni phyllosilicate were carefully examined by various characterizations. The in situ exsolution of Ni nanoparticles inlaid into Ni phyllosilicate strengthens the interaction between nanoparticles and support, thereby maintaining the size of the Ni nanoparticles during the reaction. The surface Lewis acid sites of the Ni phyllosilicate are beneficial for the adsorption of aromatic substrates and favor the deep hydrogenation of polycyclic aromatic hydrocarbons under optimal reaction conditions. Besides, the pore size distribution of the Ni phyllosilicate may have a profound effect on its performance stability. The Ni phyllos...

A GBT Survey of the HALOGAS Galaxies and Their Environments. I. Revealing the Full Extent of H i around NGC 891, NGC 925, NGC 4414, and NGC 4565

Abstract We present initial results from a deep neutral hydrogen (H i) survey of the HALOGAS galaxy sample, which includes the spiral galaxies NGC 891, NGC 925, NGC 4414, and NGC 4565, performed with the Robert C. Byrd Green Bank Telescope (GBT). The resulting observations cover at least 4 deg2 around these galaxies, with an average 5σ detection limit of 1.2 × 1018 cm−2 over a velocity range of 20 km s−1 and angular scale of 9.′1. In addition to detecting the same total flux as the GBT data, the spatial distribution of the GBT and original Westerbork Synthesis Radio Telescope data match well at equal spatial resolutions. The H i mass fraction below H i column densities of 1019 cm−2 is, on average, 2%. We discuss the possible origins of low column density H i of nearby spiral galaxies. The absence of a considerable amount of newly detected H i by the GBT indicates these galaxies do not have significant extended diffuse H i structures, and suggests future surveys planned with the SKA and its precursors must go at least as deep as 1017 cm−2 in column density to significantly increase the probability of detecting H i associated with the cosmic web and/or cold mode accretion.

Deep neutral hydrogen observations of Leo T with the Westerbork Synthesis Radio Telescope

Leo T is the lowest mass gas-rich galaxy currently known and studies of its gas content help us understand how such marginal galaxies survive and form stars. We present deep neutral hydrogen (H I) observations from the Westerbork Synthesis Radio Telescope in order to understand its H I distribution and potential for star formation. We find a larger H I line flux than the previously accepted value, resulting in a 50% larger H I mass of 4.1 × 105 M⊙. The additional H I flux is from low surface brightness emission that was previously missed; with careful masking this emission can be recovered even in shallower data. We perform a Gaussian spectral decomposition to find a cool neutral medium component (CNM) with a mass of 3.7 × 104 M⊙, or almost 10% of the total H I mass. Leo T has no H I emission extending from the main H I body, but there is evidence of interaction with the Milky Way circumgalactic medium in both a potential truncation of the H I body and the offset of the peak H I distribution from the optical center. The CNM component of Leo T is large when compared to other dwarf galaxies, even though Leo T is not currently forming stars and has a lower star formation efficiency than other gas-rich dwarf galaxies. However, the H I column density associated with the CNM component in Leo T is low. One possible explanation is the large CNM component is not related to star formation potential but rather a recent, transient phenomenon related to the interaction of Leo T with the Milky Way circumgalactic medium.

Thiol Treatment Creates Selective Palladium Catalysts for Semihydrogenation of Internal Alkynes

Summary Surface and interfacial engineering of heterogeneous metal catalysts is effective and critical for optimizing selective hydrogenation for fine chemicals. By using thiol-treated ultrathin Pd nanosheets as a model catalyst, we demonstrate the development of stable, efficient, and selective Pd catalysts for semihydrogenation of internal alkynes. In the hydrogenation of 1-phenyl-1-propyne, the thiol-treated Pd nanosheets exhibited excellent catalytic selectivity (>97%) toward the semihydrogenation product (1-phenyl-1-propene). The catalyst was highly stable and showed no obvious decay in either activity or selectivity for over ten cycles. Systematic studies demonstrated that a unique Pd-sulfide/thiolate interface created by the thiol treatment was crucial to the semihydrogenation. The high catalytic selectivity and activity benefited from the combined steric and electronic effects that inhibited the deeper hydrogenation of C=C bonds. More importantly, this thiol treatment strategy is applicable to creating highly active and selective practical catalysts from commercial Pd/C catalysts for semihydrogenation of internal alkynes.

CO2-induced destabilization of pyrite-structured FeO2Hx in the lower mantle

Abstract Volatiles, such as carbon and water, modulate the Earth's mantle rheology, partial melting and redox state, thereby playing a crucial role in the Earth's internal dynamics. We experimentally show the transformation of goethite FeOOH in the presence of CO2 into a tetrahedral carbonate phase, Fe4C3O12, at conditions above 107 GPa—2300 K. At temperatures below 2300 K, no interactions are evidenced between goethite and CO2, and instead a pyrite-structured FeO2Hx is formed as recently reported by Hu et al. (2016; 2017) and Nishi et al. (2017). The interpretation is that, above a critical temperature, FeO2Hx reacts with CO2 and H2, yielding Fe4C3O12 and H2O. Our findings provide strong support for the stability of carbon-oxygen-bearing phases at lower-mantle conditions. In both subducting slabs and lower-mantle lithologies, the tetrahedral carbonate Fe4C3O12 would replace the pyrite-structured FeO2Hx through carbonation of these phases. This reaction provides a new mechanism for hydrogen release as H2O within the deep lower mantle. Our study shows that the deep carbon and hydrogen cycles may be more complex than previously thought, as they strongly depend on the control exerted by local mineralogical and chemical environments on the CO2 and H2 thermodynamic activities.

Electrical isolation of GaAs and AlGaAs/GaAs Quantum Cascade Lasers by deep hydrogen implantation

Ion implantation can be applied to form the electrical isolation in AlGaAs/GaAs Quantum Cascade Laser (QCL) instead of mesa etching. In this paper, we present in detail the designing of hydrogen implant isolation scheme, alongside with its verification and study of thermal stability by structural and electrical characterization techniques. Our scheme employed 4µm thick metallic mask made mainly of gold which also served as contact layer, and 640keV hydrogen implantation to a fluency of 1 × 1015cm−2. We obtained the sheet resistivity RSH of (1.5 ± 0.9) × 109Ω/□. The critical temperature for the hydrogen implant isolation fabrication of the AlGaAs/GaAs QCL was determined to be 310℃. Defect density dropped to residual levels after 1min annealing at 300℃ and 400℃, while the material was still resistive with RSH above 108Ω/□. Based on our simulated vacancy maps we concluded that the minimum width of the masking structure should be at least 5µm to avoid the effects of lateral isolation for the given implantation conditions. The QCL device fabricated with this isolation scheme operated with threshold current densities of 6kA/cm2 at the temperature of 77K. Ultimately, we confirmed the applicability of hydrogen implant isolation for the manufacturing of optical devices.