Bimetallic Ru-Ni/TiO2 catalysts for hydrogenation of N-ethylcarbazole:Role of TiO2 crystal structure

Hydrogenation of N-ethylcarbazole(NEC),the hydrogen lean form of a liquid organic hydrogen carrier,on TiO2 supported Ru-Ni bimetallic catalysts is investigated.Crystal structure of TiO2 plays a critical role on the hydrogenation activity and selectivity towards fully hydrogenated product.Ru/anatase catalyst exhibits higher selectivity but lower reactivity compared to Ru/rutile catalyst.Ni addition significantly promotes the performance of Ru/anatase catalyst while causes severe performance deterioration of Ru/rutile catalyst.Commercial P25,a mixture of anatase and rutile phases in approximate ratio A/R1/4,is found to be the best TiO2 support for NEC hydrogenation.Ru/P25 catalyst outperforms both Ru/rutile and Ru/anatase and its activity can be further slightly improved by Ni addition.The unexpected synergism between the two different TiO2 phases for Ru based NEC hydrogenation catalysts is related to metal-support interaction and Ru-Ni interaction.

Liquid organic hydrogen carriers

The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming ＂hydrogen economy＂. The liquid organic hydrogen carriers （LOHCs） with high hydrogen contents, reversibilities and moderate dehydrogenation kinetics have been considered as an alternative option supplementing the extensively investigated inorganic hydride systems. In this review, LOHCs for long distance H2 transport and for onboard application will be discussed with the focuses of the design and development of LOHCs and their hydrogenation ＆ dehydrogenation catalyses.

Au/FeO_x-TiO_2 as an efficient catalyst for the selective hydrogenation of phthalic anhydride to phthalide

Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.

COSMO-RS: An ionic liquid prescreening tool for gas hydrate mitigation

Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial & error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies(E_(HB)) of studied IL inhibitors and comparing the predicted E_(HB) to the depression temperature(?) and induction time. Results show that, predicted EHBand chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately(R = 0.70) with average induction time in literature. It is deduced from the results that, ? increases with increasing IL EHBand/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection.

Effect of micro-clearance structure on the collapse of individual liquid hydrogen bubbles

Cavitation occurs in the micro-clearance of liquid-hydrogen-lubricated bearings owing to the pressure drop caused by high-speed shearing.The pressure undulation caused by cavitation collapse results in bearing surface erosion and significantly affects the bearing performance.In this study,a modified Z-G-B cavitation model was used to study the crushing process of a single liquid hydrogen bubble in a shear micro-clearance.Fast Fourier transform(FFT)and wavelet transform(WT)were applied to study the frequency characteristics of the pressure,mass transfer rate,and vapor mass fraction during bubble rupture in shearing micro-clearance.To obtain a deeper insight into the details of the effect of the shear micro-clearance structure on bubble collapse,the relationship between the flow field energy,attenuation rate,and frequency was investigated.The proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD)methods were used to analyze the energy of each order mode of the flow field.The analysis results of the bubble vibration intensity with respect to time and frequency provide a theoretical basis for the optimization of the bearing structure.

Hydrogen storage by liquid organic hydrogen carriers:Catalyst,renewable carrier,and technology--A review

Hydrogen has attracted widespread attention as a carbon-neutral energy source,but developing efficient and safe hydrogen storage technologies remains a huge challenge.Recently,liquid organic hydrogen carriers(LOHCs)technology has shown great potential for efficient and stable hydrogen storage and transport.This technology allows for safe and economical large-scale transoceanic transportation and long-cycle hydrogen storage.In particular,traditional organic hydrogen storage liquids are derived from nonrenewable fossil fuels through costly refining procedures,resulting in unavoidable environmental contamination.Biomass holds great promise for the preparation of LOHCs due to its unique carbon-balance properties and feasibility to manufacture aromatic and nitrogen-doped compounds.According to recent studies,almost 100%conversion and 92% yield of benzene could be obtained through advanced biomass conversion technologies,showing great potential in preparing biomass-based LOHCs.Overall,the present LOHCs systems and their unique applications are introduced in this review,and the technical paths are summarized.Furthermore,this paper provides an outlook on the future development of LOHCs technology,focusing on biomass-derived aromatic and N-doped compounds and their applications in hydrogen storage.

A novel cryogenic insulation system of hollow glass microspheres and self-evaporation vapor-cooled shield for liquid hydrogen storage

Liquid hydrogen(LH2)attracts widespread attention because of its highest energy storage density.However,evaporation loss is a serious problem in LH2 storage due to the low boiling point(20 K).Efficient insulation technology is an important issue in the study of LH2 storage.Hollow glass microspheres(HGMs)is a potential promising thermal insulation material because of its low apparent thermal conductivity,fast installation(Compared with multi-layer insulation,it can be injected in a short time.),and easy maintenance.A novel cryogenic insulation system consisting of HGMs and a selfevaporating vapor-cooled shield(VCS)is proposed for storage of LH2.A thermodynamic model has been established to analyze the coupled heat transfer characteristics of HGMs and VCS in the composite insulation system.The results show that the combination of HGMs and VCS can effectively reduce heat flux into the LH2 tank.With the increase of VCS number from 1 to 3,the minimum heat flux through HGMs decreases by 57.36%,65.29%,and 68.21%,respectively.Another significant advantage of HGMs is that their thermal insulation properties are not sensitive to ambient vacuum change.When ambient vacuum rises from 10^-3 Pa to 1 Pa,the heat flux into the LH2 tank increases by approximately 20%.When the vacuum rises from 10^-3 Pa to 100 Pa,the combination of VCS and HGMs reduces the heat flux into the tank by 58.08%-69.84% compared with pure HGMs.

Prospects of sea launches for Chinese cryogenic liquid-fueled medium-lift launch vehicles

This paper introduces the sea-launch technology of a cryogenic liquid-fueled medium-lift rocket.It first reviews the current state of sea launch technology,and then gives a brief introduction of China’s New Generation Medium-lift Launch Vehicle(NGMLV).The innovations in the NGMVL,such as responsive test and launch control,a H3 launch model,and unmanned operations,provide convenience for sea launches.Based on these innovations,this paper proposes a sea launch scheme,including the system configuration,test and launch processes,and an improved adaptive design for the rocket.Then,the launch platform is discussed in detail,which integrates the functions of sea transportation,assembly and test,as well as technical and launch areas.The layout and function divisions,fluid filling,gas supply and distribution systems,and lossless storage technology of LH2 are described in order.This breakthrough in sea launch technology will enable China to launch medium and large satellites and constellations‘both on land and sea’,especially into low-inclination Low-Earth Orbits(LEOs),and it allows China to remain competitive in the fast-paced space industry.

Flow-induced vibration characteristics of the U-type Coriolis mass flowmeter with liquid hydrogen

Compared with liquid nitrogen(LN_(2))and water,the density of liquid hydrogen(LH_(2))is more than one order of magnitude smaller,which leads to significantly different flow-induced vibration characteristics in the coriolis mass flowmeter(CMF).Based on the Euler beam theory,the complex set of equations of fluid-solid interactions for the U-type pipe Coriolis flowmeter with LH_(2)is solved.The calculation results are firstly validated by comparing the dimensionless frequency,displacement,and twist mode shape with the theoretical and experimental results in the other publications with water and kerosene as the working fluids.Then,the results of dimensionless frequency,phase difference,and time lag for LH_(2)are compared with those for LN_(2)and water,and the effects of the dimensionless flow velocity,sensor position,and the radius of the curved pipe are analyzed in detail for LH_(2).Results show that the time lag of LH_(2)is an order of magnitude smaller than that for LN_(2)or water.The excitation frequency for LH_(2)is much larger than that for LN_(2).Effects of geometric parameters on the time lag are also analyzed for the three fluids and the results contribute to the design optimization of a CMF for LH_(2).

Nonstoichiometric Yttrium Hydride–Promoted Reversible Hydrogen Storage in a Liquid Organic Hydrogen Carrier

N-Ethylcarbazole(NEC)is one of the most promising liquid organic hydrogen carriers(LOHCs),but its application is limited by sluggish kinetics due to lack of high-efficiency,low-cost catalysts.This work reports a cobalt(Co)-based catalyst promoted by nonstoichiometric yttrium hydride(YH_(3−x))to achieve high-efficiency,reversible hydrogen storage in NEC,with>5.5 wt%reversible hydrogen storage capacity could be achieved below 473 K,and with good kinetics.The YH_(3−x)-promoted Co-based catalyst is the first non-noble metal catalyst with high activity for NEC hydrogenation and 12H-NEC dehydrogenation reactions.A mechanistic study suggests that YH_(3−x)facilitates the reversible hydrogen transfer both in the hydrogenation and the dehydrogenation reactions.The nonstoichiometric YH_(3−x)contained both lattice H and H vacancies with tunable H chemical potential serve as the H donor and H acceptor for reversible hydrogen transfer.Our results support the practical application of LOHCs and inspire new approaches for the utilization of conventional metal hydrides to promote versatile H transfer reactions.

Hydrogen bonding mediated ion pairs of some aprotic ionic liquids and their structural transition in aqueous solution

Ion pair speciation of ionic liquids(ILs) has an important effect on the physical and chemical properties of ILs and recognition of the structure of ion pairs in solution is essential. It has been reported that ion pairs of some ILs can be formed by hydrogen bonding interactions between cations and anions of them. Considering the fact that far-IR(FIR) spectroscopy is a powerful tool in indicating the intermolecular and intramolecular hydrogen bonding, in this work, this spectroscopic technique has been combined with molecular dynamic(MD) simulation and nuclear magnetic resonance hydrogen spectroscopy(~1H NMR) to investigate ion pairs of aprotic ILs [Bmim][NO_3], [BuPy][NO_3], [Pyr_(14)][NO_3], [PP_(14)][NO_3] and [Bu-choline][NO_3] in aqueous IL mixtures. The FIR spectra have been assigned with the aid of density functional theory(DFT) calculations, and the results are used to understand the effect of cationic nature on the structure of ion pairs. It is found that contact ion pairs formed in the neat aprotic ILs by hydrogen bonding interactions between cation and anion, were still maintained in aqueous solutions up to high water mole fraction(say 0.80 for [BuPy][NO3]). When water content was increased to a critical mole fraction of water(say 0.83 for [BuPy][NO3]), the contact ion pairs could be transformed into solvent-separated ion pairs due to the formation of the hydrogen bonding between ions and water. With the further dilution of the aqueous ILs solution, the solvent-separated ion pairs was finally turned into free cations and free anions(fully hydrated cations or anions). The concentrations of the ILs at which the contact ion pairs were transformed into solvent-separated ion pairs and solvent-separated ion pairs were transformed into free ions(fully hydrated ion) were dependent on the cationic structures. These information provides direct spectral evidence for ion pair structures of the aprotic ILs in aqueous solution. MD simulation and ~1H NMR results support the conclusion drawn from FIR spectra investigations.

Ultrasonic attenuation investigation of liquid hydrogen

Ultrasonic attenuation in liquid hydrogen has been messured with the pulse-echo technique as a function of temperature from 13.84K to 20.50K, at 45MHz . The results indicate that the temperature dependence of ultrasonic attenuation in liquid hydrogen is mainly determined by volume viscosity effect. Ultrasonic attenuatin due to volume viscosity is getting more and more with cooling. The ratio between volume viscous coefficient and shear viscous coefficient is from 1.4 to 4.2 within the measured temperature region.

Rapid proton diffusion in hydroxyl functionalized imidazolium ionic liquids

There is considerable interest in using ionic liquids(ILs) as protic electrolytes. However, the reported proton transfer rate in ILs is quite slow. In this study, we report functionalizing imidazolium ILs with alcohol hydroxyls, aiming at constructing hydrogen bonding networks in the electrolyte, can stimulate fast proton hopping transfer. For demonstration, the diffusion of proton and Cl. in 1-(3-hydroxypropyl)-3-methylimidazolium tetrafluoroboride(C_3OHmimBF_4) were studied using cyclic voltammetry and potentiostatic method at 30 °C. The diffusion coefficient of proton is about one order of magnitude higher than that of Cl. in the same electrolyte, and about 5 times that of proton in the non-hydydroxyl 1-(butyl)-3-methylimidazolium tetrafluoroboride(BmimBF_4) when normalized to the diffusion coefficients of Cl. in respective ILs. In the meantime, 1H NMR spectra revealed a strong hydrogen bonding interaction between proton and C_3OHmimBF_4 which is absent between proton and BmimBF_4, thus the significantly higher diffusion coefficient of proton in C_3OHmimBF_4 may suggest the formation of effective hydrogen bonding networks, enabling rapid proton hopping via the Grotthuss mechanism.

Highly efficient hydrogen production from methanol by single nickel atoms anchored on defective boron nitride nanosheet

Exploiting inexpensive and effective nickel-based catalysts that produce hydrogen from liquid organic hydrogen carriers(LOHCs)is crucial to alleviating the global energy and environmental crisis.In this study,we report a rational strategy that can realize atomically dispersed Ni atoms anchored on vacancy-abundant boron nitride nanosheets(Ni1/h-BNNS)with high specific surface area(up to 622 m^(2)·g^(-1))and abundant hydroxyl groups for high efficient hydrogen production.Methanol dehydrogenation results show an excellent hydrogen production performance catalyzed by this Ni1/h-BNNS,as evidenced by a remarkably high H_(2) yield rate(1684.23 mol·mol_(Ni)^(-1)·h^(-1)),nearly 100%selectivity toward hydrogen and CO,and high anti-coking performance.Density functional theory(DFT)calculations reveal that the outstanding catalytic performance of Ni1/h-BNNS primarily originates from the unique coordinated environment of atomically dispersed Ni(Ni-B_(2)O_(2))and the synergistic interaction between Ni single atoms and the h-BNNS support.Specifically,the coordinated O atoms play a decisive role in promoting the activity of Ni,and the neighboring B sites significantly decrease the energy barriers for the adsorption of key intermediates of methanol dehydrogenation.This study offers a novel strategy for developing high-performance and stable single-atom Ni catalysts by precisely controlling single-atom sites on h-BN support for sustainable hydrogen production.

Microscopic study of binary mixtures between pyrrolidinium bis(triflorosulfonyl)imide and dimethyl sulfoxide/acetonitrile

Molecular interactions of a representative pyrrolidinium-based ionic liquid 1-butyl-l-methyl-pyrrolidinium bis（triflorosulfonyl）- imide （[BMPyrr][TFSI]） with dimethyl sulfoxide （DMSO） and acetonitrile （AN） have been analyzed in this work. Attenuated total reflection Fourier transform infrared spectroscopy （ATR-FTIR） and density functional theory （DFT） calculations are used in the investigation, while excess infrared spectra and two-dimensional correlation spectroscopy are used to explore the data in detail. It has been found that the molecular solvents can interact with TFSI- （mainly with S=O and weakly with S-N-S group）. AN interacts feebly with BMPyrr＋ as compared with the strong interaction of DMSO. The strength of the interactions depends on the electron donating ability of the solvent. Upon mixing, hydrogen bonds regarding C-Hs in cation and S-N-S in anion are weakened, while that regarding S=O in anion is strengthened. Among the C-Hs which are connected directly with the N of the cation, Cl-H is the main interaction site for both DMSO and AN. This means that Cl-H is the most acidic hydrogen in pyrrolidinium cation.

Study on critical technologies and development routes of coal-based hydrogen energy

Hydrogen is considered a secondary source of energy,commonly referred to as an energy carrier.It has the highest energy content when compared to other common fuels by weight,having great potential for further development.Hydrogen can be produced from various domestic resources but,based on the fossil resource conditions in China,coal-based hydrogen energy is considered to be the most valuable,because it is not only an effective way to develop clean energy,but also a proactive exploration of the clean usage of traditional coal resources.In this article,the sorption-enhanced water-gas shift technology in the coal-to-hydrogen section and the hydrogen-storage and transport technology with liquid aromatics are introduced and basic mechanisms,technical advantages,latest progress and future R&D focuses of hydrogen-production and storage processes are listed and discussed.As a conclusion,after considering the development frame and the business characteristics of CHN Energy Group,a conceptual architecture for developing coal-based hydrogen energy and the corresponding supply chain,is proposed.