13460-50-9Relevant articles and documents
Tuning the structural stability of LiBH4 through boron-based compounds towards superior dehydrogenation
Cai, Weitong,Chen, Juner,Liu, Liying,Yang, Yuanzheng,Wang, Hui
, p. 1171 - 1180 (2018)
The remarkable destabilization effects of H3BO3, HBO2, and B2O3 on dehydrogenation of LiBH4 are revealed in this work. The effectiveness of destabilizing the structural stability is in the order of H3BO3 > HBO2 > B2O3. Besides, through optimizing the molar ratio of LiBH4 and H3BO3 and milling treatment, the destabilization effect, especially for dehydrogenation kinetics, is further enhanced. For example, at a temperature as low as 110 °C, 5.8 wt% hydrogen can be liberated in seconds from 2LiBH4-H3BO3 prepared through pre-milling. The investigation reveals that each of the LiBH4-H3BO3, LiBH4-HBO2 and LiBH4-B2O3 systems undergo multiple dehydrogenation stages corresponding to different destabilization mechanisms. The reaction at lower temperature is ascribed to the H+?H- coupling mechanism which should be enhanced by the [OH]-?[BH4]- interaction mode. Pre-milling treatment of LiBH4 and H3BO3 also promotes the H+?H- interaction which may have originated from the increasing contact area as a result of the fine particles, and therefore probably reduced the reaction activation energy. Consequently, it gives rise to the superior dehydrogenation performance of lower temperature, rapid kinetics, pure hydrogen and high capacity, which are required for off-board hydrogen energy vehicle application.
INFRARED AND RAMAN SPECTRA OF ORTHOROMBIC, MONOCLINIC AND CUBIC METABORIC ACID AND THEIR RELATION TO THE STRENGTH OF THE HYDROGEN BOND PRESENT
Bertoluzza, Alessandro,Monti, Patrizia,Battaglia, Maria Angela,Bonora, Sergio
, p. 123 - 136 (1980)
Infrared and Raman spectra of the three forms of metaboric acid (orthorombic, monoclinic and cubic) are presented and discussed.The behaviour of the asymmetric stretching vibration νOH and of the in-plane and out-of-plane deformations δOH and γOH shows that hydrogen bonds of different strengths are present in the three forms of metaboric acid, in accordance with X-ray diffraction measurements.This phenomenon is explained in a qualitative way by a valence bond treatment of the structural centres present in the three forms of metaboric acid.The remaining vibrational modes are related to the analogous modes present in borates and polyborates of known structure.
Kinetics and Mechanism of Reduction of Hexacyanoferrate(III) by Sodium Tetrahydroborate
Bhattacharjee, Mitra,Bhattacharjee, Apurba K.,Mahanti, Mahendra K.
, p. 3566 - 3569 (1981)
A kinetic investigation of the reduction of hexacyanoferrate(III) by sodium tetrahydroborate in buffered aqueous solution has been carried out.The rate of the reaction is proportional to the concentration of both tetrahydroborate and hydrogen ions.The effect of the addition of some inorganic salts has benn studied.The temperature has been varied, and the Arrhenius parameters have been evaluated.The rate of hydrolysis of tetrahydroborate has been separately studied.It has been observed that the activation energies for both the reactions - the reduction of hexacyanoferrate(III) and the hydrolysis of tetrahydroborate - are equal. a plausible mechanism for the reduction of hexacyanoferrate(III) has been proposed.
Influence of multiphonon and cross relaxations on 3P0 and 1D2 emission levels of Pr3+ doped borosilicate glasses for broad band signal amplification
Naresh,Ham, Byoung S.
, p. 321 - 330 (2016/01/20)
We discuss non-radiative relaxations of visible-near infrared (Vis-NIR) emissions originating from 3P0 and 1D2 levels of Pr3+ glasses. Thermal stability of host lithium aluminium borosilicate (LABS) glass is estimated from thermogravimetric and differential thermal analysis. The structural analysis of host LABS glass through Fourier transform infrared and Raman spectral profiles provide an insight to understand the effect of OH content and phonon energy on luminescence characteristics of Pr3+ ions. Visible emission spectrum of Pr3+ glass is composed of two prominent emission bands at 493 nm (3P0 → 3H4) and 605 nm (1D2 → 3H4) when excited by 448 nm. In NIR region a narrow emission band at 1.06 μm (1D2 → 3F3) and ultra-broad emission band at 1.49 μm (1D2 → 1G4) are observed for 488 nm excitation. For these emission transitions, emission decay curves are measured and analysed. The lifetime shortening due to non-radiative energy transfer is explained by multiphonon interactions and cross-relaxation routes, and later verified by Dexter's model. Electric dipole-dipole mechanism is identified to be responsible for ion-ion interactions intervening in 3P0 and 1D2 states of Pr3+ causing quenching in emission intensities and lifetimes. The large absorption and stimulated emission cross-sections of Pr3+ ions around 1.49 μm suggests suitability of a host material operating for broadband signal amplifications at low-loss optical telecommunication windows. Besides, emission parameters like stimulated emission cross-section (σemi), effective band width (Δλeff) are calculated for 1.49 μm (1D2 → 1G4) of Pr3+ doped silicate based glasses.
Electrospun Cu-doped titania nanofibers for photocatalytic hydrolysis of ammonia borane
Yousef, Ayman,Barakat, Nasser A.M.,Kim, Hak Yong
, p. 98 - 106 (2013/09/02)
Among reported hydrogen storage materials, ammonia borane is a promising candidate to be utilized in many industrial applications. The high chemical resistance of the ceramic catalysts makes them one of the most stable classes of catalytic materials. In this study, CuO nanoparticles (NPs) -doped TiO 2 nanofibers (NFs) are introduced as a highly effective and reusable catalyst for ammonia borane complex hydrolysis. The incorporation of CuO NPs inside the TiO2 NFs provided distinct advantages for the introduced catalyst; the aggregation problem of the CuO NPs was overcome and a synergistic effect was created as the synthesized CuO NPs-doped TiO2 revealed higher activity compared to the individual components. Typically, after 10 min, the obtained hydrogen equivalent was 2.7, 0.9 and 0.95 when CuO NPs-doped TiO2 nanofibers, CuO NPs and pristine TiO2 nanofibers were used as the catalyst, respectively. The catalytic activity of the introduced nanofibers did not change after being used for three successive cycles. Moreover, the catalytic performance was strongly modified when the hydrolysis process was performed under sunlight irradiation because of the photocatalytic activity of the TiO2 and CuO. The introduced nanofibers were prepared by the simple, effective, low cost and high yielding technique of electrospinning. The present study introduces TiO2 nanofibers as a promising catalyst for the ammonia borane complex, as well as an interesting support used for functional materials.
Synthesis of scandium orthoborate powders
Tkachenko,Fedorov,Kuznetsov,Voronov,Lavrishchev,Shukshin,Yarotskaya,Kononova
, p. 171 - 175 (2008/10/09)
Two polymorphs of scandium orthoborate, ScBO3, are synthesized by adding aqueous ammonia to aqueous solutions of scandium nitrate and boric acids and calcining the resulting precipitates. Dehydration of the precipitates reaches completion below
OH-F disorder in non-centrosymmetric Zn2(BO3)(OH)0.75F0.25: Ab initio structure determination and NMR study; Comparison with tridymite and fluoride borates
Corbel,Suard,Emery,Leblanc
, p. 287 - 295 (2008/10/08)
The crystal structure of Zn2(BO3)(OH)0.75F0.25 is determined ab initio from X-ray and neutron powder data. The unit cell is monoclinic, space group P21 (no. 4), Z = 2, with a = 6.8738(4) angstroms, b = 4.9178(2) angstroms, c = 5.7018(3) angstroms, β = 98.829(3) °, V = 190.46(3) angstroms3 (neutron powder data). Alternating up and down ZnO3(OH,F) tetrahedra and triangular BO33- groups built corrugated layers. Their connection by hydroxyl ions gives a 3D network similar to that of tridymite. The statistical distribution of fluorine and hydroxyl in infinite chains is evidenced by magical angle spinning-NMR spectroscopy.
Infrared spectra of molecular B(OH)3 and HOBO in solid argon
Andrews, Lester,Burkholder, Thomas R.
, p. 7203 - 7210 (2007/10/02)
Anhydrous B(OH)3 was pressed into a pellet and sublimed at room temperature under vacuum to give molecular B(OH)3 for argon matrix infrared study.The spectrum showed sharp fundamentals without the effect of hydrogen bonding observed in the solid.Fermi resonances were characterized for two fundamentals.The observed frequencies for B(OH)3 and the three deuterium substituted molecules are in agreement with values from self-consistent field/double zeta plus polarization (SCF/DZP) calculations allowing for appropriate scale factors.The major thermal decomposition products from pulsed laser evaporation of B(OH)3 were H2O, B2O3, and HOBO.Molecular HOBO was characterized by a strong 2020 cm-1 fundamental, which was confirmed by SCF/DZP calculations.
EPOXIDATION OF PROPYLENE BY HYDROGEN PEROXIDE IN ORGANIC SOLVENTS.
Kurylyshin,Shevchuk,Abadzhev,Kozak
, p. 1048 - 1050 (2007/10/02)
The authors report on an experimental study of epoxidation of propylene by hydrogen peroxide in an organic solvent with the use of meta- and orthoboric acids and boric anhydride as catalysts. The products of propylene oxidation were analyzed chromatographically. Hydrogen peroxide was determined in the reaction mixture by the permanganate method. The selectivity of propylene oxide formation, calculated on the amount of hydrogen peroxide reacted, was determined as the molar ratio of propylene oxide formed to hydrogen peroxide consumed. It is shown that increase of the metaboric acid concentration raises the selectivity of propylene oxide formation. The selectivity reaches a high value when the molar content of metaboric acid is approximately equal to the hydrogen peroxide content in the original mixture. Analysis of the precipitate deposited from the reaction mixture showed that it is orthoboric acid. Thus, if the water formed as the result of epoxidation is not removed during the reaction metaboric acid is converted into orthoboric and under the given conditions acts as a coreagent.
