scholarly journals The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al Derived from AlH3

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 559 ◽  
Author(s):  
Qing He ◽  
Dongdong Zhu ◽  
Xiaocheng Wu ◽  
Duo Dong ◽  
Xiaoying Jiang ◽  
...  
Keyword(s):  
Reaction Products ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Scanning Calorimetry ◽  
Mass Spectral Analysis ◽  
X Ray ◽  
Mass Spectral ◽  
Al Composite ◽  
Dehydrogenation Mechanism

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by as-derived Al (denoted Al*) from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H” + B2H6 + H2; (2) the decomposition of “Li-Al-B-H” compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; and (5) LiH + Al → LiAl + 1/2H2. Furthermore, the reversibility of the LiBH4/Al* composite is based on the following reaction: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of the dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2, and LiAl) on the surface of Al*. A passivation shell formed by these products on the Al* is the kinetic barrier to the dehydrogenation of the LiBH4/Al* composite.

scholarly journals The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al* Derived from AlH3

2019 ◽  
Author(s):  
Qing He ◽  
Dongdong Zhu ◽  
Xiaocheng Wu ◽  
Duo Dong ◽  
Xiaoying Jiang ◽  
...  
Keyword(s):  
Reaction Products ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Scanning Calorimetry ◽  
Mass Spectral Analysis ◽  
X Ray ◽  
Mass Spectral ◽  
Al Composite ◽  
Dehydrogenation Mechanism

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by active Al* derived from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H” + B2H6 + H2; (2) the decomposition of "Li-Al-B-H" compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; (5) LiH + Al → LiAl + 1/2H2. And the reversibility of LiBH4/Al* composite is based on equation as follows: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2 and LiAl, etc.) on the surface of Al*. A passivation shell of Al* formed by these products is the kinetic barrier to the dehydrogenation of LiBH4/Al* composite.

scholarly journals Release of the Diclofenac Sodium by Nanofibers of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Obtained from Electrospinning and Solution Blow Spinning

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Michelle Andrade Souza ◽  
Karine Yamamura Sakamoto ◽  
Luiz Henrique Capparelli Mattoso
Keyword(s):  
Diclofenac Sodium ◽  
X Ray Diffraction ◽  
Fiber Morphology ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Polymer Nanofibers ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Solution Blow Spinning

Electrospun fibers are explored as a new system for controlled drug delivery. Novel techniques capable of obtaining polymer nanofibers have been reported in the literature. They include solution blow spinning (SBS), which is a technique to produce polymer nanofibers in the same range as electrospinning, using pressurized gas instead of high voltage. The present study investigates release characteristics of diclofenac sodium encapsulated at three concentrations (5, 10, and 20% w/v) in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers made by electrospinning and SBS and determines the drug’s effect on fiber morphology and structural properties. PHBV nanofibers were characterized using scanning electronic microscopy, differential scanning calorimetry, and X-ray diffraction, and the release profile was examined via UV-Vis spectrophotometry. Both electrospinning and SBS encapsulated diclofenac sodium in PHBV membranes efficiently and effectively. The profile of thein vitrorelease of diclofenac sodium was dependent on drug concentration and temperature. The drug reduced crystallinity and increased flexibility.

scholarly journals Hydrogen Desorption Properties of LiBH4/xLiAlH4 (x = 0.5, 1, 2) Composites

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1861 ◽  
Author(s):  
Qing He ◽  
Dongdong Zhu ◽  
Xiaocheng Wu ◽  
Duo Dong ◽  
Meng Xu ◽  
...  
Keyword(s):  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Mass Spectral ◽  
Effective Contact ◽  
Dehydrogenation Reactions ◽  
Kinetic Investigations ◽  
Determining Factor ◽  
Dehydrogenation Mechanism

A detailed analysis of the dehydrogenation mechanism of LiBH4/xLiAlH4 (x = 0.5, 1, 2) composites was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD) and scanning electronic microscopy (SEM), along with kinetic investigations using a Sievert-type apparatus. The results show that the dehydrogenation pathway of LiBH4/xLiAlH4 had a four-step character. The experimental dehydrogenation amount did not reach the theoretical expectations, because the products such as AlB2 and LiAl formed a passivation layer on the surface of Al and the dehydrogenation reactions associated with Al could not be sufficiently carried out. Kinetic investigations discovered a nonlinear relationship between the activation energy (Ea) of dehydrogenation reactions associated with Al and the ratio x, indicating that the Ea was determined both by the concentration of Al produced by the decomposition of LiAlH4 and the amount of free surface of it. Therefore, the amount of effective contact surface of Al is the rate-determining factor for the overall dehydrogenation of the LiBH4/xLiAlH4 composites.

Characterization of Shivirtui Zeolite Modified with Aluminum Oxyhydroxide Nanofibers

2019 ◽  
Vol 942 ◽  
pp. 40-49
Author(s):  
Yulia Murashkina ◽  
Olga B. Nazarenko
Keyword(s):  
Chemical Properties ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Aluminum Oxyhydroxide

Natural zeolite of Shivirtui deposit (Russia) was modified with nanofibers of aluminum oxyhydroxide AlOOH. Aluminum oxyhydroxide nanofibers were produced at the heating and oxidation of aluminum powder with water. The properties of modified zeolite were investigated by means of X-ray diffraction, transmission electronic microscopy, scanning electronic microscopy, low-temperature nitrogen adsorption, thermal analysis, and Fourier transform infrared spectroscopy. It was found that water content in the modified sample of zeolite was about 15 %. Based on the study of the physical and chemical properties, shivirtui zeolite modified with nanofibers of aluminum oxyhydroxide can be proposed for use as a flame-retardant additive to polymers.

Study of the Synthesis of Mullite From Kaolin-α-Al2O3 and Kaolin-Al(NO3)3

2012 ◽  
Vol 1481 ◽  
pp. 11-17
Author(s):  
E. M. Lozada ◽  
O. Alanís ◽  
F. Legorreta ◽  
L. E. Hernández
Keyword(s):  
Combustion Method ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Crystallographic Study ◽  
Incomplete Reaction ◽  
Α Al2o3

ABSTRACTThe synthesis of mullite from kaolin clay and two precursors of aluminum: α-Al2O3 and Al(NO3)3 was investigated. In order to study the temperature effect, the system kaolin-α-Al2O3 was calcined in air in a range of 1200 to 1500°C, for 2 h. For the system kaolin-Al(NO3)3, the combustion method was employed, using urea as fuel, and calcined in air at 1500°C for 2 h. The products were characterized by X-ray diffraction, scanning electronic microscopy (SEM), energy dispersive spectroscopy and particle size analysis in order to analyze and compare their morphology and structure. The crystallographic study revealed an incomplete reaction between the kaolin and the α-Al2O3. Nevertheless, in the system kaolin-Al(NO3)3, it was obtained mullite with high purity and trace amounts of cristobalite.

Fabrication and Magnetic Properties of Fe3O4 Nanobranches via a Simple Solvothermal Method

2011 ◽  
Vol 335-336 ◽  
pp. 934-939
Author(s):  
Z. F. Zi ◽  
Y. N. Liu ◽  
Q.C. Liu ◽  
Jian Ming Dai ◽  
Yu Ping Sun
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Solvothermal Method ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Water Solvent ◽  
Phase Spinel ◽  
Antisite Defects

Magnetite (Fe3O4) nanobranches were synthesized using an improved solvothermal technique in mixed ethanol and water solvent. Structural and magnetic properties were systematically investigated. X-ray diffraction results showed that the sample was single-phase spinel structure. The results of scanning electronic microscopy exhibited that the grains were regular like-branch with sizes from 3 to 6 μm in length and in diameter between 50 and 200 nm. The composition determined by energy dispersive spectroscopy was very close to the stoichiometry of Fe3O4. The saturation magnetizations (Ms) at 10 and 300 K of the synthesized Fe3O4nanobranches were much lower than the theoretical values. On one hand, it could be explained by obstructive magnetizing along their non-easy magnetic axes by the shape anisotropy of Fe3O4nanobranches, on the other hand, lesserMscan also be understood by the existence of antisite defects.

scholarly journals Structure and composition of soils

2010 ◽  
Vol 4 (4) ◽  
pp. 259-263 ◽  
Author(s):  
Snezana Nenadovic ◽  
Milos Nenadovic ◽  
Ljiljana Kljajevic ◽  
Vladimir Pavlovic ◽  
Aleksandar Djordjevic ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Porous Structure ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Characterization Methods ◽  
Soil Particles ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

This paper presents a study of soils structure and composition using up to date technique, such as scanning electronic microscopy, atomic force microscopy, X-ray diffraction, X-ray fluorescence, as well as some other characterization methods. It was shown that soil particles have porous structure and dimensions in the range from several millimeters to several hundreds of nanometers and consist of different minerals such as kaolin, quartz and feldspate.

Synthesis and Characteristics of Melamine Formaldehyde Composites

2014 ◽  
Vol 1040 ◽  
pp. 393-398 ◽  
Author(s):  
Yakha Visurkhanova ◽  
Nina Ivanova ◽  
Gulsum Tusupbekova ◽  
Daria Izbastenova
Keyword(s):  
Catalytic Activity ◽  
Transition Metals ◽  
X Ray Diffraction ◽  
Melamine Formaldehyde ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray

Melamine formaldehyde composites have been synthesized with chlorides and micro- and nanoparticles of transition metals (Co, Ni, Cu) entered into polymer during the polycondensation of melamine with formaldehyde. The received composites were studied by the X-ray diffraction and scanning electronic microscopy and applied as catalysts to cathode activation in cyclohexanone electrohydrogenation. For composites of MF+MCl2 it was established higher catalytic activity than for МF+М0.

Chemical Stability of Vb2 and ZrB2 with Aluminum

1990 ◽  
Vol 181 ◽  
Author(s):  
L. E. Halperin ◽  
E. Kolawa ◽  
Z. Fu ◽  
M-A. Nicolet
Keyword(s):  
Thin Films ◽  
Chemical Stability ◽  
Rf Sputtering ◽  
Heat Of Reaction ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystallization Reaction ◽  
Exothermic Chemical Reaction

ABSTRACTThe chemical stability of boride thin films with aluminum is investigated. Only two diborides, VB2 and HfB2 have a positive heat of reaction which makes them potential candidates for thermodynamically stable diffusion barriers between Al and Si. Thin films of VB2, and ZrB2 for comparison, prepared by rf sputtering of composite targets were chosen for this study. Multilayer samples of these borides and aluminum were investigated by differential scanning calorimetry to determine if, according to calculations, a reaction between Al and the borides takes place, and to measure the heat of reaction. We find that an exothermic chemical reaction occurs between ZrB2 and Al and that an exothermic crystallization reaction takes place in the VB2 and Al sample. The reaction products were determined using X-ray diffraction.

Effect of the Ratio of Zn/Y on Microstructure and Mechanical Properties of As-Cast Mg-4Zn-xY Alloys

2013 ◽  
Vol 395-396 ◽  
pp. 201-204
Author(s):  
Feng Wang ◽  
Ji Bao Li ◽  
Ping Li Mao ◽  
Zheng Liu
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Energy Dispersive Spectrum ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Uniformity Coefficient ◽  
Microstructure And Mechanical Properties ◽  
Second Phases

In order to investigate the ratio of Zn/Y on as-cast Mg-4Zn-xY (x=1, 2, 3 in wt. %), microstructure and mechanical properties are analyzed by scanning electronic microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrum (EDS) and tensile testing. The results indicate that with the decrease of the ratio of Zn/Y, microstructures are refined more greatly and the spheroidization and uniformity coefficient are improved obviously, and the morphologies of second phases are changed from diversity to unity, resulting in an improvement of mechanical properties of alloys.

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