An in-situ X-ray Diffraction Study of the Desorption of TiCl3-doped Sodium Alanate

MRS Proceedings ◽

10.1557/proc-837-n3.3 ◽

2004 ◽

Vol 837 ◽

Author(s):

Scott A. Speakman ◽

Joachim H. Schneibel ◽

Dewey S. Easton

Keyword(s):

Rate Constants ◽

Hydrogen Desorption ◽

Hydrogen Release ◽

Desorption Rate ◽

X Ray Diffraction ◽

X Ray ◽

Sodium Alanate ◽

Temperature Programmed ◽

Type Apparatus

ABSTRACTSodium alanate was milled with and without TiCl3. The hydrogen release and uptake was measured during temperature-programmed absorption and desorption, as well as by isothermal charging and discharging, using a Sieverts' type apparatus. These data were supplemented by in-situ X-ray diffraction studies of hydrogen desorption. Rate constants derived from XRD were slower than those derived from volumetric H2 measurements. Al formation observed in XRD exceeded that expected from the observed decomposition of NaAlH4 and Na3AlH6.

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Development of a Novel Method for the Fabrication of Nanostructured Zr(x)Ni(y) Catalyst to Enhance the Desorption Properties of MgH2

Catalysts ◽

10.3390/catal10080849 ◽

2020 ◽

Vol 10 (8) ◽

pp. 849

Author(s):

Gracia Shokano ◽

Zahir Dehouche ◽

Basile Galey ◽

Georgeta Postole

Keyword(s):

Hydrogen Desorption ◽

Milling Process ◽

Hydrogen Release ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Electron Microscope Analysis ◽

Novel Method ◽

Temperature Programmed ◽

The Impact

The present work involves the development of a novel method for the fabrication of zirconium nickel (Zr(x)Ni(y)) alloy used as a nanocatalyst to improve the hydrogen storage properties of the Mg/MgH2 system. The catalyst was fabricated through the high-pressure reactor and activated under hydrogen prior to being mechanically milled with the MgH2 for 5 h under argon. The microstructure characterisation of the samples was determined via SEM-EDX (scanning electron microscope analysis–energy dispersive X-ray spectroscopy), XRD (X-ray diffraction) and FE-HRTEM (field emission high resolution transmission electron microscopy), and the desorption characteristic of the nanocomposite (10 wt.% Zr(x)Ni(y)–MgH2) was determined via TPD (temperature-programmed desorption). The nanostructured MgH2 powder milled with 10 wt.% of the activated Zr(x)Ni(y) based nanocatalyst resulted in a faster hydrogen release—5.9 H2-wt.% at onset temperature 210 °C/peak temperature 232 °C. The observed significant improvement in the hydrogen desorption properties was likely to be the result of the impact of the highly dispersed catalyst on the surface of the Mg/MgH2 system, the reduction in particle size during the ball milling process and/or the formation of Mg0.996Zr0.004 phase during the milling process.

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The Effects of Oxidized and Oxide-Free Boron on the Mg-B-H Nanohydrides Transformation in the Nearly Nanosized Powders

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.128.47 ◽

2007 ◽

Vol 128 ◽

pp. 47-52 ◽

Cited By ~ 3

Author(s):

R.A. Varin ◽

Ch. Chiu ◽

Zbigniew S. Wronski ◽

Andrzej Calka

Keyword(s):

Hydrogen Desorption ◽

Hydrogen Release ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Nanosized Powders ◽

X Ray ◽

Milled Sample ◽

Heat Event ◽

Reactive Mechanical Alloying ◽

Type Apparatus

In this work oxidized and oxide-free amorphous boron (a-B) powder and elemental Mg were used in an attempt to directly synthesize the Mg(BH4)2 complex hydride by controlled reactive mechanical alloying (CRMA) under hydrogen in a magneto-mill up to 200h. The particle size was refined to the 100-200nm range. Nanocrystalline MgH2 (~6nm crystallite size) was formed within the particles when an oxidized a-B is used. In contrast, a mixture of MgB2 and an amorphous hydride MgHx was formed when an oxide-free a-B was used. Differential scanning calorimetry (DSC) test up to 500°C produced a single endothermic heat event at 357.7°C due to hydrogen desorption. In addition, desorption conducted in a Sieverts-type apparatus revealed ~1.4wt.% of hydrogen release. The X-ray diffraction pattern after DSC test of the 200h milled sample made with oxide-free boron showed the presence of MgB2.

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Effect of Heat Treatments on TiH2: Surface Composition and Hydrogen Release

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.2032 ◽

2016 ◽

Vol 879 ◽

pp. 2032-2037 ◽

Cited By ~ 2

Author(s):

Gabriele Lapi ◽

Carlo Alvani ◽

Francesca Varsano ◽

Saulius Kaciulis ◽

Roberto Montanari ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Titanium Hydride ◽

Surface Composition ◽

Hydrogen Desorption ◽

Temperature Programmed Desorption ◽

Heat Treatments ◽

Hydrogen Release ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Programmed

The present work investigates the effect of heat treatments in air on the surface and structure of titanium hydride (TiH2) and hydrogen desorption. TiH2 has been heated in air at 440 and 540 °C for increasing time up to 180 min. to obtain the samples representative of 12 different oxidation conditions. The samples have been then examined by Temperature Programmed Desorption (TPD), X-Ray Diffraction (XRD) and Photoelectron Spectroscopy (XPS). Experimental results are presented and discussed.

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Hydrogen desorption properties of melt-spun and hydrogenated Mg-based alloys using in situ synchrotron X-ray diffraction and TGA

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2010.10.067 ◽

2011 ◽

Vol 509 ◽

pp. S629-S632 ◽

Cited By ~ 7

Author(s):

Siarhei Kalinichenka ◽

Lars Röntzsch ◽

Carsten Baehtz ◽

Thomas Weißgärber ◽

Bernd Kieback

Keyword(s):

Hydrogen Desorption ◽

X Ray Diffraction ◽

X Ray ◽

Melt Spun

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Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Catalysts ◽

10.3390/catal9090768 ◽

2019 ◽

Vol 9 (9) ◽

pp. 768 ◽

Cited By ~ 2

Author(s):

Shuang Ding ◽

Jiankang Zhao ◽

Qiang Yu

Keyword(s):

Propionic Acid ◽

Vapor Phase ◽

Surface Concentration ◽

X Ray Diffraction ◽

In Situ Drifts ◽

X Ray ◽

Surface Intermediates ◽

Temperature Programmed ◽

Diffuse Reflectance Infrared

Vapor-phase ketonization of propionic acid derived from biomass was studied at 300–375 °C over ZrO2 with different zirconia polymorph. The tetragonal ZrO2 (t-ZrO2) are more active than monoclinic ZrO2 (m-ZrO2). The results of characterizations from X-ray diffraction (XRD) and Raman suggest m-ZrO2 and t-ZrO2 are synthesized by the solvothermal method. NH3 and CO2 temperature-programmed desorption (NH3-TPD and CO2-TPD) measurements show that there were more medium-strength Lewis acid base sites with lower coordination exposed on m-ZrO2 relative to t-ZrO2, increasing the adsorption strength of propionic acid. The in situ DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy) of adsorbed propionic acid under ketonization reaction reveal that as the most abundant surface intermediates, the monodentate propionates are more active than bidentate propionates. In comparison with m-ZrO2, the t-ZrO2 surface favors monodentate adsorption over bidentate adsorption. Additionally, the adsorption strength of monodentate propionate is weaker on t-ZrO2. These differences in adsorption configuration and adsorption strength of propionic acid are affected by the zirconia structure. The higher surface concentration and weaker adsorption strength of monodentate propionates contribute to the higher ketonization rate in the steady state.

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“PdO vs. PtO”—The Influence of PGM Oxide Promotion of Co3O4 Spinel on Direct NO Decomposition Activity

Catalysts ◽

10.3390/catal9010062 ◽

2019 ◽

Vol 9 (1) ◽

pp. 62 ◽

Cited By ~ 3

Author(s):

Gunugunuri K. Reddy ◽

Torin C. Peck ◽

Charles A. Roberts

Keyword(s):

Photoelectron Spectroscopy ◽

No Decomposition ◽

Single Element ◽

X Ray Diffraction ◽

X Ray ◽

Promotional Effect ◽

Ft Ir ◽

Temperature Programmed ◽

Thermal Stability Of

Direct decomposition of NO into N2 and O2 (2NO→N2 + O2) is recognized as the “ideal” reaction for NOx removal because it needs no reductant. It was reported that the spinel Co3O4 is one of the most active single-element oxide catalysts for NO decomposition at higher reaction temperatures, however, activity remains low below 650 °C. The present study aims to investigate new promoters for Co3O4, specifically PdO vs. PtO. Interestingly, the PdO promoter effect on Co3O4 was much greater than the PtO effect, yielding a 4 times higher activity for direct NO decomposition at 650 °C. Also, Co3O4 catalysts with the PdO promoter exhibit higher selectivity to N2 compared to PtO/Co3O4 catalysts. Several characterization measurements, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and in situ FT-IR, were performed to understand the effect of PdO vs. PtO on the properties of Co3O4. Structural and surface analysis measurements show that impregnation of PdO on Co3O4 leads to a greater ease of reduction of the catalysts and an increased thermal stability of surface adsorbed NOx species, which contribute to promotion of direct NO decomposition activity. In contrast, rather than remaining solely as a surface species, PtO enters the Co3O4 structure, and it promotes neither redox properties nor NO adsorption properties of Co3O4, resulting in a diminished promotional effect compared to PdO.

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In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

Catalysts ◽

10.3390/catal10070807 ◽

2020 ◽

Vol 10 (7) ◽

pp. 807

Author(s):

Zen Maeno ◽

Xiaopeng Wu ◽

Shunsaku Yasumura ◽

Takashi Toyao ◽

Yasuharu Kanda ◽

...

Keyword(s):

Active Sites ◽

Temperature Programmed Desorption ◽

X Ray Diffraction ◽

Zeolite Framework ◽

X Ray ◽

Catalytic Activities ◽

Ethane Dehydrogenation ◽

Temperature Programmed

In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites.

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Sodium Alanate Dehydrogenation Properties Enhanced by MnTiO3 Nanoparticles

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2020.2706 ◽

2020 ◽

Vol 15 (2) ◽

pp. 197-203

Author(s):

Yujie Sun ◽

Xia Yang ◽

Yue Huang ◽

Jianquan Li ◽

Xinghua Cen ◽

...

Keyword(s):

Solid State ◽

Hydrogen Desorption ◽

Test Results ◽

X Ray Diffraction ◽

X Ray ◽

Sodium Alanate ◽

State Ceramic ◽

Solid State Ceramic Route ◽

Ceramic Route ◽

First Time

In this study, we investigated the influence of MnTiO3 nanoparticles additive on hydrogen released performance of NaAlH4 for the first time. The MnTiO3 nanoparticles were successfully synthesized using conventional solid-state ceramic route. It was found that the hydrogen released performance of NaAlH4 can be significantly improved by the addition of MnTiO3 nanoparticles. Meantime, the composite of NaAlH4 doped 5 wt% MnTiO3 possessed excellent dehydrogenation properties, the onset dehydrogenation temperature was only 70.6 °C, reduced by about 105 °C in comparison with the pristine NaAlH4, and approximately 5.01 wt% of hydrogen could be released from composite with temperature heated to 220 °C. The isothermal dehydrogenation test results indicated that the amount of hydrogen released by NaAlH4-5 wt% MnTiO3 composite could reach 4.4 wt% under 200 °C within 25 min. According to the analysis of X-ray diffraction, the presence of MnTiO3 nanoparticles did not alter the overall dehydrogenation pathway of NaAlH4, and the Al3 Ti phases formed after dehydrogenation, which enhanced hydrogen desorption performances of NaAlH4 .

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