The Experts below are selected from a list of 657 Experts worldwide ranked by ideXlab platform

Yoshitsugu Kojima - One of the best experts on this subject based on the ideXlab platform.

  • improved hydrogen desorption from lithium hydrazide by Alkali Metal Hydride
    Journal of Alloys and Compounds, 2013
    Co-Authors: Liang Zeng, Hiroki Miyaoka, Takayuki Ichikawa, Yoshitsugu Kojima
    Abstract:

    Abstract Lithium hydrazide (LiNHNH 2 ), which is a white solid with 8.0 mass% of theoretical hydrogen content, was synthesized from a reaction between anhydrous hydrazine and n -butyllithium in diethyl ether. The thermodynamic properties of this compound and its detailed decomposition pathways had been investigated in our previous work. However, a number of undesired gaseous products such as hydrazine (N 2 H 4 ) and ammonia (NH 3 ) were generated during the thermal decomposition of LiNHNH 2 . In this work, Alkali Metal Hydride was used to suppress the impurities in the desorbed hydrogen and improved the hydrogen desorption properties. The reaction mechanism between LiNHNH 2 and LiH was also studied and discussed in this paper.

  • compressed hydrogen production via reaction between liquid ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Hiroki Miyaoka, Takayuki Ichikawa, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia NH3 is recognized as one of the attractive hydrogen H2 carriers because it has a high hydrogen content of 18 mass% and it is easily liquefied under about 1 MPa of pressure at a room temperature. NH3 can react with Alkali Metal Hydrides and generate H2 even at room temperature, resulting that Metal amides are formed as reaction products. The H2 generation is exothermic reaction, and it is not effectively prevented by H2 partial pressure in a closed system as thermodynamic properties. In this work, we demonstrated the production of compressed H2 by the reaction between liquid NH3 and lithium Hydride LiH in a closed pressure vessel, where liquid NH3 would realize better kinetic properties for the reaction with Metal Hydride than gaseous NH3. Actually, more than 12 MPa H2 was obtained within several hours.

  • recyclable hydrogen storage system composed of ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Hikaru Yamamoto, Hiroki Miyaoka, Takayuki Ichikawa, Haruyuki Nakanishi, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia (NH3) reacts with Alkali Metal Hydrides MH (M = Li, Na, and K) in an exothermic reaction to release hydrogen (H2) at room temperature, resulting that Alkali Metal amides (MNH2) which are formed as by-products. In this work, hydrogen desorption properties of these systems and the condition for the recycle from MNH2 back to MH were investigated systematically. For the hydrogen desorption reaction, the reactivities of MH with NH3 were better following the atomic number of M on the periodic table, Li

Ping Chen - One of the best experts on this subject based on the ideXlab platform.

  • Alkali Metal Hydride modification on hydrazine borane for improved dehydrogenation
    Journal of Physical Chemistry C, 2014
    Co-Authors: Yong Shen Chua, Zhitao Xiong, Qijun Pei, Wei Zhou, Terrence J Udovic, Ping Chen
    Abstract:

    Hydrazidotrihydridoborates of various Alkali Metals, i.e., NaN2H3BH3 and KN2H3BH3, were synthesized successfully via a liquid approach. The crystal structures of NaN2H3BH3 and KN2H3BH3 were determined, and their dehydrogenation properties were compared with LiN2H3BH3 and N2H4BH3. A clear correlation between sizes of Metal cations in hydrazidotrihydridoborates and their corresponding melting and dehydrogenation temperatures was observed. The dehydrogenation temperature was found dependent on the melting temperature. Upon approaching the melting points, Alkali Metal hydrazidotrihydridoborates dehydrogenate rapidly in the first step, giving rise to the formation of intermediates that possess N2BH2, N2BH, and NBH3 species. Further increasing temperature leads to the release of additional H2 and the formation of N2BH species. Compared to pristine N2H4BH3, the Alkali-Metal-substituted hydrazidotrihydridoborates demonstrate significantly improved dehydrogenation behavior with no N2H4 emission and greatly suppres...

  • Hydrogen storage over Alkali Metal Hydride and Alkali Metal hydroxide composites
    Journal of Energy Chemistry, 2014
    Co-Authors: Yong Shen Chua, Hujun Cao, Zhitao Xiong, Ping Chen
    Abstract:

    Alkali Metal hydroxide and Hydride composite systems contain both protic (H bonded with O) and hydridic hydrogen. The interaction of these two types of Hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of Alkali Metals, i.e., −23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150 °C; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2, and the corresponding entropy was ca. 101.23 J/(molH2·K), so the temperature for releasing 1.0 bar H2 was as high as 518 °C, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be 57.87 kJ/mol, showing good kinetic properties.

Yong Shen Chua - One of the best experts on this subject based on the ideXlab platform.

  • Alkali Metal Hydride modification on hydrazine borane for improved dehydrogenation
    Journal of Physical Chemistry C, 2014
    Co-Authors: Yong Shen Chua, Zhitao Xiong, Qijun Pei, Wei Zhou, Terrence J Udovic, Ping Chen
    Abstract:

    Hydrazidotrihydridoborates of various Alkali Metals, i.e., NaN2H3BH3 and KN2H3BH3, were synthesized successfully via a liquid approach. The crystal structures of NaN2H3BH3 and KN2H3BH3 were determined, and their dehydrogenation properties were compared with LiN2H3BH3 and N2H4BH3. A clear correlation between sizes of Metal cations in hydrazidotrihydridoborates and their corresponding melting and dehydrogenation temperatures was observed. The dehydrogenation temperature was found dependent on the melting temperature. Upon approaching the melting points, Alkali Metal hydrazidotrihydridoborates dehydrogenate rapidly in the first step, giving rise to the formation of intermediates that possess N2BH2, N2BH, and NBH3 species. Further increasing temperature leads to the release of additional H2 and the formation of N2BH species. Compared to pristine N2H4BH3, the Alkali-Metal-substituted hydrazidotrihydridoborates demonstrate significantly improved dehydrogenation behavior with no N2H4 emission and greatly suppres...

  • Hydrogen storage over Alkali Metal Hydride and Alkali Metal hydroxide composites
    Journal of Energy Chemistry, 2014
    Co-Authors: Yong Shen Chua, Hujun Cao, Zhitao Xiong, Ping Chen
    Abstract:

    Alkali Metal hydroxide and Hydride composite systems contain both protic (H bonded with O) and hydridic hydrogen. The interaction of these two types of Hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of Alkali Metals, i.e., −23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150 °C; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2, and the corresponding entropy was ca. 101.23 J/(molH2·K), so the temperature for releasing 1.0 bar H2 was as high as 518 °C, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be 57.87 kJ/mol, showing good kinetic properties.

Hiroki Miyaoka - One of the best experts on this subject based on the ideXlab platform.

  • improved hydrogen desorption from lithium hydrazide by Alkali Metal Hydride
    Journal of Alloys and Compounds, 2013
    Co-Authors: Liang Zeng, Hiroki Miyaoka, Takayuki Ichikawa, Yoshitsugu Kojima
    Abstract:

    Abstract Lithium hydrazide (LiNHNH 2 ), which is a white solid with 8.0 mass% of theoretical hydrogen content, was synthesized from a reaction between anhydrous hydrazine and n -butyllithium in diethyl ether. The thermodynamic properties of this compound and its detailed decomposition pathways had been investigated in our previous work. However, a number of undesired gaseous products such as hydrazine (N 2 H 4 ) and ammonia (NH 3 ) were generated during the thermal decomposition of LiNHNH 2 . In this work, Alkali Metal Hydride was used to suppress the impurities in the desorbed hydrogen and improved the hydrogen desorption properties. The reaction mechanism between LiNHNH 2 and LiH was also studied and discussed in this paper.

  • compressed hydrogen production via reaction between liquid ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Hiroki Miyaoka, Takayuki Ichikawa, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia NH3 is recognized as one of the attractive hydrogen H2 carriers because it has a high hydrogen content of 18 mass% and it is easily liquefied under about 1 MPa of pressure at a room temperature. NH3 can react with Alkali Metal Hydrides and generate H2 even at room temperature, resulting that Metal amides are formed as reaction products. The H2 generation is exothermic reaction, and it is not effectively prevented by H2 partial pressure in a closed system as thermodynamic properties. In this work, we demonstrated the production of compressed H2 by the reaction between liquid NH3 and lithium Hydride LiH in a closed pressure vessel, where liquid NH3 would realize better kinetic properties for the reaction with Metal Hydride than gaseous NH3. Actually, more than 12 MPa H2 was obtained within several hours.

  • recyclable hydrogen storage system composed of ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Hikaru Yamamoto, Hiroki Miyaoka, Takayuki Ichikawa, Haruyuki Nakanishi, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia (NH3) reacts with Alkali Metal Hydrides MH (M = Li, Na, and K) in an exothermic reaction to release hydrogen (H2) at room temperature, resulting that Alkali Metal amides (MNH2) which are formed as by-products. In this work, hydrogen desorption properties of these systems and the condition for the recycle from MNH2 back to MH were investigated systematically. For the hydrogen desorption reaction, the reactivities of MH with NH3 were better following the atomic number of M on the periodic table, Li

Takayuki Ichikawa - One of the best experts on this subject based on the ideXlab platform.

  • improved hydrogen desorption from lithium hydrazide by Alkali Metal Hydride
    Journal of Alloys and Compounds, 2013
    Co-Authors: Liang Zeng, Hiroki Miyaoka, Takayuki Ichikawa, Yoshitsugu Kojima
    Abstract:

    Abstract Lithium hydrazide (LiNHNH 2 ), which is a white solid with 8.0 mass% of theoretical hydrogen content, was synthesized from a reaction between anhydrous hydrazine and n -butyllithium in diethyl ether. The thermodynamic properties of this compound and its detailed decomposition pathways had been investigated in our previous work. However, a number of undesired gaseous products such as hydrazine (N 2 H 4 ) and ammonia (NH 3 ) were generated during the thermal decomposition of LiNHNH 2 . In this work, Alkali Metal Hydride was used to suppress the impurities in the desorbed hydrogen and improved the hydrogen desorption properties. The reaction mechanism between LiNHNH 2 and LiH was also studied and discussed in this paper.

  • compressed hydrogen production via reaction between liquid ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Hiroki Miyaoka, Takayuki Ichikawa, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia NH3 is recognized as one of the attractive hydrogen H2 carriers because it has a high hydrogen content of 18 mass% and it is easily liquefied under about 1 MPa of pressure at a room temperature. NH3 can react with Alkali Metal Hydrides and generate H2 even at room temperature, resulting that Metal amides are formed as reaction products. The H2 generation is exothermic reaction, and it is not effectively prevented by H2 partial pressure in a closed system as thermodynamic properties. In this work, we demonstrated the production of compressed H2 by the reaction between liquid NH3 and lithium Hydride LiH in a closed pressure vessel, where liquid NH3 would realize better kinetic properties for the reaction with Metal Hydride than gaseous NH3. Actually, more than 12 MPa H2 was obtained within several hours.

  • recyclable hydrogen storage system composed of ammonia and Alkali Metal Hydride
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Hikaru Yamamoto, Hiroki Miyaoka, Takayuki Ichikawa, Haruyuki Nakanishi, Satoshi Hino, Yoshitsugu Kojima
    Abstract:

    Abstract Ammonia (NH3) reacts with Alkali Metal Hydrides MH (M = Li, Na, and K) in an exothermic reaction to release hydrogen (H2) at room temperature, resulting that Alkali Metal amides (MNH2) which are formed as by-products. In this work, hydrogen desorption properties of these systems and the condition for the recycle from MNH2 back to MH were investigated systematically. For the hydrogen desorption reaction, the reactivities of MH with NH3 were better following the atomic number of M on the periodic table, Li