• Title/Summary/Keyword: Hydrogen behavior

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Particle Size and Reaction Temperature Effects on the Hydrolysis Reaction of Zinc in TGA (Thermo Gravimetric Analyzer) (열 중량 분석기에서 zinc 입자 크기와 반응 온도에 따른 물 분해 특성 연구)

  • Ahn, Seung-Hyuck;Kang, Kyoung-Soo;Kim, Chang-Hee;Bae, Ki-Kwang;Kim, Young-Ho;Park, Chu-Sik
    • Journal of Hydrogen and New Energy
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    • v.19 no.4
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    • pp.305-312
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    • 2008

  • ZnO/Zn redox cycle is the one of the promising thermochemical cycles for hydrogen production via water splitting with high temperature heat source like a concentrated solar energy. This paper reports the particle size effect of Zinc on water splitting behavior. Water splitting reaction experiments were carried out at isothermal conditions of 350 and 400$^{\circ}C$ in TGA (Thermo Gravimetric Analyzer) using four commercial Zinc powders (nano, <10 ${\mu}m$, <150 ${\mu}m$ and $150{\sim}600\;{\mu}m$ particle sizes). Before the experiments, average particle size of Zinc powders was analyzed by PSA (Particle Size Analysis). After the experiments, XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscope) analyses were conducted on the samples. The experimental results showed that particle size had a effect on the conversion of Zinc to ZnO. Zinc conversion was increased, as the particle size decreased. Especially, the nano size particles were aggregated and the particle's morphology changed on the surface during hydrolysis reaction.

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The Effect of Planetary Ball Mill Process on the Hydrogenation Behavior of Mg2NiHx (Mg2NiHx 수소화거동에 미치는 기계적합금화 공정의 영향)

  • Lim, Jae-Won;Ha, Won;Hong, Tae-Whan;Kim, Shae-Kwang;Kim, Young-Jig;Park, Hyun-Soon
    • Journal of Hydrogen and New Energy
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    • v.10 no.2
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    • pp.131-139
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    • 1999

  • The objective of this works was to synthesize the$Mg_2Ni$ hydrogen storage materials economically and to eliminate the intial activation process. $Mg_2NiH_x$ was mechanically alloyed under purified hydrogen gas atmosphere using pure Mg and Ni chips. M.A(Mechanical Alloying) was carried out using planetary ball mill for times varying from 12h to 96h under 20bars of hydrogen gas pressure. $Mg_2NiH_x$ started to form after 48h and the homogeneous $Mg_2NiH_x$ composites was synthesized after 96h. From TG analysis, the dehydriding reaction of $Mg_2NiH_x$ started at around $200^{\circ}C$. The result of P-C-T at $300^{\circ}C$ revealed the hydrogen storage capacity of $Mg_2NiH_c$ reached 3.68 wt% and the effective hydrogen storage was 2.38 wt%. The enthalpy difference of absorption-desorption cycling for the hydride formation and the hysteresis were reduced and the plateau flatness and the sloping were improved according to M.A time.

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