Kinetics study of sodium alanate with catalyst TiO 2

Khan, Junaid; Jain, I.P.

doi:10.1016/j.rser.2015.07.136

“…Different types of catalysts such as metal, 10,17 metal oxide, 11,18 and metal halide 19,20 have been doped into NaAlH 4 . Recently, Khan and Jain 21 reported that TiO 2 -doped NaAlH 4 showed faster desorption kinetics with improved hydrogen capacity (3.6–5.1 wt %) at 250 °C, while the study on the effect of Nb 2 O 5 on the dehydrogenation kinetics of NaAlH 4 revealed that the amount of desorbed hydrogen varied between 4.8 and 5.0 wt % at 250 °C following the catalyst content. 22 In the other study on the effect of metal chlorides (TiCl 3 , PdCl 2 , and CeCl 3 ) on the hydrogen desorption of NaAlH 4 , Khan and Jain 23 found that the amount of hydrogen desorbed at a temperature below 150 °C was less than 1 wt %.…”

Section: Introductionmentioning

confidence: 99%

“…Different types of catalysts such as metal, 10,17 metal oxide, 11,18 and metal halide 19,20 have been doped into NaAlH 4 . Recently, Khan and Jain 21 reported that TiO 2 -doped NaAlH 4 showed faster desorption kinetics with improved hydrogen capacity (3.6−5.1 wt %) at 250 °C, while the study on the effect of Nb 2 O 5 on the dehydrogenation kinetics of NaAlH 4 revealed that the amount of desorbed hydrogen varied between 4. 5.0 wt % at 250 °C following the catalyst content.…”

Section: ■ Introductionmentioning

confidence: 99%

Dehydrogenation Properties and Catalytic Mechanism of the K₂NiF₆-Doped NaAlH₄ System

Mustafa

¹

,

Yahya

²

,

Sazelee

³

et al. 2018

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The K 2 NiF 6 catalytic effect on the NaAlH 4 dehydrogenation properties was studied in this work. The desorption temperature was studied using temperature-programmed desorption and exhibited a lower onset hydrogen release after doped with different wt % of K 2 NiF 6 (5, 10, 15 and 20 wt %). It was found that the NaAlH 4 doped with 5 wt % K 2 NiF 6 showed the optimal value that can reduce the onset desorption temperature of about 160 °C compared to 190 °C for the milled NaAlH 4 . The NaAlH 4 + 5 wt % K 2 NiF 6 sample showed faster desorption kinetics where 1.5 wt % of hydrogen was released in 30 min at 150 °C. In contrast, the milled NaAlH 4 only released about 0.2 wt % within the same time and temperature. From the Kissinger analysis, the apparent activation energy was 114.7 kJ/mol for the milled NaAlH 4 and 89.9 kJ/mol for the NaAlH 4 -doped 5 wt % K 2 NiF 6 , indicating that the addition of K 2 NiF 6 reduced the activation energy for hydrogen desorption of NaAlH 4 . It is deduced that the new phases of AlNi, NaF, and KH that were formed in situ during the dehydrogenation process are the key factors for the improvement of dehydrogenation properties of NaAlH 4 .

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“…For 4% TiO 2 eNaAlH 4 , approximately 5.1 wt% H 2 is released under low temperatures (200 C to 250 C). Notably, the hydrogen storage capacity increases as the amount of catalyst increases [197]. TiO 2 is found to be a better catalyst than the previously reported ones for the desorption of hydrogen by NaAlH 4 [85,172] …”

Section: Transition Metal Oxidesmentioning

confidence: 86%

“…TiO 2 was determined to be the most effective catalyst [197,198]. The TiO 2 catalyst achieved great performance in NaAlH 4 with improved kinetics at low temperatures.…”

Section: Transition Metal Oxidesmentioning

confidence: 99%