Synthesis and Characterization of Zn-Al Layered Double Hydroxide and Its Applications in Hydrogen Adsorption
Date Issued
2011
Date
2011
Author(s)
Hsu, Che-Lun
Abstract
Zn-Al layered double hydroxides (LDHs) materials intercalated with different anions were synthesized by co-precipitation method under pH values around 9. Given that the thickness of a brucite-like layer is 4.8 Å, the gallery height is varied by intercalating different anions in between the layers. The relationship between the different intercalated anions and the hydrogen adsorption capabilities of the resultant materials were examined. All the LDHs materials were characterized with XRD to confirm the layered structure and ICP-MS to confirm the Zn/Al ratio . The chemical formulae were determined by the weight losses in TGA. The particle morphologies and sizes of the Zn-Al LDHs were examined by SEM. The specific surface areas and pore volumes were determined from the nitrogen adsorption isotherm at 1 atm and 77K. Finally, the hydrogen uptakes of the LDHs were measured at 1atm and 77K using the volumetric method. The hydrogen uptakes of the LDHs containing different anions decrese in the order of 1,4-biphenyldicarboxylate (BPDCA) > p-toluate (PTA) > terephthalate (TA) . Among them, Zn-Al LDH intercalated with a 1:1 ratio of mixed 1,4-biphenyldicarboxylate (BPDCA) and acetate (AA) gave the highest hydrogen uptake of 0.268 wt%. The LDHs containing borate have surface area larger than 200 m2/g, and the hydrogen uptakes are more than LDHs containing carboxylate anion.
Subjects
Layered double hydroxides
hydrogen storage
carboxylate
borate
Type
thesis
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