New Porous Materials from Layered Compounds

Clearfield, Abraham; Kuchenmeister, M. E.; Wang, Jiandang; Wade, K.L.

doi:10.1016/s0167-2991(08)61604-3

Cited by 7 publications

(1 citation statement)

References 38 publications

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“…Anions can be simple ones, as carbonate, nitrate, chloride, etc., or bulk anions, such as polyoxometalates or even Keggin, Finke, or Dawson-type anions. The height of the interlayer space depends both on the nature of the anion and on its orientation, if it is not spherical. − Intercalation of these anions can be achieved following different methods, and in some cases, preswelling of the layers is required. , …”

Section: Introductionmentioning

confidence: 99%

Intercalation of [Cr(C₂O₄)₃]³^-Complex in Mg,Al Layered Double Hydroxides

et al. 2003

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A Mg,Al layered double hydroxide (LDH) with [Cr(C(2)O(4))(3)](3)(-) anions in the interlayer has been synthesized following two different routes: reconstruction from a mildly calcined Mg,Al-carbonate LDH, and anion exchange from a Mg,Al-nitrate LDH. The solids prepared have been characterized by elemental chemical analysis, powder X-ray diffraction, FT-IR and UV-vis/DR (diffuse reflectance) spectroscopies, thermal methods, nitrogen adsorption at -196 degrees C, and FT-IR monitoring of pyridine adsorption. The results obtained indicate that the most appropriate method is anion exchange, leading to a well crystallized LDH with an interlayer spacing of 10 A. Due to the high pH value (>8) of the solution in the reconstruction method, however, a polyphasic system is obtained, where, in addition to a phase with the LDH structure, amorphous magnesium oxalate and chromium oxohydroxides are also formed due to hydrolysis of the complex. The interlayer complex is stable up to 200 degrees C, but the layered structure is stable up to 330 degrees C, probably because of the presence of interlayer oxalate anions formed during decomposition of the complex. Calcination leads to oxidation of Cr(3+) ions to the six-valent state, which reverts to Cr(3+) when the calcination temperature is further increased.

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