Structural studies of pillared clays and modified pillared clays
The long-range order of pillared interlayered clays (PILCs) after acid activation with 0.05N HCl has been investigated by X-ray diffraction (XRD) methods. The data show that long-range order in PILCs decreases as AlCH-PB = ZrCH-PB much greater than Zr/AlCH-PB = Cr/AlCH-PB (PB = pillared bentonite; MCH = metal chlorohydroxy pillaring agent, where M = Al, Zr or Cr). Apparently, pure oxide clusters are more stable than mixed oxide clusters. Treatment of PILCs with dilute HCl at 25/sup 0/C is less damaging than at reflux temperature, and calcined PILCs are more stable than air-dried materials. More structural damage occurs with 3M sulfuric acid treatment than with dilute HCl. Treatment with a weak base also causes some degradation of the pillars. /sup 27/Al-MAS NMR has been used to study pillared hectorite (PH), as well as other clay systems. The large increase of the observable octahedral aluminum (Al(VI)) resonance seen after pillaring is explained by loss of water from the (Al/sub 13/O/sub 4/(OH)/sub 24/(H/sub 2/O)/sub 12/)/sup 7 +/ (Al/sub 13/) cation. /sup 27/Al spectra of PILCs derived from different pillaring agents and exposed to various heat and acid treatments are remarkably similar. 16 refs., 1 fig., 1 tab.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5573449
- Report Number(s):
- CONF-871124-75; ON: DE88005954
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602* -- Other Materials-- Structure & Phase Studies
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Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACIDIFICATION
ALUMINIUM 27
ALUMINIUM ISOTOPES
BENTONITE
CALCINATION
CHEMICAL REACTIONS
CLAYS
COHERENT SCATTERING
DECOMPOSITION
DIFFRACTION
HEAT TREATMENTS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
PYROLYSIS
RESONANCE
SCATTERING
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
THERMOCHEMICAL PROCESSES
X-RAY DIFFRACTION