J. Jamis et al., FTIR SPECTROSCOPIC STUDY OF THE ADSORPTION OF HYDROGEN-CYANIDE BY METALLO-OXIDE PILLARED CLAYS, Chemistry of materials, 7(11), 1995, pp. 2078-2085
The IR spectra due to hydrogen cyanide adsorbed by montmorillonite, mo
ntmorillonite pillared by the oxides of aluminum, zirconium, iron, tit
anium and chromium, montmorillonite pillared by mixed oxides of alumin
um/zirconium, chromium/zirconium, iron/zirconium, and chromium/iron/zi
rconium, acid washed montmorillonite, and acid-washed montmorillonite
pillared by oxides of aluminum and zirconium have been recorded at var
ious temperatures of thermal pretreatment of the pillared clays. Simil
ar measurements have been made on hectorite and hectorite pillared by
the oxides of aluminum and zirconium. Substantial binding of hydrogen
cyanide by Lewis acid sites on the oxide pillars of the clays has been
shown to take place after heating the pillared clays to 673 K. The fo
rmation of such centres on the oxide pillared montmorillonite falls in
the order Al > Ti > Zr >> Fe, being undetectable for chromium. The ef
fect of the oxide pillar on the sheet structure of the clay is the pro
duction of binding sites on montmorillonite or hectorite similar to th
ose observed in zeolite Y and, additionally, a distinctive site charac
terized by an IR spectral band in the 2140 cm(-1) region which is thou
ght to be formed by disruption of the sheet structure with participati
on of the pillar material. The extent of formation of this site on the
sheet structure of montmorillonite increases in the order of the oxid
es of Al < Fe < Zr < Ti < Cr and again for hectorite its formation is
small for pillaring by aluminum oxide and extensive for pillaring by z
irconium oxide.