Preparation and Characterization of Hydroxy-FeAl Pillared Clays

Dongyuan Zhao1, 2, Guojia Wang2, Yashu Yang3, Xiexian Guo3, Qibin Wang4 and Jiyao Ren4
2 Department of Chemistry, Jilin University, Changchun 130023 P.R. China
3 Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, P.R. China
4 Department of Fine Chemical Technology, Shenyang Institute of Chemical Technology Shenyang 110021, P. R. China
1 Present address: Department of Fine Chemical Technology, Shenyang Institute of Chemical Technology, Shenyang 110021, P. R. China.

Abstract: Solutions containing hydroxy-FeAl oligocations (HFA) were prepared by two procedures: (1) treatment of a mixture of FeCl3 and AlCl3 with aqueous Na2CO3, followed by aging of the product and (2) preliminary preparation and aging of hydroxy-Al13 oligocations followed by reaction of the latter with aqueous FeCl3. Ion-exchange of Na-montmorillonite with HFA yield pillared clay (designated as FeAl-PILC) with d(001) values of 1.98–1.56 nm and a surface area of 230 m2/g. The pillar structure, thermal stability, surface acidity, and reduction behavior of the pillared clays were determined by 27Al-NMR, XRD, DTA, Mössbauer spectroscopy, Py-IR, TPD, TPR. Fe/Al ratios greatly affect the pillar structure, surface area and thermal stability of FeAl-PILC. The pillar in FeAl-PILC with Fe/Al ratio <0.5 has a Keggin structure, similar to that of Al-PILC, but the pillar structures of FeAl-PILC with Fe/Al ≥0.5 are the ferric tripolymer species similar to those of Fe-PILC. The basal spacings, surface area, and thermal stability are decreased with increasing Fe/Al ratio. There is relatively strong interaction between Fe and Al in the pillars. The interaction is enhanced with decreasing Fe/Al ratio. Reduction of the Fe phase in FeAl-PILC was reduced by the interaction of Fe with Al.

Key Words: Acidity • Hydroxy-FeAl pillars • Pillared clay • Preparation • Stability

Clays and Clay Minerals; June 1993 v. 41; no. 3; p. 317-327; DOI: 10.1346/CCMN.1993.0410306
© 1993, The Clay Minerals Society
Clay Minerals Society (www.clays.org)