Synthesis, characterization, and catalytic properties of pillared montmorillonite with aluminum/cerium polyoxycations

This paper describes the preparation of pillared montmorillonite by means of mixed aluminum and cerium oligomers. When cerium was incorporated into the materials, the basal spacing increased up to 26 Angstrom. Nuclear magnetic resonance studies indicated total absence of tetrahedral aluminum in the polyoxycations incorporated between the clay sheets. These results indicate that AlCe-pillared montmorillonite incorporates inorganic polyoxycations with a chemical nature different from that of the aluminum polyoxycation or Keggin ion [AlO4Al12(OH)(24)(H2O)(12)](7+) The texture of the materials showed a high specific surface area and porosity, with generation of pores at the limit between the microporous and mesoporous zones. The number and strength of the acid sites in these materials were also high. The catalytic behavior of the materials in the hydrocracking and hydroisomerization reaction of n-heptane was compared with that of materials obtained from the same montmorillonite and intercalation of the Keggin ion. The AlCe-pillared samples showed increased conversion and improved the selectivity toward the products of cracking.