Controlled Architecture of Solids With Micro-porosity and Meso-porosity Obtained By Pillaring of Montmorillonite With An Laniox Binary Oxide

High-surface-area solids containing both micropores and mesopores have been synthesized by intercalation of the heterobinuclear cation of the complex NiLa(fsaen)NO3 between the layers of montmorillonite clay and calcination at 500-degrees-C. The adsorption mechanism of the complex follows an exchange reaction involving up to 2 mmol of complex cations per g of clay. Further amounts of complex are adsorbed in sites other than exchange ones as shown by zeta-potential experiments. The IR spectra of the intercalated complex showed no major alterations of the complex during adsorption and a stabilization effect and enhancement of the parallel orientation of the clay plates. X-Ray diffraction (XRD) measurements at low angles showed that the pillared clay possesses an interlayer distance of 13.4 angstrom at 500-degrees-C. Its BET surface area reaches a maximum of 220 m2 g-1 at this temperature. The a(s) plots showed a maximum microporosity at less-than-or-equal-to 2 mmol g-1 Additional loading results in transformation to a mesoporous delaminated structure. X-Ray photoelectron spectra (XPS) of the composite materials showed that the ratios La/Si and Ni/Si are lower than those determined by chemical analysis, owing to the shielded environment of the LaNiO(x) pillars in the clay. The same method indicated that for a high degree of loading the aggregates seem to be of perovskite origin

Synthesis, characterization and catalytic activity of LayMOx (M=Ni, Co) perovskite-type particles intercalated in clay via heterobinuclear complexes

Clays intercalated with LayMOx (M = Ni, Co) nanospecies with perovskite-type structure have been prepared from heterobinuclear complexes MLa(fsaen)NO3, LaM(H2L)(NO3)(3), and [LaML(NO3)](2). The cationic form of these binuclear complexes was introduced between the clay sheets via an exchange process and a d-space of 17.7-24.8 Angstrom was achieved. After heating and removal of the organic part LayMOx nanospecies were formed and the d-space was around 12.3-14.0 Angstrom. The specific surface area of the fired solids was found to be between 92 and 178 m(2) g(-1), depending on the method of preparation used. The products were investigated by XRD; TG/DTA, specific surface area and acidity (Bronsted/Lewis) measurements, as well as by EDX analysis for their composition. Their catalytic activity was evaluated in the reaction of isopropanol and cracking/isomerisation of heptane. These solids showed essentially dehydrating activity in isopropanol decomposition, and hydrogenolytic activity in heptane reaction. The extent of catalytic conversion for the isopropanol decomposition for the intercalated materials was lower as compared to non-intercalated samples. The conversion for the heptane hydrogenolysis reached similar to 100% at similar to 350 degrees C and proceeds mainly towards cracking rather than isomerization which reached only similar to 8%. (C) 1998 Elsevier Science B.V. All rights reserved