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The nanostructured lanthanide-silica materials of the Ln–SiO2 type (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu) were synthesized by the hydrothermal method at 100 °C, using cetyltrimethylammonium as a structural template, silica gel and sodium silicate as a source of silicon, and lanthanide oxides, with Si/Ln molar ratio = 50. The resulting materials were calcined at 500 °C using nitrogen and air, and characterized by X-ray diffraction (XRD), Fourier-Transform infrared absorption spectroscopy, scanning electron microscopy, thermogravimetry (TG), surface area by the BET method and acidity measurements by n-butylamine adsorption. The XRD and chemical analysis indicated that the SiO2 presented a hexagonal structure and the incorporation of lanthanides in the structure changes the properties of the Ln–SiO2 materials. The heavier the lanthanide element, the higher the Si/Ln ratio. The TG curves showed that the decomposition of the structural template occurs in the materials at temperatures below 500 °C. The samples showed variations in specific surface area, mean pore diameter and silica wall thickness, depending on the nature of the lanthanide. The incorporation of different lanthanides in the silica generated acid sites of varied strength. The hydrothermal stability of the Ln–SiO2 materials evaluated at high temperatures, evidenced that the properties can be controlled for application in adsorption and catalysis processes. [ABSTRACT FROM AUTHOR]

The preparation, characterization and application of materials based on montmorillonite natural clay containing aluminum polyhydroxocomplexes of Keggin type ions (Al13) as intercalating agent and hydrated lanthanum complexes were carried out. The introduction of Al and La inside the interlayer space increased the basal distance d(001) of the clay. The evaluated materials, designed as Natural Montmorillonite Clay (NMC), Al13-PILC and LaAl13-PILC were characterized by X-ray diffraction for evaluating the basal spacing of the clay, nitrogen adsorption for determination of the specific surface area and pore size of the materials and scanning electron microscopy, in order to observe the morphology. The catalytic activity was verified on the pyrolysis of Atmospheric Residue of petroleum (ATR), at temperature of 500 °C, in a micro-reactor coupled to gas chromatograph and mass spectrometry. The results showed that LaAl13-PILC material presented high catalytic activity for this process. The lanthanum preferably fills the interlayer space of the Al13-PILC, generating acid sites and therefore increasing the activity for ATR cracking. The obtained products were hydrocarbons in the range of light gases (C2-C4), gasoline (C5-C10) and diesel (C11-C20). This result is due the combination of porosity and acid properties of the PILC samples. [ABSTRACT FROM AUTHOR]