Estudo da influência dos precursores sobre os catalisadores de Pd/Al2O3 promovidos com céria ancorado sobre a alumina. A oxidação do propano foi feita sob diferentes condições de alimentação sendo caracterizados os sítios superficiais por Espectroscopia Fotoeletrônica de raios X (XPS) e por Refletância Difusa em ''situ''. Resultados de XPS e DRS mostraram a formação de interfaces de PdO/Pd0 como sendo os sítios ativos, independentes do precursor utilizado na preparação, enquanto que os catalisadores contendo CeO2 mostraram a formação de espécies de paládio com estado de oxidação mais altos, provavelmente PdO2 (338 eV) após a oxidação do propano. Além disso, as razões O/Al e O/Ce evidenciaram um aumento de oxigênio armazenado na presença de CeO2. O precursor acetilacetonato favoreceu o armazenamento de oxigênio na rede.

The influence of the precursors on the promoting effect of ceria on Pd/Al2O3 catalyst, when ceria is coated over alumina was studied. The reaction of propane oxidation proceeded under different feed conditions and the surface active sites were characterized by X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance spectroscopy (DRS). XPS and DRS results show that PdO/Pd0 interface are the active sites independent of the precursor, while the catalysts containing CeO2 showed formation of palladium species in the highest oxidation state, probably PdO2 (338 eV) after the oxidation of propane. Besides, the O/Al and O/Ce ratios evidenced the increase of oxygen storage in the presence of CeO2. In addition, the precursor acetylacetonate favors the oxygen storage in the lattice.

Al-pillared clay was prepared with a Brazilian bentonite from the Campina Grande region (Paraíba, BRAZIL). It was intercalated at 298 K, during 48 hours, with a solution containing [Al3+] = 0.10 mol/L and molar ratio OH/Al = 2.0 prepared at 333 K, and was calcined at 773K. The catalytic activity was evaluated by alkylation of benzene with 1-dodecene. The characterization methods were: X-ray fluorescence and diffraction analysis; 27Al, 29Si and 23Na MAS NMR and textural analysis by N2 adsorption. The thermal stability of the natural clay was improved by the pillaring procedure, as well as the catalytic activity. The intercalated clay presented the highest initial rate of reaction among the systems tested.