Nanocrystalline Cu-ZnO-based catalysts were successfully synthesized via a homogeneous precipitation method. Four aging times were used to prepare the catalysts (1, 3, 12 and 24 h) to study the influence on their textural, structural and catalytic properties. The samples were characterized by N 2 adsorption, powder X-ray diffraction, thermogravimetric analysis, H 2 temperature-programmed desorption and transmission electron microscopy, and the samples were applied to the steam reforming of methanol. The crystallinity and purity of the aurichalcite phase precursor was enhanced after 3 h of aging. Structural changes were observed in the calcined catalysts as the aging time increased. A decreased CuO crystallite size was produced at longer aging times, which enhanced the CuO dispersion and Cu-ZnO interactions. These factors affected the catalytic activity. The catalyst aged for 24 h showed the highest methanol conversion, and a correlation between the structure and activity was verified.

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Zeolite-supported metallic catalysts are very important in the chemistry industry, especially in naphtha related reactions such as dehydrogenation of naphthenics to aromatics and paraffin hidroisomerisation. In the Pt/KL-zeolite catalyst the size and dispersion of the metallic particles are fundamental parameters for its performance [1,2]. Different methods of metal introduction are employed to achieve the desired properties. In the present work, samples prepared by ionic exchange (IE) and wet point impregnation (WPI) were analyzed.The metallic particles are nm-sized and thus TEM is required for their characterization [2]. However, as shown in Figure 1, it is not an easy task to discriminate the particles in a TEM image, due to the strong changes in contrast that result from the varying thickness of the zeolite support.