Synthesis and Characterization of Novel Zr-Al2O3 Nanoparticles Prepared by Microemulsion Method and Its Use as Cobalt Catalyst Support for the CO Hydrogenation Reaction

For the first time binary Zr-Al oxide nanoparticles were synthetized by coprecipitation in water-in-oil microemulsion. For comparison, a similar material was prepared by Zr impregnation on commercial alumina. After calcination, these materials and unpromoted alumina were used as cobalt catalyst supports to study and compare their structural characteristics and catalytic behavior in CO hydrogenation reaction. The supports and final cobalt catalysts were characterized by X-ray diffraction (XRD), N2 physisorption, scanning and transmission electron microscopy (SEM and TEM), temperature programmed reduction (TPR) and H2 chemisorption. The material synthetized by microemulsion (Zr-Al2O3 (ME)) presented homogeneous nanoparticles with highly dispersed zirconium, textural porosity with narrow pore size distribution and high surface area. On the other hand, the material prepared by Zr impregnation on Al2O3 (Zr-Al2O3 (IM)) produced a nonhomogeneous material with low Zr distribution and structural porosity. The cobalt deposition on these supports seems to be affected by the presence of zirconium. In the presence of highly dispersed Zr on alumina, the cobalt interaction with the support is higher. On the other side, the presence of ZrO2 islands on alumina avoids the cobalt-support interaction favoring the cobalt reduction degree, which makes a more active catalyst in the tested reaction. The final catalysts were tested in CO hydrogenation, and a higher CO conversion was obtained with increased Co° availability on the catalyst surface. Furthermore, the selectivity was affected by the CO conversion and the physico-chemical properties of the catalyst. This study gives highlights on the synthesis of highly uniform bimetallic nanoparticles used as support for cobalt catalysts and their application.