Silica-alumina-zirconia

As already published in the literature, sol-gel associated to supercritical drying always gives highly developed and divided materials which can have many applications in heterogeneous catalysis. Addition of a small part of Y2O3 to silica, alumina, zirconia, and titania revealed a beneficial effect on the thermal resistance of these materials. However, it is difficult to compare our results to those already published because in our work, the volumetric ratio of precursor to solvent (1/1) was much higher than the one generally used by other authors on the one hand, and on the other hand, we never added any catalyst, either acidic or basic, contrary to most of the works recently described in the literature. 

The early type of catalytic cracking units involved the use of a fixed-bed operation and this type of processing has been largely supplanted by the fluid- and moving-bed types of operation. The catalysts are used in the form of powder, microspheres, spheres, and other preformed shapes. The catalysts employed are either synthetic silica-alumina composites or natural aluminosilicates. Other catalysts, such as silica-magnesia, alumina-boria, silica-zirconia, and silica-alumina-zirconia have found limited commercial application and, at present, the synthetic silica-alumina and natural clay catalysts dominate the field. 

Catalytic Cracking of Hexadecane Temperature 500°C. Catalyst silica-alumina-zirconia Pressure atmospheric Process Period 1 Hour... 

Yan XM, Kwon S, Contreras AM, Koebel MM, Bokor J, Somoijai GA (2005) Fabrication of dense arrays of platinum nanowires on silica, alumina, zirconia and ceria surfaces as 2-D model catalysts. Catal Lett 105 127-132... 

Most particulate nanocrystals are inorganic oxides such silica, alumina, zirconia, halfnia, and titania. 

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