Characterization of pre-shaped zirconia bodies for catalytic applications

Literature indicates that application of zirconia in a supported dehydrogenation catalyst is viable. Textural and structural properties of commercial pre-shaped zirconia supports from various suppliers were characterized using electron microscopy, element analysis, nitrogen physisorption, mercury intrusion porosimetry and X-ray diffraction. Most zirconias are sufficiently pure (>97 %) and thermostable to be applied in supported catalysts. Specific surface areas as large as 10 m(2) g(-1) are stable at temperatures of about 850 degrees C. Specific surface areas up to about 30 m(2) g(-1) can be established by a thermal treatment in air at temperatures up to the operating temperatures of the dehydrogenation process. Steam treatment affects the texture differently from treatment in dry air: sintering proceeds more rapidly in the presence of steam. The preshaped supports show a porosity (about 50%) which is higher than that reported for zirconia powders with the same pore-size distribution (5%). Th is is advantageous, both in the catalyst preparation step and in the catalytic reaction. However, the pre-shaped supports exhibit some microporosity.