PRESSED BODIES BASED ON PYROGENOUSLY PREPARED ZIRCONIUM DIOXIDE, PROCESSES FOR THEIR PREPARATION AND THEIR USE

摘要

Molded, or pressed articles on pyrogenically produced zirconium dioxide are disclosed and having the following features: -outside diameter 2-15 mm -BET surface area per DIN 66 131 30-50 m2/g -total pore volume 0.3-0.8 ml/g -pore size distribution no pores < 10 nm, at - least 80% of the - pores in the range of - 10-70 nm diameter -crushing strength 40-300 N -composition at least 98% ZrO2, SiO2, - remainder Al2O3, and/or - HfO2. - These molded articles are manufactured by homogenizing pyrogenically produced zirconium dioxide with any one of kaolin, sugar, or urea, or mixtures while water is being added, by drying the mixture at a temperature of 80 DEG to 120 DEG C. and then comminuting it into a friable powder which then is pressed into molded articles which thereupon are annealed for 1 to 4 h at 600 DEG to 1,000 DEG C. The pressed articles are used as catalysts or as catalyst-carriers.