Page 156 - Principles of Catalyst Development

144 CHAPTER 7

HYDRAULIC
PRESS

CATALYST
PELLET

(a) (b)
Figure 7.5. (a) Axial and (b) radial crushing test for catalyst pellets

to all shapes, pellets, extrudates, and spheresY93) The recommended
apparatus is shown in Fig. 7.6. A cylindrical sample holder 5 cm in diameter
and 5 cm deep is filled with about 100 cm of catalyst particles. The catalyst
3
is dehydrated by heating in air at 200°C for three hours. A constant pressure
is applied, from 3 to 30 atm for one minute. After pressure application, the
bed is removed and sieved for fines, using the following U.S. Standard
Series mesh for each catalyst size: 0.8 mm-40, 1.6 mm-20, 2.5 mm-12,
and 6.S mm-4. The weight percent fines below the minimum size are
recorded. The experiment is repeated at different pressures to generate data
of the type in Fig. 7.7. The bulk crushing strength is taken as the pressure
necessary to produce one weight percent fines. ASTM tests showed excellent
reproducibility for results from one organization to another.(J93)

7.3.3.2. Loss on Attrition
This test simulates actual use by tumbling 100 g of catalyst in a drum
at 56 rpm, as shown in Fig. 7.8. Attrited fines less than 20 mesh in size fall

PISTON

CATALYST PELLETS

HYDRAULIC SYSTEM
Figure 7.6. Apparatus for bulk crushing strength.