Page 143 - Principles of Catalyst Development
P. 143
CATALYST PREPARATION 131
HEATED HYDROGEL
AIR
~
DRYING CHAMBER
MICROSPHERES
Figure 6.29. Production of powdered catalysts using spray drying.
between larger ones, reducing porosity and increasing pressure drop. Better
results are found with uniform sizes.
6.8.6. Powders
Fluidized bed and slurry reactors utilize catalysts directly in the form
of powders (50-500 IA-m) and microspheres (up to 1.0 mm). These are best
produced by spray-drying, as shown in Fig. 6.29. Hydrogel is sprayed
through nozzles into a heated zone. Drying and calcination occurs rapidly
as the small drops fall.
6.9. MECHANICAL STRENGTH
Formulation of particles is the final step in manufacturing and estab-
lishes the mechanical strength of the catalyst. This is an important engineer-
ing parameter and manufacturing methods should satisfy process
specifications. Catalyst particles are designed to withstand the following
types of mechanical stress:
