Page 137 - Principles of Catalyst Development
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CATALYST PREPARATION 125
Each step in the recipe must be translated into large-scale operation.
First, each must be technically feasible, that is, engineering counterparts
must exist for laboratory procedures. Equipment is usually no
problem, (35,160) but maintaining the controlling conditions may be, Second,
scale-up must be economical. The most important factor here is capital
investment to acquire facilities for what may be large quantities. Purity
levels of reagents is another issue which requires attention. Large quantities
of very pure feedstocks may be expensive or even unattainable.
Equipment is usually available or adaptable for most steps. Table 6.4
list common unit operations found in catalyst manufacturing. Many are
material treating methods used by the solid or mineral processing industries.
Relative difficulties in scale-up have already been touched upon; for
example, drying is usually easier, precipitation harder.
6.7.2. Continuous Unit Operations
As in all chemical processing, continuous operation is much more
satisfactory for large throughputs. Operating costs are lless and product
quality control better. Whenever possible, the catalyst manufacturer
attempts to modify preparational procedures to accommodate continuous
operations. This is fairly straightforward for filtering, drying, calcination,
TABLE 6.4. Unit Operations in Catalyst Manufacwring
Preparation step Unit equipment
Precipitation Tanks, batch and semi batch
Mixing tanks
Jets
Filtering Leaf
Rotary
Centrifugal
Drying Trays
Forced air
Moving belts
Rotary kilns
Fluidized beds
Spray driers
Calcination Forced air furnace
Rotary kiln
Fluidized beds
Formulation Pelleting
Extrusion
Spheroidization