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Requirements for the Carrier Materials

The first step was the choice of suitable carrier materials. Supports with pores in the nanometer range were discounted, mass-transfer limitations could occur. The task is to incorporate fine polymer particles into the pore volume of the carrier. Polymer particles from known preparation methods are rather large, so this also requires large pores. The requirements for a suitable carrier material are given in Table 8.2.

Table 8.2 Desired properties of the carrier materials

Large pore volume

Open, interconnected pores

Large pores in the micrometer range

High mechanical strength

Inert in the polymerization step

Stability during all preparation steps

Suitable materials are ceramics and glass. In principle natural materials are also possible, for example pumice. That would be a very cheap material, but natural minerals could contain ions that could interfere with the active sites of the incorporated resin. So this is not a good material choice. In Table 8.3 a compilation of selected materials is given.

The pore diameter covers a wide range and is larger than for standard catalyst supports; such materials are called 'megaporous' [22].

Table 8.3 Selected carrier materials suitable for the preparation of polymer/carrier catalysts

Carrier material

Shape

Pore diameter

Pore volume

Mullit ceramic

structured packing

0.15 ^m

35%

Porous glass

Raschig ring 9 mm

60-300 ^m

55-60%

Alumina foam

X-size 2 X 1 X 1 cm

0.1 mm

85%

Glass foam

Irregular pieces 2 cm

0.2 mm

75%

Silicon carbide foam

Irregular pieces 2 cm

1.5 mm

80%

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