Page 168 - Principles of Catalyst Development
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156 CHAPTER 7
GAS A A + B
GAS B B + A
Figure 7.19. Wicke-Kallenback method for measuring diffusivity.
applicable, but extrudates, spheres, irregular particles, and used or distorted
particles are not.
A technique that overcomes these limitations is based on the principles
of chromatography, as shown in Fig. 7.20.(218) The catalyst, in any form, is
packed in a tube. A pulse of argon, injected into helium carrier gas, is
He ... Ar PULSE
L
THERMAL
CONDUCTIVITY ----J
CELL
INLET PULSE
CATALYST
BED
DIFFUSED PULSE
f<'igure 7.20. Chromatographic method for measuring diffusivities.
