A comparison of the experimentally determined values of the mass transfer coefficients and the values of the mass transfer
coefficients according to the relations mentioned in literature
has been made. It appeared that not internal mass transfer
(sample bed diffusion, estimated according to Bischoff [13]),
but external mass transfer is (partially) rate limiting at the experimental
conditions applied. Furthermore, it appeared that
the experimentally determined values for the external mass
transfer coefficient kdiff agree reasonably well (within 20%)
with the values obtained using the well-known theoretical
Ranz–Marshall relation (Eq. (20)) as given by Ranz and Marshall
[14]: