Investigation of Catalytic Properties of Immobilized Enzymes and Cells by Flow Microcalorimetry - Advances in Biochemical Engineering Biotechnology - page 75

dT D T D T r e (- D H r )

v kin

= = =

9422 h

(17)

5 5 52

dz D z Z w Ç C P

where Z is the length of the packed bed. All of the constant parameters can be
included in parameter a

Z e (- D H r )

a = (18)

98

w Ç C P

and Eq. (17) can be rewritten

D T r = ha v kin (19)

or

D T r = a v obs . (20)

4
Transformation of Thermometric Data to Reaction Rates

The typical feature of the FMC is that the thermometric signal, T r ,and not the

true value of reaction rate is measured.In the approach of differential beds,the-
re is, however, a linear relation between

D

D T r and the overall reaction rate, v obs

[Eq. (20)].This means that - if the value of is known - reaction rate values can

be calculated from the measured temperature changes using Eq. (20) in the form

a

D T r

v obs = (21)

7

a

When the experimental data are available as a relation between overall reaction
rates and reaction conditions, they can be treated by procedures based on the
solution of mass balance equations, and the kinetic parameters can be deter-
mined, for example, by regression methods. The basic task that remains is to
determine the value of the parameter There are three possibilities to do this:

- calculation from its definition [Eq. (18)],
- calibration based on the investigation of the relation between

a.

T r and the
reaction rate determined by the post-column analysis of the concentration of
one of the reactants or by the measurement of the reaction rate in an inde-
pendent reaction module [28],
- the microcalorimeter autocalibration procedure explained below.
The disadvantage of the first approach is the requirement to know the quantities
involved in the energy balance (e.g.molar reaction enthalpy,fluid heat capacity
etc.).This disadvantage is eliminated by approaches based on calibration of the
microcalorimeter. Moreover, calibration can compensate for small systematic
errors produced by the microcalorimetric equipment, as well. In the second
approach, however, the post-column analysis of reactant concentrations by an

D