3 Continuous-Flow Reactions Using Metal Nanoparticles
Packed in Columns (Fixed-Bed Reactors)
Microreactors have advantages of high interfacial specific surface area for
multiphase reactions; however, the productivity of a single microreactor is low.
Although increasing the number of single microreactors increases the productivity,
this approach is expensive. The most straightforward and cost-efficient method for
continuous-flow reactors using a heterogeneous catalyst on a lab to industrial scale is
using a column packed with appropriate heterogeneous catalyst as the reactor. When
finely powdered heterogeneous catalysts are packed into a column and both gas and
liquid are streamed, the heterogeneous catalyst itself can work as a “mixer” of the
two phases, and efficient mixing and large interfacial surface area can be expected.
The speed of each stream, the physical properties of the solid catalyst, and the design
of the inlet of the column can be very important to achieve both efficient mixing and
smooth streams of both phases.
N
n
2
(PdCl 2 )n
composite 5a
µ-device 6a
aq. HCOONa
50 ºC, 0.5 h
a)
b)
N
n
2
(PdCl 2 )n
composite 5b
µ-device 6b
aq. HCOONa
50 ºC, 0.5 h
5n
HN
O
c)
n
(PdCl 4 ) 2composite 5c
µ-device 6c
aq. HCOONa
50 ºC, 0.5 h
N
N
Fig. 9 Preparation of Pd nanoparticle membrane in a microflow reactor
218
H. Miyamura and S. Kobayashi