(567d) Additive Manufacturing for Process Intensification: Tailor-Made Design of Catalyst Supports for Single Phase and Multiphase Reaction Systems

Open cellular
structures are promising novel catalyst supports as they combine the advantages
of randomly packed fixed-bed reactors (radial mixing, tortuosity of the flow)
and honeycombs (high geometric specific surface area, low pressure drop) owing
to their high porosities and their characteristic 3D cellular architecture.
Open cellular structures are manufactured mainly by means of a replication
technique, which results in an irregular architecture of the structure, and
consequently of the open porous system.

With the rise of
additive manufacturing techniques it is nowadays possible to manufacture
periodic open cellular structures (POCS) by, e.g., selective electron beam
melting (SEBM) with well-defined geometrical properties. In this regard, a new
degree of freedom in the design is unlocked as metal-based open cellular
structures of nearly arbitrary geometrical complexity can be manufactured in a
well-defined and highly reproducible manner.

We have extensively
investigated open cellular materials with both periodic [1,2] and random [3]
cell geometries regarding their performance as catalyst support. These
structures were characterized with respect to their morphological/geometrical
properties, fluid dynamic behavior and mass and heat
transport properties. Models for the estimation of properties important for
reactor design such as, e.g., specific surface area and pressure drop [1, 2]
were developed and validated by experiments.

Detailed
numerical studies of such geometries and the 3D flow field along with mass and
heat transport processes as well as studies on the effective heat conductivity
in POCS of different configurations were carried out [3, 4]. The established
models allow for the design and optimization of POCS that are tailor-made
according to the needs of the reaction system, representing a new class of
superior catalyst supports.

The tailor-made
POCS were manufactured, functionalized by catalytic coating, and then applied
in two case studies for demonstration. In the first case study, the focus is on
the optimization of heat transport in a highly exothermic gas phase reaction
for enhancing the selectivity, where the oxidation of methanol to formaldehyde serves
as example system. In the second case study the phase contacting, i.e. the
gas-liquid distribution in a trickle-bed reactor was optimized [5]. As example
reaction system, the hydrodesulfurization (HDS) of
gas oil was investigated.

For both reaction
systems, the tailor-made POCS were benchmarked against a traditional randomly
packed bed reactor, and clearly a great potential for process intensification
could be demonstrated.

References

[1]       Inayat, A.; Schwerdtfeger, J.;
Freund, H.; Koerner, C.; Singer, R.F.; Schwieger, W.;
Chem. Eng. Sci. 66(12) (2011) 2758-2763.

[2]       Klumpp, M.;
Inayat, A.; Schwerdtfeger,
J.; Koerner, C.; Singer, R.F.; Freund, H.; Schwieger,
W.; Chem. Eng. J. 242 (2014) 364-378.

[3]       Bianchi,
E.; Groppi, G.; Schwieger, W.; Tronconi,
E.; Freund, H.; Chem. Eng. J. 264 (2015) 268-279.

[4]       Bianchi,
E.; Schwieger, W.; Freund, H.; Adv. Eng. Mater. 18(4) (2016) 608-614.

[5]       Laemmermann, M.; Schwieger,
W.; Freund, H.; Catal. Today 273 (2016) 161-171.