Chemical Engineering August 2016 - 40

Microreactors:
Lessons Learned From
Industrial Applications
Implementing microreactors in chemical production is quite a challenge. How these challenges
can be met is described here
Raf Reintjens
and André de
Vries
DSM
IN BRIEF
PROCESS
INTENSIFICATION AS AN
ENGINE FOR INNOVATION
BASIC PRINCIPLES
DYNAMICS OF
INNOVATION
HURDLES TOWARDS
INDUSTRIAL
APPLICATION
AN APPROACH TO
CROSS THE CHASM
MANUFACTURABILITY
VERSUS PERFORMANCE
DESIGN STRATEGIES
THE IMPACT OF ADDITIVE
MANUFACTURING
CONCLUDING REMARKS
A
t the heart of
a chemical
process is
the reactor,
where the conversion
of reactants to products
occurs. Depending
on the need for
efficiency or flexibility,
the chemical process
industries (CPI) optimize
their processing
" solutions " towards
continuous, worldscale
plants for bulk
Try it!
Technology
enthusiasts
(innovators)
Visionaries
(early
adopters)
* Easy to convince
* Just being new
Stick with the
herd!
Get ahead of
the herd!
Chasm
valley of death
Pragmatists
(early
majority)
* Difficult to convince
* Must work properly
FIGURE 1. The critical point in the adoption of a high-tech innovation is reached when the
early majority needs to be convinced of their adoption decision by proven feasibility (y-axis is
percentage of adopters)
chemicals, or to batch operated, multi-product
plants for complex fine chemicals. The
struggle to stay competitive and deliver high
quality product at low cost drives the industry
towards the use of increasingly largerscale
reactors. This economy-of-scale principle
helps to lower the cost level, but also
imposes serious limitations on mass- and
heat-transfer, often resulting in moderate
space-time yield or productivity.
PI as an engine for innovation
Process intensification (PI) takes a different
approach to optimizing reactions. When looking
at the underlying fundamental physical
and chemical processes and fluxes that occur
during a chemical conversion, we can define
an " optimal pathway " for the molecules [1, 2].
The aim is to fulfill the needs of the reaction,
in the sense of bringing reactant molecules
together in the right stoichiometry at the right
time and extracting the released reaction
enthalpy in a perfect way to avoid overheating
and selectivity loss. The virtual absence
of concentration and temperature gradients,
combined with near to ideal plug flow, would
ensure that every product molecule experi40
ences
the same processing history.
By increasing the temperature, we could
accelerate the rate of reaction and explore
ever higher productivity levels. Of course,
the " landscape " of possible chemical pathways
would still require delicate navigation
to avoid unwanted consecutive or side reactions
and maintain sufficient chemical selectivity.
In the end, when we could design
this ideal reactor that allows us to follow
the " optimal pathway, " the limitation to the
productivity increase would come from the
chemistry itself rather than the capabilities
of the reactor.
The approach of PI towards improving cost
efficiency, boils down to maximizing the performance-to-cost
ratio. The volumetric cost
level of an intensified reactor may exceed that
of conventional reactors due to increased
complexity. But as long as the productivity
gain is more than proportional, the net cost
per unit of production capacity will go down.
Basic principles
Over the past decades, the use of microreactors
in chemical synthesis became the
subject of many papers [3, 4]. LaboratoryCHEMICAL
ENGINEERING WWW.CHEMENGONLINE.COM
AUGUST 2016
Conservatives
(late majority)
Skeptics
(laggards)
Hold on!
No way!
http://WWW.CHEMENGONLINE.COM
Chemical Engineering August 2016

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