(325d) Development of a Short-Cut Model for Three-Phase Liquid Separation Dynamics for a Hydroformylation Mini-Plant | AIChE

(325d) Development of a Short-Cut Model for Three-Phase Liquid Separation Dynamics for a Hydroformylation Mini-Plant

Authors 

Müller, M., Berlin Institute of Technology


Development of a Short-Cut
Model for Three-phase Liquid Separation Dynamics for a Hydroformylation
Mini-Plant

David Müller*, Erik Esche**, Michael
Müller***, Günter Wozny****

Chair of Process
Dynamics and Operation, Berlin Institute of Technology, Sekr. KWT-9, Str. des
17. Juni 135, D-10623 Berlin, Germany

Corresponding author: *david.mueller@tu-berlin.de,

**erik.esche@tu-berlin.de, ***m.mueller@tu-berlin.de,****guenter.wozny@tu-berlin.de

Within the
framework of the Collaborative Research Centre SFB/TR 63 InPROMPT, ?Integrated chemical processes in
liquid multiphase systems?, a novel process concept for the
hydroformylation of long chain alkenes in micro emulsions is investigated and
developed at Berlin Institute of Technology (Technische Universität Berlin), Germany. In industry, hydroformylation is an
important application in the field of homogenous catalysis and has been
established as a standard process for the production of short-chained aldehydes
from alkenes. The application
for higher alkenes (longer
than C12) on the other hand, has not yet been established.

The investigated
novel process concept sees opportunities for the continuous hydroformylation of long-chained alkenes in the
creation of a micro emulsion system. Through the application of a
surfactant this micro emulsion system can be formed and the hydrophilic rhodium-ligand-complex catalyst
required for the reaction can be brought into contact with the alkene. The
reaction itself is initiated by injecting syngas (H2&CO) into
the micro emulsion system formed in a continuously stirred tank reactor. After
the reaction, due to the phase separation into an aqueous (catalyst-rich), an
emulsion (mixed), and an organic (product-rich) phase, the valuable rhodium
catalyst is separated and recycled. To investigate and
optimize the described process concept, a mini-plant is built at Berlin
Institute of Technology.

Figure 1: Novel process concept for the hydroformylation
of long-chained alkdehydes.

The crucial aspects of the concept with
regards to technical and economic feasibility are the separation steps to
recycle the rare and expensive catalyst. Since there is barely any thermodynamic data on the
system available, the temperature and concentration sensitity proves to be a
challenging issue. The goal of
this contribution is to develop a model of the three-phase liquid separation
dynamics for the temperature control of the decanter. Thus, the quality of the phase
separation can be adjusted accordingly.

The solution
approach is divided into several steps. Firstly, experiments in graduated test
tubes for various concentrations and temperatures are performed and the height
of each of the phases is measured over time. The idea is that the optimal
separation time at a certain temperature indirectly represents the necessary
length in a horizontal flow decanter, which can be adjusted by manipulating the
superficial velocity of the inlet stream. In the second step, the previously
obtained results are used to derive a polynomial function to estimate the
heights of each of the three phases hj: hj = f(t, T, ci).
These are dependent on time t, the temperature level T, and the concentrations
of alkenes, aldehydes, surfactant, and catalyst. Furthermore, the switch from
3-phase to 2-phase systems is included through the intersection of two
polynomials describing the phase interfaces. Thirdly, an experimental set-up
with a glass replication of the actual decanter in the mini-plant is used to test
the validity of the determined results from the test tubes for the decanter.

As a next step,
adjustments to the derived equations are made to incorporate the pressure
dependency of the system. Afterwards, the results are implemented in the
mini-plant allowing for an effective temperature control. Hence, through the determined
model the optimal operation conditions can be maintained in the mini-plant and
a step towards economic feasibility is taken.

Acknowledgment

                This work is part of the Collaborative Research Centre
"Integrated Chemical Processes in Liquid Multiphase Systems"
coordinated by the Technische Universität Berlin. Financial support by the German
Research Foundation (Deutsche Forschungsgemeinschaft, DFG) is gratefully acknowledged
(TRR 63).

See more of this Session: Best Practices In Pilot Plants

See more of this Group/Topical: Process Development Division