Halloysites as tubular alumosilicates are introduced as inexpensive natural nanoparticles to form and stabilize oil–water emulsions. This stabilized emulsion is shown to enable efficient interfacial catalytic reactions. Yield, selectivity, and product separation can be tremendously enhanced, e.g., for the hydroformylation reaction of dodecene to tridecanal. In perspective, this type of formulation may be used for oil spill dispersions. The key elements of the described formulations are clay nanotubes (halloysites) which are highly anisometric, can be filled by helper molecules, and are abundantly available in thousands of tons, making this technology scalable for industrial applications
The
implementation of the hydroformylation reaction for the conversion
of long-chain alkenes into aldehydes still remains challenging on
an industrial scale. One possible approach to overcoming this challenge
is to apply tunable systems employing surfactants. Therefore, a novel
process concept for the hydroformylation of long-chain alkenes to
aldehydes in microemulsions is being investigated and developed at
Technische Universität Berlin, Germany. To test the applicability
of this concept for the hydroformylation in microemulsions on a larger
scale, a miniplant has been constructed and operated. This contribution
presents the proof of concept for hydroformylation in microemulsions
carried out during a 200 h miniplant operation. Throughout the operation
a stable aldehyde yield of 21% and a catalyst loss in the product
phase below 0.1 ppm were achieved, which confirms previous lab scale
findings. Additionally, solution strategies for a stable continuous
operation to overcome challenges such as foaming, phase separation
issues, and coalescence dynamics are discussed herein.
We investigate aqueous multiphase
systems for catalytic gas/liquid
reactions, namely, the rhodium-catalyzed hydroformylation of the long-chain
olefin 1-dodecene. The multiphase system was formulated from 1-dodecene,
water, and a nonionic surfactant, which increases the solubility between
the two nonmiscible liquid phases. On the basis of these systems,
we present in this paper a transfer of lab experiments (semibatch)
to a successful operation of a miniplant in continuous mode. Under
optimized conditions, the reaction showed turnover frequencies of
∼200 h–1 and high selectivity of 98:2 to
the desired linear aldehyde. The miniplant was operated continuously
for a total of 130 h. The control of the phase separation and catalyst
recycling for product isolation for a long time period appeared to
be challenging. Nevertheless, the separation was kept stable for over
24 h. The organic components in the product phase amounted to desired
values between 95 and 99 wt %. The desired 99.99% of the catalyst
remained in the aqueous catalyst phase.
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