Reactor engineering

Heterogeneous manufacturing processes based on chemical reactions, biochemical transformations and adsorption, which inherently involve both a solid and a liquid phase, are associated with several technical challenges. One of the most difficult issues is achieving contact between the reagents in the two phases – a phenomenon known as mass transfer limitation. The reagents in the liquid phase must be brought to an active site on the solid phase through transport of the liquid medium relative to the solid particle. In absence of any stirring to create convective flow, this transport only takes the form of diffusion, which is a very slow process. The mass transport is therefore increased in laboratories and production facilities by means of a suitably designed reactor.

Reactor types

The traditional and perhaps most common way to deal with mass transport limitations is a stirred tank reactor (STR). In the STR a two-phase slurry of particles in suspension is stirred using an agitator. This generates a convective flow in the reactor which increases the relative transport of the liquid phase and solid particles, bringing reactants together at a higher rate than if left only to diffusion. The agitator also improves the mixing time of the reactor, being the time taken to disperse any concentration gradients in the liquid bulk that arise due to the local generation or removal of chemical species at the reaction sites. However, the STR may cause physical damage to the solid phase as the particles collide with the agitator and each other. These collisions often lead to grinding of the particles, producing fines that are hard to remove and limit the ability to reuse the solid material. For most applications, the STR thus introduces a need for filtration after the reaction is completed.

A gentler treatment takes place in a packed column, also known as a fixed bed reactor (FBR). Here the solid phase is packed in a stationary bed through which the liquid phase is then pumped. Grinding is then eliminated as there is no relative motion between any solid bodies. Still, associated with the FBR is a back pressure that increases with liquid viscosity and flow rate among other parameters. To avoid slow percolation of viscous liquids through the packed bed, powerful pumps and strong particles that can withstand immense pressures are required for operation of FBR.

Rotating bed reactors

A rotating bed reactor (RBR) is a modern alternative to the traditional reactor types. The solid phase is loaded into the RBR and kept in place by filters that allow the liquid medium to pass through. The RBR is rotated within the reaction vessel containing the liquid which then passes through the RBR due to inertial forces. By keeping the solid phase fixed within the RBR it is protected from grinding. The flow rate, controlled by the rotational speed, can also become many times greater than in a typical column of corresponding volume. This leads to significantly greater reaction rates in mass transport limited cases. Moreover, each fluid parcel will have many passages through the RBR, providing the reagents with plenty of time to react with the solid phase in applications limited by chemical kinetics. Since the solid phase is contained within the RBR it may also be regenerated or reused in-situ for another reaction step without any time-consuming filtration in between.

Application L1701
A novel hierarchically structured siliceous packing to boost the performance of rotating bed enzymatic reactors

Katarzyna Szymańska, Klaudia Odrozek, Aurelia Zniszczoł, Wojciech Pudło, and Andrzej B. Jarzębski Chem. Eng. J., 2017, 315, pp. 18-24.

Application 1012
Flexible deployment with the plug-in rotating bed reactor

The rotating bed reactor (RBR) is a combined tool for chemical transformations and liquid transfer operations, reducing or eliminating the need for external pumps. Filled with a catalyst or adsorbent, and rotated by a motor, the RBR brings the liquid to be processed in contact with the solid-phase at high flow rates. Due to the high flow rate generated, the RBR can not only treat the liquid in the reaction vessel, but also transfer it into the vessel for processing.

Application 1007
Automatic processes for efficient production

Automation of large-scale processes is often a requirement for economically viable chemical processes. The benefits of scale are best harvested at high throughputs and 24/7 operation. This leads to the demand for process automation, and the elimination of hands-on work.

Application L1704
Biocatalysis engineering: the big picture

Roger A. Sheldon and Pedro C. Pereira Chem. Soc. Rev., 2017, 46(10), pp. 2678-2691.

Application L1702
CFD modeling of flow and ion exchange kinetics in a rotating bed reactor system

Hilde Larsson, Patrick Alexander Schjøtt Andersen, Emil Byström, Krist V. Gernaey, and Ulrich Krühne Ind. Eng. Chem. Res., 2017, 56, 14, pp. 3853-3865.

Application 9005
Palladium catalyzed Suzuki couplings in a Mettler-Toledo EasyMax™ 102

Heterogeneous catalysis can be an effective tool for chemical synthesis, particularly in the discovery and development of pharmaceutical ingredients. The handling of these solid catalysts is sometimes challenging as it leads to more unit operations in the factory scale, as well as introduces additional work-up in the laboratory.

Application 1035
Dramatically improved deionization with a rotating bed reactor

Removing ions from liquids is common in industry and society. Ions are remediated in applications ranging from the production of pharmaceuticals to the treatment of communal waste streams. Likewise, the nuclear energy sector deals with the removal of ionic radioactive substances from water on a daily basis.

Application 1024
Decolourization more efficient in rotating bed reactor than in fixed bed reactor

A fixed bed reactor (FBR), also known as a packed bed reactor or column, is a traditional technology for processes such as adsorption or heterogeneous catalysis. Achieving the required level of purification or conversion means running the liquid through the reactor at a sufficiently low flow rate, and the throughput of a fixed bed reactor is therefore often limited.

Application 1006
Rotating bed reactor faster than stirred tank reactor for a mass transfer limited reaction

Mass transfer limited reactions can create problems for applications like the synthesis of chemical products or the manufacture of active pharmaceutical ingredients. Poor yields, high side-product formation or impractically long reactions are potential issues. Efficient reactor design can greatly improve the mass transfer and remove the limitation to a minimum.

Application 1004
High-viscosity applications made faster

Liquids with high viscosity create problems for heterogeneous applications in traditional reactors. Packed bed reactors (columns) suffer from huge back pressures, and stirred tank reactors (STR) exhibit reduced reaction rates due to poor mixing. Both issues lead to longer processing times and expensive operations.

Application 1030
Viscous solutions decolourized using a rotating bed reactor and a stirred tank reactor

Decolorization, pesticide remediation, catalysis, and many other applications involve dealing with viscous liquid that needs to be modified in some way. The rotating bed reactor presents an efficient way to treat viscous liquids, without the challenges of conventional reactors.

Application L1601
Deconstruction of Nordic hardwood in switchable ionic liquids and acylation of the dissolved cellulose

Valerie Eta and Jyri-Pekka Mikkola Carbohydr. Polym., 2016, 136, pp. 459-465.

Application 1033
Deionizing 7000 L of tap water using the SpinChem® RBR S100

The SpinChem® rotating bed reactor (RBR) S100, with a solid phase capacity of 100 L, was used to deionize 7000 L of tap water. The RBR S100 was operating at 160 rpm and filled with 36.5 L of mixed bed ion exchange resin. The results show that the RBR S100 can efficiently process large liquid volumes. As shown by the successful deionization, the performance of the RBR remains high even when it is partially filled, which proves the extreme robustness of the RBR technology.

Application 1021
Automatic loading and unloading of a production scale rotating bed reactor

The separation of a heterogeneous catalyst, an adsorbent, or an ion-exchange resin from a liquid product is a time-consuming unit operation that often makes the use of these materials impractical. The rotating bed reactor is a more efficient technology for deploying catalysts for manufacturing or adsorbents for purification.

Application 1003
Improving reactions in emulsions using a rotating bed reactor

When working with an emulsion (and particularly with a heterogeneous catalyst) the mass transfer between the phases is critical. Insufficient mixing leads to lower interfacial area per volume, and in turn to poor mass transfer across the phases.

Application 1029
Channelling effects common in columns removed with rotating bed reactors

Fixed bed reactors (FBRs), also known as packed bed reactors (PBRs), are frequently used for purification, ion-exchange processes, or heterogeneous catalysis. Though relatively easy to construct, they are tedious to charge with solids in an effective way. A poorly packed FBR is subject to channelling, where passages are formed in the bed. These passages offer less resistance to the liquid, which will preferentially travel through those regions. In this work, the robustness with respect to channelling of a packed bed reactor was compared to a rotating bed reactor (RBR) using computational fluid dynamics (CFD).

Application L1401
Enhanced mass transfer upon switchable ionic liquid mediated wood fractionation

Valerie Eta, Ikenna Anugwom, Pasi Virtanen, P. Mäki-Arvelaa, and Jyri-Pekka Mikkola Ind. Crops Prod., 2014, 55, pp. 109-115.

Application 1013
High-throughput systems for processing liquid products

As a tool for heterogeneous catalysis, or purification of liquids using materials like activated carbon, the rotating bed reactor provides high throughput capability frequently exceeding traditional technologies.

Application 1042
How large liquid volumes can a rotating bed reactor process?

Large volumes of liquid waste will often accumulate at industrial sites. It may be very time-consuming and resource-intensive to adequately treat these waste streams for release, so the problem often compounds over time.

Application 1016
In situ filling and emptying of rotating bed reactors

Video showing how a SpinChem® rotating bed reactor (RBR) was charged with solid particles, followed by draining and replacing the reaction liquid without escape of solids. Lastly, the solid phase was removed without opening the RBR. This procedure illustrates a concept for automatic handling of solid phases in production scale equipment without opening the reaction vessel.

Application 1037
In-tank deployment of large scale rotating bed reactor

How can this process be scaled up? This is perhaps the most important question to consider when developing a chemical process. If it cannot be done on large scale, all the time and resources invested in laboratory work will be unrewarded. Pumping liquids through massive columns or separating solids from a large batch can be unsurmountable challenges that bring a halt to a new project before it has even left the starting blocks.

Application Brochure
Mass transfer revolutionized

The SpinChem rotating bed reactor (RBR) can eliminate poor mass transfer in heterogeneous reactions during chemical syntheses and biotransformations, preserve catalyst activity, and facilitate recycling of solid phases. This brochure presents our technology and its applications.

Application L2117
Multi‐enzyme cascade reaction in a miniplant two‐phase‐system: Model validation and mathematical optimization

Jens Johannsen, Francesca Meyer, Claudia Engelmann, Andreas Liese, Georg Fieg, Paul Bubenheim, and Thomas Waluga AIChE J., 2021, 67(4), e17158.

Application 1001
How to find the optimal rotational speed when using a rotating bed reactor

Many heterogeneous processes are limited by mass transfer at typical laboratory or industrial conditions. When using a rotating bed reactor, the mass transfer is most easily controlled using the rotational speed.

Application L2112
Production of hydroxytyrosol rich extract from Olea europaea leaf with enhanced biological activity using immobilized enzyme reactors

Alexandra V. Chatzikonstantinou, Αrchontoula Giannakopoulou, Stamatia Spyrou, Yannis V. Simos, Vassiliki G. Kontogianni, Dimitrios Peschos, Petros Katapodis, Angeliki C. Polydera, and Haralambos Stamatis Environ. Sci. Pollut. Res., 2022, 29, pp. 29624-29637.

Application L1703
Reaction engineering of biocatalytic (S)-naproxen synthesis integrating in-line process monitoring by Raman spectroscopy

M. Aßmann, A. Stöbener, C. Mügge, S. K. Gaßmeyer, L. Hilterhaus, R. Kourist, A. Liese, and S. Kara React. Chem. Eng., 2017, 2(4), pp. 531-540.

Application L1606
Recent advances in whole cell biocatalysis techniques bridging from investigative to industrial scale

Jochen Wachtmeister and Dörte Rother Curr. Opin. Biotechnol., 2016, 42, pp. 169-177.

Application 1032
Rotating bed reactor for immobilized enzymatic reactions

This case study presents a lipase-mediated stereoselective acetylation of a racemic amine in a rotating bed reactor.

Application 1025
Soft alginate beads used in a rotating bed reactor

Stirred vessels tend to damage soft heterogeneous catalysts, like enzymes immobilized in agarose or alginate beads, with activity loss and tedious workup as consequence. In a fixed bed reactor, these materials are easily compressed by the pressure gradient, leading to a loss of flow rate. Overcoming these challenges opens up the possibility to use biocatalysis as a tool for greener processes and more sustainable manufacturing.

Application 1010
Rotating bed reactors completely avoid grinding of molecular sieves

When using of solid-phase catalysts or adsorbents in reactors, the physical degradation of the materials is a common problem. The traditional stirred tank reactor inflicts mechanical damage to the particles, which causes attrition, fines that are difficult to separate, and loss of the functionality of the solid-phase.

Application 1044
Simple scale-up using flexible reactors

Research and development quickly takes new directions, and the requirements on a laboratory may vary with every new project. Limiting yourself to equipment with a narrow scope of conditions and applications may become expensive, since new equipment must be acquired for anything out of scope. With budgets quickly consumed by other projects, the need for new equipment may mean significant delays and a reduced capability to take on emerging opportunities.

Application 1020
Reactor design supported by computational fluid dynamics (CFD)

The performance of a reactor for heterogeneous chemistry depends on the liquid flow it creates, and the mass-transfer rates it can achieve. Simulations help us investigate in high detail how a rotating bed reactor performs in any configuration.

Application 1009
Multistep synthesis or simultaneous extraction simplified in a rotating bed reactor

The synthesis of products, such as active pharmaceutical ingredients (APIs), often involves multiple steps using heterogeneous catalysts or adsorbents. Thus, the simultaneous use of multiple solid phases either during synthesis or downstream processing is frequently highly advantageous.

Application 1040
The importance of baffles in a reactor vessel

Can you use a rotating bed reactor (RBR) in any type of vessel? - Absolutely! Would the performance be higher with baffles in the vessel? - Definitely!

Application 1022
Transfer hydrogenation with catalyst recycling in a rotating bed reactor

Hydrogenation reactions using hydrogen gas are usually efficient and clean. Drawbacks are the safety issues of handling hydrogen gas, need for reactors made for pressurized reactions, and the necessity of vigorous stirring to make these solid-liquid-gaseous reactions work well.

Application 1041
Treatment of 7.5 m3 with a 50 L Plug-in System

A small rotating bed reactor (RBR) system deployed in an external loop to the customer’s regular reaction vessel. Even though RBR technique has been identified as offering advantages for a particular process, deploying it in an existing reaction vessel may prove difficult for practical reasons. This is were “plug-in” mode deployment of the RBR can offer a solution. The RBR and associated vessel is attached in an external loop by inlet and outlet connections to the regular vessel. The “plug-in” RBR system is typically small compared to the regular vessel. Alternatively, the RBR system can be deployed in a vessel → RBR → 2nd vessel mode. A proof-of-concept demonstration of an RBR in “plug-in” mode by a decolorization. The volume of the “plug-in” vessel is ca 0.7% of the regular vessel it is attached to.

Application 1043
Using a rotating bed reactor in different liquid volumes

Research and development quickly takes new directions, and the requirements on a laboratory may vary with every new project. Limiting yourself to equipment with a narrow scope of conditions and applications may become expensive in the long run. The need for new equipment may inflict delays and affect your capability to take on emerging opportunities.

Application 1050
Lipase-catalyzed hydrolysis in 750 L using a rotating bed reactor

Biocatalysis offers many benefits in the production of chemicals and active pharmaceutical ingredients. One major challenge has been the deployment of immobilized enzymes in an efficient way on large scale. The rotating bed reactor offers a convenient way to scale a biocatalytic process.

Application 1051
How the loading of solids influences reaction speed

Sometimes you don’t want to pack the entire rotating bed reactor full with your solid-phase material. Fully loading might simply be wasteful, or you may want to experiment with your reaction conditions. But how does the amount of solids in the rotating bed reactor influence the reaction performance? Can you use only 10% of the full capacity?

Application L2002
Determination of kinetics and equilibria of heterogeneously catalyzed gas-phase reactions in gradientless autoclave reactors by using the total pressure method: Methanol synthesis

Tapio Salmi, Kari Eränen, Pasi Tolvanen, J.-P. Mikkola, and Vincenzo Russo Chem. Eng. Sci., 2020, 215, 115393.

Application L2003
Pharmaceutical industry perspectives on flow chemocatalysis and biocatalysis

Laura Leemans Martin, Theo Peschke, Francesco Venturoni, and Serena Mostarda Curr. Opin. Green Sustainable Chem., 2020, 25, 100350.

Application L2111
Streamlining design, engineering, and applications of enzymes for sustainable biocatalysis

Roger A. Sheldon and Dean Brady ACS Sustainable Chem. Eng., 2021, 9(24), pp. 8032–8052.

Application L2311
New enzymatic reactor designs: From enzymatic batch to 3D microreactors and monoliths

Kim Shortall, Katarzyna Szymańska, Cristina Carucci, Tewfik Soulimane, and Edmond Magner In: Biocatalyst Immobilization, Foundations and Applications, 2022

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