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
Chemical Catalysis with MagRBR and EasyMax – Quick and Convenient Suzuki couplings

This application note demonstrates how the combination of a SpinChem MagRBR custom-filled with heterogenous Pd(II)-catalyst and the controlled conditions in a Mettler-Toledo EasyMax™ 102 Advanced Synthesis Workstation allows for quick and convenient generation of C-C coupled products.  Keywords: Chemical catalysis, Easy handling, Mettler-Toledo

Application 1035
Column vs RBR

A performance comparison between a column (fixed bed reactor) and rotating bed reactor (RBR) for de-ionizing 1000 L of tap water. Using best-in-class standard protocols for both technologies, we tested which technology could de-ionize to a desired endpoint conductivity value the quickest. The result show that the RBR is significantly faster, reaching 3.7 times faster a conductivity level of 0.15 µS/cm compared to the column.  Keywords: Cleantech, Deionization, Fast reaction, Technology  

Application 1024
Decolourization more efficient in rotating bed reactor than 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.  Keywords: Ion exchange, Seamless scaleup, 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.

Merry Christmas
Effective extraction of spices for mulled wine production using a rotating bed reactor

Video showing how to promote holiday spirit by seasoning mulled wine using a rotating bed reactor. Assorted spices and sugar were used to transform white wine mixed with a clear liquor into a festive and flavourful Christmas drink. The temperature of the mixture was kept at 70°C and the outside temperature at -6°C, using a heating jacket and a northern latitude, respectively.  Keywords: Behind the scenes

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 for the liquid phase, which will preferentially travel through those regions. In this document, 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.

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 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.  Keywords: Easy handling, Seamless scaleup, Technology

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

To further demonstrate the use of RBR:s at process scale, a decolorization using ion exchange resin was performed at 7500 L scale. An RBR S14 was filled with strongly acidic cationic resin NRW1160 from Purolite and used to remove blue dye from an aqueous solution in a stainless steel tank of 7500 L volume. The solid-to-liquid ratio is a fraction of percent, showing the efficiency of the RBR technique for convectional mass-transfer and global mixing. The RBR was spun at 340 rpm while the transmittance at 663 nm was monitored for ca 4 h at which point the transmittance had recovered the baseline value for colorless de-ionized water.   Keywords: Ion exchange, Cleantech, Nuclear, Scale-up  

Mass transfer revolutionized

Learn how SpinChem rotating bed reactors (RBR) can eliminate poor mass transfer in heterogeneous reactions during chemical synthesis and biotransformations. Preserve activity and facilitate recycling of solid phases with the RBR. This brochure shows technology and applications.  Keywords: Biotransformation, Brochure, Fast reaction, Immobilized enzymes, Molecular sieve, Preserved activity, Simple cleanup, Synthesis, Technology

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 9001
Recycling of Immobilized Enzymes – Simple and Streamlined Biocatalysis

Immobilized catalyst recycling using a SpinChem® rotating bed reactor (RBR) and a Mettler-Toledo EasyMax™ 102 Advanced synthesis workstation. The process proved very time efficient as no filtration steps were needed between cycles, or for the samples extracted for analysis during each run. Washing of the resin between runs was fast, simple and robust, without running the risk of material loss. Keywords: Biotransformation, Immobilized enzymes, Mettler-Toledo, Organic molecules, Preserved activity, Quick recycling

Application 1039
Remediation of wastewater stored in High Integrity Container

The versatility of the ProRBR IBC add-on (picture below) was demonstrated by mounting it on a high-integrity container (HIC) (picture above) and running a sample reaction. The ProRBR IBC add-on can be placed on most reasonably stable supports. In this case, the RBR add-on was placed over the HIC opening by support of a common construction scaffold. A common ion-exchange reaction, de-ionization by 7 L of mixed-bed resin to 3000 L of municipal water, was carried out to measure the performance. The ion concentration/ conductivity was halved after ca 30 min and after 2 h it was down to our LOQ.

Application 1032
Rotating bed reactor for immobilized enzymatic reactions

Poster on a case study of applying the rotating bed reactor for the lipase-mediated stereoselective acetylation of a racemate amine as a model reaction for the manufacturing of pharmaceutical building blocks. The results showed that enzyme recycling and synthesis scale up was easy to achieve with preserved yield, enantioselectivity and catalytic activity.   Keywords: Biotransformation, Easy handling, Immobilized enzymes, Quick recycling, Seamless scaleup

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 1036
Screening of activated carbon using the SpinChem® RBR S2

In co-operation with ZHAW, two students screened various types and sizes of activated carbon using the SpinChem® RBR S2. Five different carbons were screened by decolorizing solutions of methylene blue in distilled water. The decolorization process was monitored using inline UV-Vis spectrometry (PAT). The results show the importance of choosing the correct media for your application. In this case of activated carbon, the source and type of the activation was shown to have a major impact on performance.  Keywords: Activated carbon, Decolouration, Fast reaction, Rapid screening, Technology

Application 9002
Screening of Immobilized Enzymes – Fast and Convenient Reaction Optimization

The stable reaction environment in the EasyMax™ 102 Advanced synthesis workstation and the high flow rates through the SpinChem® RBR allowed for quick and convenient screening of different immobilized lipases to find the enzyme most suitable for further reaction optimization.   Keywords: Biotransformation, Immobilized enzymes, Mettler-Toledo, Organic molecules, Rapid screening

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. Many heterogeneous processes (e.g. adsorption or catalysis) are made faster by increasing the solid-to-liquid ratio. Studying scale-up effects can also help to predict full-scale performance. For these reasons it’s wise to invest in equipment that can handle different operating conditions such as liquid volume, solids loading, pH and temperature. The RBR S3 Plus is the most modular rotating bed reactor for laboratory use. Made from two stacked rotating bed reactors, the S3 Plus quickly converts to a single RBR S3 for use with smaller liquid volumes. When used in the dedicated glass reactor system, this yields an operating range of 250 - 1500 mL of liquid and 0 - 140 mL of solids.   This application note investigates the effect of solids loading on the reaction rate of two applications: the adsorption of a dye and a biocatalytic esterification reaction. These two reactions are mass-transport limited and relatively fast. In the first case, an RBR S3 and an RBR S3 Plus were filled with 50 mL and 100 mL respectively of the ion-exchange resin Purolite® NRW1160. Methylene blue was dissolved in water, and the solution was decolorized by spinning an RBR at 600 RPM (reaction conditions in the details below). The results were clear; each case followed 1st order kinetics with a rate constant for the RBR S3 Plus that was twice that of the RBR S3. Note that the solid-to-liquid ratio for the RBR S3 Plus was also twice that of the RBR S3. For the enzymatic esterification, the same rotating bed reactors (RBR S3 and RBR S3 Plus) were filled with 40 mL and 80 mL respectively of the biocatalyst Purolite® immo PS. The rotating bed reactors were used in separate reactions in mixtures of lauric acid, 1-propanol and water. Also in this case the reaction rate was proportional to the solid-to-liquid ratio, yielding twice the productivity with the RBR S3 Plus compared to the RBR S3. The conclusion is that with a rotating bed reactor you are making the most out of the solid-phase. Doubling the amount of catalyst or adsorbent will generally double the reaction rate constant, which makes scaling up straightforward. Contact us today to discuss how we can scale your process.

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, often involve multiple steps using heterogeneous catalysts or adsorbents. The need often arises for simultaneous use of multiple solid phases.

Application 9003
Simultaneous Selective Decolouration – Illustrating a Concept for Cascade Reactions

Two dyes were selectively extracted onto different adsorbents within the same run using a SpinChem® rotating bed reactor (RBR) and an EasyMax™ 102 Advanced synthesis workstation. This experiment illustrates performing cascade reaction for one-pot multi-step synthesis.  Keywords: Cleantech, Decolouration, Extraction, Ion exchange, One-pot multistep, Organic molecules, Polymeric resin, Technology

Application 1040
The importance of baffles in a reactor vessels

baffle (noun) : a device (such as a plate, wall, or screen) to deflect, check, or regulate flow or passage (as of a fluid, light, or sound) Can you use a rotating bed reactor (RBR) in any type of vessel? Absolutely. Would the performance be higher with baffles in the vessel? Definitively. A vortex, which forms due to the rotation of an agitator, is detrimental to the mixing in a reactor vessel. If the agitator is a rotating bed reactor, it also disrupts the flow through the RBR. Baffles are features in the reactor vessel that break the circulating flow pattern, preventing vortex formation and improving overall mixing. The importance of baffles has long been established for stirred tank reactors with agitation by impellers, and baffling is equally important for vessels with an RBR installed. You don't need to take our word for it; customers that have investigated the effect of baffling on their mass-transfer limited reactions have found the same result. The most recent data comes from research at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB. They started out with the RBR S3 in a smooth glass vessel. After observing a deep vortex, drawn down into the RBR, and the resulting disappointing performance, one simple flat-blade baffle was installed. The performance for the enzymatic reaction was quantified with and without the flat-blade baffle, and the result is presented in the figure below. As seen in the data, installing one simple baffle resulted in a doubled yield at each time point on average. The double-walled glass vessels (V2 and V3) that SpinChem offer are custom-made to fit the RBR S2 and S3 respectively. The vessels have structured inner glass walls that serve as "flower-shaped" baffles, which do not take up the same space as traditional flat-blade baffles. This minimizes the required volume of reaction medium, and maximizes mixing performance.   Some non-baffled vessels perform as if they had flow breakers installed, just through the shape of their vessel walls. For instance, any non-round geometry such as rectangular IBC-tanks may provide satisfactory mixing and prevention of a deep vortex forming. On benchtop scale, the round beaker is appealing with its simplicity, but a baffled reaction vessel will yield much better performance. If you have more questions about this contact us.

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.

Treatment of 7.5 m3 with a 50L 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 existing 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 9004
Treatment of Viscous Solutions – Simple Extraction and In-line Monitoring

Blue dye was removed from a highly viscous liquid using a SpinChem® RBR S2 in an EasyMax™ 102 Advanced Synthesis Workstation. Monitoring of the reaction was easily recorded as no freely suspended ion exchange resin beads or resin debris interfered with the readings. This demonstrates that the RBR technology is extremely well suited for in-line monitoring. The viscosity of the solution was determined to ca 230 cP at 25°C, showing that it is possible to absorb dye even from a highly viscous solution.  Keywords: Decolouration, Extraction, Ion exchange, Mettler-Toledo, Viscous solutions

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, 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 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.

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