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A novel reactor for heterogeneous catalysis
Andrea Adamo and Lorenzo Milani of Zaiput Flow Technologies share a new approach for carrying out hydrogenations safely and continuously
Hydrogenation is a key transformation in organic synthesis, widely used across the chemical and pharmaceutical industries. However, it presents inherent safety risks due to the flammability of hydrogen gas.
Operating under pressure can enhance reaction efficiency but also increases safety concerns and the cost of the engineering controls required to mitigate these risks. Additionally, the use of precious metal-based heterogeneous catalysts contributes significantly to overall process costs, particularly when catalyst utilisation is inefficient.
To address these challenges, continuous hydrogenation is being actively explored as a safer and more cost-effective alternative to traditional batch processes. This approach offers potential advantages, including improved process control, enhanced catalyst efficiency and overall operational safety.
Packed-bed reactors( PBRs) are the standard technology for implementing hydrogenation in flow. However, the most effective catalysts are often fine powders with median particle sizes between 10 and 30 µ m, which leads to high pressure drops and limits scalability.
To accommodate larger-scale operations, trickle-bed reactors( TBRs) using larger catalyst pellets are typically employed. While these reduce pressure drop, they compromise catalytic activity because of their lower surface area.
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Modular layered design Same concept across scales
a
b
Modular layered design
Modules can be stacked as needed to target any chemistry
Gas inlet piece
◄------( Gas is uniformly distributed and mixed with the liquid in the entire reactor cross section)
Packed bed lir
• Heat removed radially t
Flowrate = Q Height = H Area = A Volume = A * H Velocity = Q / A
i'.iP p sR o(
Outlet
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tttttttttttttttttttt tttttttttttttttttttt
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Coolant IN Liquid IN Coolant OUT
H, Q / A
• Long heat transfer length scale( bed radius)
• Possible Hot spots
• High i'.iP due to high velocity and height
Figure 1- Cross-section( a) & picture( b) of Tower Reactor
Despite some progress and a growing number of commercial-scale applications, the industry has yet to adopt a standardised, scalable reactor design that fully capitalises on the benefits of continuous hydrogenation. As a result, most hydrogenation processes remain in batch mode, limiting the potential gains in efficiency, safety and cost reduction.
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• GaslN
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Zaiput tower reactor hl
• Heat removal axially
Outlet piece( Process fluids are collected and exit together)
Catalyst module
Catalyst module
Heat exchanger module
Catalyst module( Catalyst is optimally packaged)
Heat exchanger module( for temperature control of the process stream)
Liquid inlet piece( Liquid is uniformly distributed in the entire reactor cross section)
Scaling = X( X >> 1) Flowrate = Q Height = H / X Area = A * X Volume = A * H Velocity = Q / A / X
i'.iPPBR o( HIX, Q /( A * X)
• Short heat transfer length scale( as low as½ of cat. cartridge)
• No hot spots
• Low i'.iP due to lower velocity and height
There is a clear and pressing need for a continuous reactor system that can effectively utilise fine powdered catalysts, combining high catalytic performance with scalable, industrially viable reactor configurations.
Reactor concept
Traditional PBR designs typically rely on tall, narrow geometries. This configuration is intended to promote
50 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981