Gradientless internal recycle reactor

Bertucco, A., Canu, P., Devetta, L. Catalytic Hydrogenation in Supercritical C02 Kinetic Measurements in a Gradientless Internal-Recycle Reactor. Ind. Eng. Chem. Res. 1997, 36, 2626 - 2633. 

A Bertucco, P Canu, L Devetta, AG Zwahlen. Catalytic hydrogenation in supercritical CO2 kinetic measurements in a gradientless internal-recycle reactor. Ind Eng Chem Res 36 2626-2633, 1997. 

Jankowski et al (1978) discuss in detail the great variety of gradientless reactors proposed by several authors with a pictorial overview in their paper. All of these reactors can be placed in a few general categories (1) moving catalyst basket reactors, (2) external recycle reactors, and (3) internal recycle reactors. 

As in any heterogeneous catalytic reaction (Chapter 7), it is necessary to use a gradientless reactor to obtain precise kinetic data. An internal recycle reactor was recently proposed by Bertucco et al. (1997) for this purpose. The data should be obtained at times shorter than needed for a perceptible onset of deactivation. 

Gradientless operation both with respect to temperature and concentration can be obtained by an external or internal recycle (Figure 4.11.10). In a recycle reactor the gas passes several times through the catalyst bed until the product gas leaves the reaction volume. This type of reactor is more elaborate in design, but evaluation is simpler as the rate can be determined directly. As there is a very high flow rate in... 

Different laboratory reactors are used for kinetic studies. For studies of liquid-liquid reactions and homogeneously catalyzed reactions, a batchwise operated stirred tank reactor is frequently used. Tubular reactors loaded with catalyst (fixed bed) are more common for studies of heterogeneously catalyzed gas reactions. The tubular reactor displays a simple design and is easy to operate. A simultaneous integral and differential mode of operation can be achieved by a tap reactor for measuring concentration and temperatures at defined axial positions. Gradientless operation with respect to temperature and concentration can be obtained by an external or internal recycle. 

The most appropriate laboratory reactor for detailed kinetic investigations is the continuously operated, gradientless recycle reactor. A large number of different constructions is described in the literature /44/. We have developed and successfully used for many years for heterogeneously catalysed vapor phase reactions such a reactor with internal recirculation (Fig. 21) It can be operated up to 800 K and 50 bars (catalyst volume 10 cm ). 

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