Catalytic annular reactor

Beretta, A., Baiardi, P., Prina, D., and Forzatti, P. (1999) Analysis of a catalytic annular reactor for very short contact times. Chem. Eng. Scu, 54 (6), 765-773. 

Figure 12.10 Examples of structured catalytic reactors for kinetic measurements (a) annular reactor [47, 61] (b) plate cell reactor [75].

Some other unceitainties associated with packed-bed catalytic membrane reactors arc the following. The reaction rate in the membrane layer is not easy to assess and it is likely to be different from that in the catalyst bed. The extremely small thickness of the membrane layer compared to the dimensions in the tubular and the annular regions makes the direct determination of the membrane-related parameters difficult, if not impossible in some cases. Furthermore, obtaining accurate data of the effective diffusivity for the membrane, particularly in the presence of a support layer, is not straightforward and often involves a high degree of uncertainty. 

Slug and annular patterns, bubbly flows and foams Segmented (Taylor) flow reactor In the simplest form, the gas and liquid phases are [38-41] merged into each other in a single channel. Although a variety of flow patterns can be generated, the segmented or Taylor bubble pattern is mostly preferred. These reactors have many similarities with the catalytic monolith reactors ... 

The suitability of the structured annular reactor for very fast catalytic combustion reactions was confirmed, since it allowed measurement of kinetic data under conditions closer to the ones in the commercial applications (at higher GHSV and temperature). Extrapolation from lab-scale results can therefore be avoided, as changes in the reaction mechanism may occur... 

Donazzi, A., Beretta, A., Groppi, G., and Forzatti, P. (2008) Catalytic partial oxidation of methane over a 4% Rh/ a-Al20s catalyst Part 1. Kinetic study in annular reactor. /. Catal., 255 (2),... 

A small modification of the above design, in which the catalyst in the form of granules or pellets is placed in an annular basket made of wire mesh fitted close to the reactor wall, has also been examined. The use of such an annular basket-type reactor has been reported by Tajbl et al. (1967), Relyea and Perlmutter (1968), and Lakshmanan and Rouleau (1970). The basic features of this reactor are the same as the ones described above. The reactor has been used to carry out high-pressure, high-temperature catalytic methanation of mixtures of carbon monoxide/hydrogen and carbon dioxide/hydrogen. 

The reactor is sketched in Figure 8 where three concentric annular spaces with the six catalytic walls are shovm. The reactor is fed through the outer annular space (maximum PCE concentration) where the radiation field has ifs minimum value. Exit of reactants and products occurs from the inner annular space. All details of the reactor assembly and operating conditions are described in Table 2. For more details the reader can resort to references (Imoberdorf ef al., 2006, 2007). 

Several reactors are presently used for studying gas-solid reactions. These reactors should, in principle, be useful for studying gas-liquid-solid catalytic reactions. The reactors are the ball-mill reactor (Fig. 5-10), a fluidized-bed reactor with an agitator (Fig. 5-11), a stirred reactor with catalyst impregnated on the reactor walls or placed in an annular basket (Fig. 5-12), a reactor with catalyst placed in a stationary cylindrical basket (Fig. 5-13), an internal recirculation reactor (Fig. 5-14), microreactors (Fig. 5-16), a single-pellet pulse reactor (Fig. 5-17), and a chromatographic-column pulse reactor (Fig. 5-18). The key features of these reactors are listed in Tables 5-3 through 5-9. The pertinent references for these reactors are listed at the end of the chapter. 

Figure S-12 Catalytic reactors.1 in) Reactor with catalyst lined or coated onto the reactor walk b reactor wilh catalyst placed in an annular basket...

In the above examples of catalytic membrane tubular reactors (CMTR), the transport equations for the catalytic membrane zone (i.e.. Equations (10-5) and (10-6)) are considered and solved. A simpler and less rigorous approach to modeling a CMTR is to neglect the membrane layer(s) and account for the catalytic reactions in the tube core or annular region. This approach was adopted by Wang and Lin [1995] in their modeling of a shell-and-tubc reactor with the membrane tube made of a dense oxide membrane (a... 

Another type of catalytic and yet non-permselective membrane reactors uses one side of the membrane as the phase boundary between gas and liquid reaction streams. An example is the reaction between a gaseous reactant (A) flowing in the tube core while a liquid containing the solution of the other reactant (B) in a suitable solvent flowing in the annular region (Figure 10.17) ... 

Example 12-3 A pilot plant for a liquid-solid catalytic reaction consists of a cylindrical bed 5 cm in radius and packed to a depth of 30 cm with 0.5-cm catalyst pellets. When the liquid feed rate is 0.2 liter/sec the conversion of reactant to desirable product is 80%. To reduce pressure drop, a radial-flow reactor (Fig. 12-5) is proposed for the commercial-scale unit. The feed will be at a rate of 5 ft /sec and will have the same composition as that used in the pilot plant. The inside radius of the annular bed is i to be 2 ft, and its length is also 2 ft. What must the outer radius of the bed be to achieve a conversion of 80% ... 

The reactor used was an annular one which consisted of two concentric tubes made of alumina. The inner diameter of the outside tube was 8mm and the outer diameter of the inner tube was 6mm. The catalytic activity of the tube surface was considered negligible because soot formed on the surface. A large section of the reactor (60cm) was placed inside of a high capacity electric furnace, the temperature of which was controlled within + 1 C. 

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