Catalytic reactors wire gauzes

FIGURE 11.31 A typical catalytic wire-gauze reactor. 

In addition to the two most common reactors described above, other designs have also been used. The most important of these reactors are the radial-flow and catalytic wire-gauze reactors, followed by the rather infrequently used spherical reactor. 

Figure 8.12 A typical catalytic wire-gauze reactor. (Adapted from Joshi, J.B. and Doraiswamy, L.K. Chemical Reaction Engineering, in Albright s Chemical Engineering Handbook, CRC Press, Albright, Boca Raton, FL, 2009.)...

Wire Gauzes Wire screens are used for very fast catalytic reactions or reactions that require a bulk noble metal surface for reaction and must be quenched rapidly. The nature and morphology of the gauze or the finely divided catalyst are important in reactor design. Reaction temperatures are typically high, and the residence times are on the order of milliseconds. 

Not all catalysts need the extended smface provided by a porous structure, however. Some are sufficiently active so that the effort required to create a porous catalyst would be wasted. For such situations one type of catalyst is the monolithic catalyst. Monolithic catalysts are normally encountered in processes where pressure drop and heat removal are major considerations. Typical examples include the platinum gauze reactor used in the ammonia oxidation portion of nitric acid manufacture and catalytic converters used to oxidize pollutants in automobile exhaust. They can be porous (honeycomb) or non-porous (wire gauze). A photograph of a automotive catalytic converter is shown in Figure CD 11-2. Platinum is a primary catalytic material in the monolith. 

In this section we develop the design equations and give the mass transfer correlations for two common types of catalytic reactors the wire screen or catalyst gauze reactor and the monolith reactor. 

Critical effects in CO oxidation over Pt catalysts were obtained [33, 34, 63-85] in various catalytic systems over wires, foils and gauzes, on single pellets and fixed beds, in isothermal and adiabatic reactors (differential and integral). The literature also reported the oscillating behaviour of the homogeneous oxidation of CO [86, 87]. 

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