Structured catalytic reactors

Fig. 6. Examples of types of meshes developed to resolve laminar flow around particles (a) Chimera grid. Reprinted, with permission, from the Annual Review of Fluid Mechanics, Volume 31 1999 by Annual Reviews www.annualreviews.org (b) Unstructured grid with layers of prismatic cells on particle surfaces. Reprinted from Chemical Engineering Science, Vol. 56, Calis et al., CFD Modeling and Experimental Validation of Pressure Drop and Flow Profile in a Novel Structured Catalytic Reactor Packing, pp. 1713-1720, Copyright (2001), with permission from Elsevier.

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

Structured reactors and catalysts are encountered in a large variety (3,6). Structured catalytic reactors can be divided into two categories. The first involves a structured catalyst, whereas the second one involves normal catalyst particles arranged in a nonrandom way. In the first category, the catalyst and the reactor are essentially identical entities. 

Because of their low pressure drop, structured reactors in practice dominate the field for treating tail gases. Figure 2 presents the major types of reactor. The monolithic reactor represents the class of real structured catalytic reactors, whereas the parallel-passage reactor and the lateral-flow reactor are based on a structured arrangement of packings with normal catalyst particles. 

It is fair to state that by and large the most important application of structured reactors is in environmental catalysis. The major applications are in automotive emission reduction. For diesel exhaust gases a complication is that it is overall oxidizing and contains soot. The three-way catalyst does not work under the conditions of the diesel exhaust gas. The cleaning of exhaust gas from stationary sources is also done in structured catalytic reactors. Important areas are reduction of NOv from power plants and the oxidation of volatile organic compounds (VOCs). Structured reactors also suggest themselves in synthesis gas production, for instance, in catalytic partial oxidation (CPO) of methane. 

To reduce the decomposition, H202 is evaporated in a micro structured falling film evaporator at the bottom of the plant The gaseous H202 flows upwards to the micro structured mixer where it is mixed with propylene. This mixture is guided through the likewise micro structured catalytic reactor. The mixture of the reaction, mainly propylene oxide, unreacted propylene and water is carried off at the top of the plant [100],... 

Reactive Stripping in Structured Catalytic Reactors Hydrodynamics and Reaction Performance... 

Microreactors belong to the family of sfructured reactors as well (Figure 6). Current microfabrication techniques allow fabrication of small structured catalytic reactors (8). The versatile fabrication possibilities for chip-based reactors have led to the simultaneous development of sfructured and unstructured reactors (9,10), but in the final analysis, the structured version was usually favored. 

L. Kiwi-Minsker, Novel structured materials for structured catalytic reactors, Chimia 56 (2002) 143. 

M. Roumanie, V. Meille, C. Pijolat, G. Tournier, C. De Bellefon, P. Pouteau, C. Delattre, Design and fabrication of a structured catalytic reactor at micrometer scale Example of methylcyclohexane dehydrogenation, Catal. Today 110 (2005) 164. 

T. Giornelli, A. Lofberg, E. Bordes-Richard, Preparation and characterization of VOx/ Ti02 catalytic coatings on stainless steel plates for structured catalytic reactors, Appl. Catal. A-Gen. 305 (2006) 197. 

Renken, A. and Kiwi-Minsker, L. (2010) Micro-structured catalytic reactors. Adv. 53 Catal., 53, 47-122. 

G. Kolb, V. Hessel, V. Cominos, et ol. Selective oxidations in micro-structured catalytic reactors—For gas-phase reactions and specifically for fuel processing for fuel cells. Catal. Today 2007, 120, 2-20. 

Roumanie, M., Meille, V., Pijolat, C., Tournier, G., de Bellefont, C., Pouteau, P. and Delattre, C. (2005) Design and fabrication of a structured catalytic reactor at micrometer scale example of... 

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