Microreactor geometry

Ni, Z. Seebauer, E.G. Masel, R.I. Effects of microreactor geometry on performance differences between posted reactors and channel reactors. Ind. Eng. Chem. Res. 2005, 44, 4267-4271. 

S. Belochapkine, J. Shaw, D. Wenn, J.R.H. Ross, The synthesis by deposition-precipitation of porous gamma-alumina catalyst supports on glass substrates compatible with microreactor geometries, Catal. Today 110 (2005) 53. 

Figure 2.8. The microreactor geometries most frequently used in FIA A, straight open tube B, coiled tube C, mixing chamber D, single-bead string reactor (SBSR) and E, knitted reactor. (For an example of the imprinted meandering reactor, see Chapters 3 and 4.)...

The segmented flow condition may be created by several contrasting microreactor geometry configurations, including (i) simple T-junction, (ii) constriction junction, (iii) sheath flow junction, and (iv) fluidic oscillator arrangements [155]. The precision of fluid volume elution controlled by these means depends on several factors. 

Microreactor scale-up is built upon the premise of numbering up channels. Figure 11.1. A single channel is demonstrated with the same geometry and fluid hydrodynamics as a full-scale reactor. Numbering up rehes on creating a massively... 

The up-scaling from microreactor to small monoliths principally deals with the change of geometry (from powdered to honeycomb catalyst) and fluid dynamics (from turbulent flow in packed-bed to laminar flow in monolith channels). In this respect, it involves therefore moving closer to the conditions prevailing in the real full-scale monolithic converter, while still operating, however, under well controlled laboratory conditions, involving, e.g. the use of synthetic gas mixtures. 

The efforts and advances during the last 15 years in zeolite membrane and coating research have made it possible to synthesize many zeolitic and related-type materials on a wide variety of supports of different composition, geometry, and structure and also to predict their transport properties. Additionally, the widely exploited adsorption and catalytic properties of zeolites have undoubtedly opened up their scope of application beyond traditional separation and pervaporation processes. As a matter-of-fact, zeolite membranes have already been used in the field of membrane reactors (chemical specialties and commodities) and microchemical systems (microreactors, microseparators, and microsensors). 

Additionally, in a microreactor the intrinsic kinetics and deactivation behavior of SCR catalysts is studied with flows up to 1.5m h . In both test facilities it is possible to vary all process parameters temperature, the ammonia to nitric oxide feed ratio, the nitric oxide and sulfur dioxide concentrations, the space velocity, and the catalyst geometry. These techniques provide information for somewhat small areas and therefore should always be performed to complement bench- or laboratory-scale activity and selectivity measurements. 

Microreactors consist of well-defined geometries, but multi-layered structures when compared to larger-scale conventional reactors... 

The microreactor between the injection port and the detector may have different length, diameter, and geometry. 

The coiled tube has so far been the most frequent geometric form of the FIA microreactor. However, it is useful to review all channel geometries (Fig. 2.8). These are straight tube (A), coiled tube (5), mixing chamber (C), single-bead string reactor (D), 3-D or knitted reactor (E)y and imprinted meander (cf. microconduits Section 4.12) or combinations of these geometries. 

Figure 2.10. Dispersion of a dye, injected as a sample zone (Sy = 25 jiL) into A, straight tube By coiled tube C, knitted tube and D, a SBSR reactor. The reactor volumes (Vr = 160 iL) and pumping rates (Q = 0.75 mL/min) were identical in all experiments. The same piece of Microline tubing (L = 80 cm, 0.5 mm inside diameter) was used in experiments Ay By and C. (The injected dye was bromthymol blue, carrier stream 0.1 M borax and wavelength 620 nm, cf. Chapter 6.) The SBSR reactor was made of 0.86 mm inside diameter tube filled with 0.6-mm glass beads. Note that the isodispersion points on the peaks were recorded with microreactors made of identical length and diameter, but different geometry.

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