Channel Reactor

Reactor channel upper width, lower width depth length 600 pm 515 pm 60 pm 78 mm Thermocouple element wire diameter 100 pm... 

Reactor channel width depth length 200 pm 60 pm 95 mm Operational temperature 150 °C... 

The IR spectra are finally analyzed to determine the effluent concentration from each reactor channel. The quantification of species concentration is performed using either univariate or multivariate calibration methods. For non-overlapping peaks, like CO, C02, and N20, we can use univariate calibration. This is simply performed by baseline correction, the peak areas and/or peak heights and then converting these values... 

Collins et al. (1971) carried out an experimental program to investigate parallel-channel instability in a full-scale simulated nuclear reactor channel op-... 

Collins, D. B., and M. Gacesa, 1969, Hydrodynamic Instability in a Full-Scale Simulated Reactor Channel, Proc. Inst. Mech. Eng. 184. (6)... 

Matzner, B., J. E. Casterline, E. O. Moech, and G. A. Wilkhammer, Experimental Critical Heat Flux Measurement Applied to a Boiling Reactor Channel, ASME Paper 66-WA/HT-46, Winter Annual... 

Sembler, R.J., 1960, Mixing in Rectangular Nuclear Reactor Channels, WAPD-T-653, Westinghouse Bettis Atomic Power Lab, Pittsburgh, PA. (App.)... 

Figure 11. Best characteristic of wall reactor (channel size = 0.8 mm(height) 1.0 inm(width) 113.0 mm(length), channel geometry = vortex) [30].

To illustrate the functionality of the system a validation library was prepared and introduced into the reactor system. With the goal of achieving an optimal fluid distribution with a minimal pressure drop over the 96 reactor channels we used multichannel ceramic bodies ( miniliths ) as supports, which are impregnated with the corresponding catalyst precursor solutions in an automatic manner (for suitable technical solutions see Section 2). At each of the 96 reactor positions, a candidate material modified by impregnation is available for testing. The shadowed scheme... 

MEMS technology also allows embedding of actuators and sensors in single reactor channels. Despite problems with temperature robustness, a solution must be found to transport the signals from the micro channels to the central process control system. To avoid a confusing cable set-up ( spaghetti conditions ), it is desirable to process the sensor data on-site, for example in an A/D converter, and to feed the digital data in a common bus system [13]. 

S Bubbly droplet annular flow / 4 y > 0 S ° 0 o5° io 00 < Opoo O I gas core with droplets and liquid film with gas bubbles boiling nuclear reactor channel... 

Figure 13 Map of flow regimes for n-decane and air flow at ambient conditions. A = countercurrent annular flow B = slugging flow. The hatched area represents the range of velocities corresponding with the operation of large industrial trickle-bed reactors. Channel cross section is the same as in Fig. 12.

Figure 1.8 Microfabricated silicon packed-bed reactor for phosgene on-demand production, (a) Top-view of reactor partially loaded with 60-mm activated carbon particles - the reactor channel is 20 mm long, and the image is spliced to fit the 20 mm reaction channel by omitting the long channel midsection ...

Microchip reactors often contain a mixing part, such as a T-shaped or Y-shaped junction. A typical example is shown in Figure 7.2. A substrate solution and a reagent solution are introduced to inlets A and B, respectively, through holes in the cover plate. The inlet tubes are connected to the holes. The two solutions are combined at a Y junction and a reaction takes place in a reactor channel etched on the reactor plate. Then, a product solution comes out from outlet C on the cover plate. 

Small diameters of the reactor channels ensure short radial diffusion times, leading to narrow RTDs [15,16]. The ability to accurately and precisely control the residence time is advantageous when the desired product is an intermediate in a sequence of reactions. High selectivity can be achieved by restricting the residence time and thus minimizing conversion of the intermediates. 

Employing a stacked-plate micro reactor (channel dimensions = 100 pm, volume = 2 ml), Acke and Stevens [21] investigated the continuous flow synthesis of a series of pharmaceutically relevant chromen-l-ones via the multicomponent route illustrated in Scheme 6.4. To ensure that HCN was formed within the confines of the micro reaction channel, solutions of acetic acid (12) (2 equiv.)-2-formylbenzoic acid (13) (1 equiv.) and aniline (8) (2 equiv.(-potassium cyanide (14) (1.2 equiv.) were introduced into the reactor from separate inlets. A maximum concentration of0.15 M was selected for 13 as this prevented precipitation of the reaction products and intermediates within the micro reactor. Employing a reactant residence time of 40 min, the authors obtained 3-diamino-lff-isochromen-l-one (15) in 66% yield ... 

Employing a silicon micro reactor [channel dimensions = 500 or 1000 pm (width) x 250 pm (depth)], wall-coated with the acidic zeolite titanium silicate-1 (TS-1, Si Ti ratio = 17) (83) (3 pm), Gavrilidis and co-workers [52] demonstrated a facile method for the epoxidation of 1-pentene (84) (Scheme 6.23). Using H202 (85) (0.18 M, 30wt%) as the oxidant and 84 (0.90 M) in MeOH, the effect of reactant residence time on the formation of epoxypentane (86) was evaluated at room temperature. The authors observed increased productivity within the 500 pm reaction channel compared with the 1000 pm channel, a feature that is attributed to an increase in the surface-to-volume ratio and thus a higher effective catalyst loading. 

In addition to the preparation of packed beds and monoliths, wall coating is an alternative method forthe introductionofcatalysts into continuous flow systems, due to the short diffusion distances obtained within micro reaction channels. An early example of this was demonstrated by Yeung and co-workers [59]. who employed a stainless-steel micro reactor [channel dimensions = 300 pm (width) x 600 pm (depth) x 2.5 cm (length)] coated with an NaA zeolite membrane, followed by a layer of... 

In a second example, Ryu and co-workers [87, 88] demonstrated the nitrite photolysis (Barton reaction) of the steroidal substrate 157 to afford 158 (Scheme 6.41), a key intermediate in the synthesis of an endothelin receptor antagonist, using a 300 W high-pressure mercury lamp. Maintaining a gap of 7.5 cm between the stainless-steel/glass reactor [channel dimensions = 1000 pm (width) x 107 pm (depth) x 2.2 m (length)] and the light source, an acetone solution of the nitrite... 

Reaction testing was initiated by enabling the microreactor heaters and setting the heaters either in manual or automatic control mode. In the manual control mode, the operator set the microreactor heater voltages. While in the automatic control mode, the operator could set the desired microreactor heater temperature. The product gas compositions were determined from each of the four reactor channels. 

To quantify the effect of the incomplete mixing on reaction rates in the front of the reactor channel, this same simulation was repeated assuming second order kinetics (first order in each of the two components) and Cjj = C2j = 100 mol m. A rate constant of 1.0 X 10 m moh s was used to give an intermediate level of conversion (near 25%). This case can be compared with a simulation in which the inlet boimdary conditions were changed to assume complete mixing (50 mol m of each component across the entire inlet cross section). The axial fractional conversion profiles for these two cases (unmixed and premixed feeds) are shown in Fig. 13.4, where the unmixed feed curve is the average of the calculated values for the two components. The computed conversions for the two components were... 

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