Stirred batch mode

FIGURE 8.4 Effect of solvent removal and the stepwise addition of fructose on the percent conversion of saccharide (a) and on the solubility of fructose (b) for lipase-catalyzed fructose-oleic acid esterification. ( ) Fructose was added to 50 mmol oleic acid and 13.4 g tert-butanol in 5 mmol increments for 2-h cycles until the net amount of fructose added was 25 mmol tert-butanol underwent free evaporation for up to 10 h, at which time, the reaction was stopped, solvent was removed completely by rotary evaporation, then the reaction was continued. (A) Fructose (25 mmol) was added at time 0 to 50 mmol of oleic acid and 13.4 g (46.9 wt.% fructose-free basis) tert-butanol solvent freely evaporated away throughout at a rate of 0.47 g per h. Both reactions were operated in stirred batch mode using approximately 0.5 g immobilized C. antarctica lipase, (Chirazyme L-2, s.-f, c2, Lyo., Boehringer-Mannheim, Indianapolis, IN), a stir rate of 450 rev min and a reaction temperature of 65°C. (From Walde, P. et al., Chem. Phys. Lipids, 53, 265-288, 1990. With permission.)... 

Chapter 2 treated multiple and complex reactions in an ideal batch reactor. The reactor was ideal in the sense that mixing was assumed to be instantaneous and complete throughout the vessel. Real batch reactors will approximate ideal behavior when the characteristic time for mixing is short compared with the reaction half-life. Industrial batch reactors have inlet and outlet ports and an agitation system. The same hardware can be converted to continuous operation. To do this, just feed and discharge continuously. If the reactor is well mixed in the batch mode, it is likely to remain so in the continuous mode, as least for the same reaction. The assumption of instantaneous and perfect mixing remains a reasonable approximation, but the batch reactor has become a continuous-flow stirred tank. 

Continuous Stirred Tanks Without Biomass Recycle. The chemostat without biomass recycle is a classic CSTR. The reactor is started in the batch mode. 

Therefore, many traditional designs, such as stirred tank reactors, incorporate heat transfer in the process (jacket, external or internal coil, etc.). However, in these devices, there is a significant distance between the heat transfer site and the site of the chemical reaction where heat is released. As a consequence semibatch mode is implemented while batch mode and/or systems are diluted. 

Crameri et al. (1997) have reported an asymmetric hydrogenation constituting an important step in the production of a new calcium antagonist, Mibefradil (POSICOR) (of Hoffmann-LaRoche). Pilot-scale synthesis of (S)-2-(4-flurophenyl)-3-methylbutanoic acid by the asymmetric hydrogenation of 2-(4-fluorophenyl)-3-methyl but-2-enoic acid with a [Ru (/ )-MeOBIPHEP)(OAc)2]-catalyst has been described. The hydrogenation was performed in a continuous mode in a cascade stirred-tank reactor system at a pressure of 270 bar. A large reduction in total reactor volume compared to the batch mode was realized. 

Stirred-tank reactors can be operated in batch, semi-batch, or continuous mode. In batch or semi-batch mode ... 

Esterification of stearic acid and acetic acid with propanol and butanol in the presence of Fe2(S04)3/KSF montmorillonite [37]. The rate enhancement observed (1.5-2.5 times) was ascribed to the higher temperature of the catalyst bed (calculated to be 9-18 K above the bulk temperature). Reaction conditions batch (no stirring) and a stirred single-mode tank reactor, catalyst particle size 5 mm, 10-fold excess of alcohol. 

This section presents the result of the catalytic performances in the case of phenylacetylene hydrogenation reaction. The catalytic evaluation was performed in a classical well-stirred stainless steel reactor operating in batch mode under constant H2 pressure (10 bar) at 17°C using n-heptane as the solvent. As mentioned in Section 13.2.2, no modification of the particle size distribution has been observed by transmission electron microscopy before or after reduction of colloidal oxide particles. 

Reactions were carried out in liquid phase in a well-stirred (1000 rpm) high-pressure reactor (Parr Instruments, 300 mL) at 30 bar and 150°C. The reaction mixture consisted of 61 g of ADPA (Acros Chemicals), 53 g MIBK (Acros Chemicals) and 370 mg of catalyst. The test procedures used here is similar to that described earlier by Bartels et al. (7). The reactor was operated at a constant pressure with the liquid phase in batch mode and the hydrogen fed in at a rate proportional to its consumption. The reaction was monitored by hydrogen uptake and the product yield was determined from gas chromatographic (Agilent Technologies, 6890N) analysis. 

So far, all the studies discussed have involved Deloxan used in the fixed bed mode. Its use in batch mode was also investigated. When 9 g wet Deloxan was added to a beaker containing 100 mL of 20 ppm Cl2Ru(PPh)3 in either toluene or DMF at 50 °C and stirred with an overhead stirrer for 3 h, the concentration of Ru in the filtrate was... 

In most arrangements used for AAS, the batch mode of operation is preferred (Fig. 7.2a). The acidified s. is transported into a stirred glass cell containing 1% w/v aqueous sodium borohydride. The contents are i and the liberated hydrides flushed with an inert gas into either... 

Biochemical reactors can be operated either batchwise or continuously, as noted in Section 1.5. Figure 7.1 shows, in schematic form, four modes of operation with two types of reactors for chemical and/or biochemical reactions in Uquid phases, with or without suspended solid particles, such as catalyst particles or microbial cells. The modes of operation include stirred batch stirred semi-batch continuous stirred and continuous plug flow reactors (PFRs). In the first three types, the contents of the tanks arc completely stirred and uniform in composition. 

An analysis based on reaction kinetics suggests that up to 50% of manufacturing reaction steps in the fine chemical and pharmaceutical industries could benefit from being run continuously rather than in batch mode in a stirred tank reactor... 

Figure 1-2 Operating parameters necessary for ozone mass balance(s) on a continuous-flow stirred tank reactor (for operation in semi-batch mode Ol - 0).

For example, Beltran and Alvarez (1996) successfully applied a semi-batch agitated cell for the determination of kL k,a, and the rate constants of synthetic dyes, which react very fast with molecular ozone (direct reaction, kD = 5 105 to 1 108 L mol-1 s l). In conventional stirred tank reactors operated in the semi-batch mode the mass transfer coefficient for ozone kLa(03) was determined from an instantaneous reaction of ozone and 4-nitrophenol (Beltran et al., 1992 a) as well as ozone and resorchinol (l,3-c//hydroxybenzene) or phloroglucinol... 

If we compare the sparged (BSCR) and mechanically stirred (MSSR) reactors, we can stress that the slurry bubble column may be operated in a semi-batch mode, does not use any moving parts, and requires minimal maintenance, smaller floor space and has lower power consumption. 

Experiments were carried out in a 0.3 litre stirred autoclave (Autoclave Engineers type Magne-Drive) operating in a batch mode andequipped with a system for sampling of liquid during the course of the reaction... 

The reactions were carried out in a 0.1 liter stirred autoclave operating in a batch mode and equipped with a system for sampling of liquid during the reaction. The autoclave was charged with the substrate together with solvent and the freshly calcinated zeolite (calcination overnight at 500°C or 400°C in air, prior to use) and then heated to the desired temperature. The amounts of zeolite and of distilled water depend both on the nature and the concentration of substrate. Samples were withdrawn periodically and analyzed by g.l.c..Two typical examples are described below ... 

A condensation reaction is to be in a stirred tank reactor in the semi-batch mode. The solvent is acetone, the industrial charge (final reaction mass) is 2500 kg, and... 

A reaction A——>P is to be performed in a PFR. The reaction follows first-order kinetics, and at 50 °C in the batch mode, the conversion reaches 99% in 60 seconds. Pure plug flow behavior is assumed. The flow velocity should be 1 m s"1 and the overall heat transfer coefficient 1000Wm 2 K"1. (Why is it higher than in stirred tank reactors ). The maximum temperature difference with the cooling system is 50 K. 

The condensation of an aromatic nitro compound with a second reactant should have been performed in an aqueous solution with DMSO in the semi-batch mode. The nitro-compound is initially charged into the reactor with water and DMSO as solvent. Before the progressive addition of the second reactant had been started, the initial mixture was heated to the process temperatures of 60-70 °C. Then a failure of the cooling water system of the plant occurred. It was decided to interrupt the process at this stage and to maintain the mixture under stirring until the failure had been repaired. The feed of the second reactant was postponed and the jacket of the reactor had been emptied. 

Plants may have large (several hundred gallon capacity) nitration vessels operating in a batch mode or small continuous units. The temperature is held at about 50°C, governed by the rate of feed of benzene. Reaction is rapid in well-stirred and continuous nitration vessels. The reaction products are... 

The slurry tank, when well mixed, can be considered a continuous-stirred tank reactor for both the gas phase and the liquid phase. When the solid is retained in the reaction vessel, it behaves in a batch mode however, catalyst can be removed and regenerated easily in a slurry tank, so activity can be maintained. 

Parameter Stirred-tank bioreactors operated in batch and fed-batch mode Stirred-tank bioreactors operated in perfusion mode Heterogeneous bioreactors (packed-bed or hollow-fiber) operated in perfusion mode... 

In the production of 2, strains with entA - mutation have long-term stability and production rates are high. Typical cultivation of 2,3-trans-CHD 2 is performed at pH 6.8 and 37 °C in a stirred-tank reactor with glucose feeding in a fed-batch mode. Microbial production over a process time of 40 h affords 92 g 2 from 690 g glucose monohydrate in a 20-L cultivation experiment. This corresponds to a molar yield of 17% [13]. Advantageously, 2,3-trans-CHD 2 is the major product with no... 

The experiments were performed in batch mode with stirring. The sensor was placed in 20.00 mL of buffer in a three electrode configuration. The potential was applied (+150 mV vs SCE) and the response was allowed to reach baseline. The required amount of analyte was added to measure the response to electroactive interferents and to generate a glucose calibration curve. 

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