Continuous flow tubular reactor

Recipe ingredients can also be added at intermediate points along the reactor train. Continuous-flow tubular reactors can be used in series with the tanks, usually as a prereactor in front of the tanks. 

Continuous flow tubular reactor o Continuous flow tubular reactor... 

The cracking of diphenylmethane (DPM) was carried out in a continuous-flow tubular reactor. The liquid feed contained 29.5 wt.% of DPM (Fluka, >99%), 70% of n-dodecane (Aldrich, >99% solvent) and 0.5% of benzothiophene (Aldrich, 95% source of H2S, to keep the catalyst sulfided during the reaction). The temperature was 673 K and the total pressure 50 bar. The liquid feed flow rate was 16.5 ml.h and the H2 flow rate 24 l.h (STP). The catalytic bed consisted of 1.0 g of catalyst diluted with enough carborundum (Prolabo, 0.34 mm) to reach a final volume of 4 cm. The effluent of the reactor was condensed at high pressure. Liquid samples were taken at regular intervals and analyzed by gas chromatography, using an Intersmat IGC 120 FL, equipped with a flame ionization detector and a capillary column (Alltech CP-Sil-SCB). 

Ortho-xylene (A) is oxidised to phthalic anhydride (B) in an ideal, continuous flow tubular reactor. The reaction proceeds via the complex consecutive parallel reaction sequence, shown below. The aim of the reaction is to produce the maximum yield of phthalic anhydride and the minimum production of waste gaseous products (C), which are CO2 and CO. 

Ethyl formate is to be produced from ethanol and formic acid in a continuous flow tubular reactor operated at a constant temperature of 303 K (30°C). The reactants will be fed to the reactor in the proportions 1 mole HCOOH 5 moles C2H5OH at a combined flowrate of 0.0002 m3/s (0.72 m3/h). The reaction will be catalysed by a small amount of sulphuric acid. At the temperature, mole ratio, and catalyst concentration to be used, the rate equation determined from small-scale batch experiments has been found to be ... 

While alkane metathesis is noteworthy, it affords lower homologues and especially methane, which cannot be used easily as a building block for basic chemicals. The reverse reaction, however, which would incorporate methane, would be much more valuable. Nonetheless, the free energy of this reaction is positive, and it is 8.2 kj/mol at 150 °C, which corresponds to an equiUbrium conversion of 13%. On the other hand, thermodynamic calculation predicts that the conversion can be increased to 98% for a methane/propane ratio of 1250. The temperature and the contact time are also important parameters (kinetic), and optimal experimental conditions for a reaction carried in a continuous flow tubular reactor are as follows 300 mg of [(= SiO)2Ta - H], 1250/1 methane/propane mixture. Flow =1.5 mL/min, P = 50 bars and T = 250 °C [105]. After 1000 min, the steady state is reached, and 1.88 moles of ethane are produced per mole of propane consumed, which corresponds to a selectivity of 96% selectivity in the cross-metathesis reaction (Fig. 4). The overall reaction provides a route to the direct transformation of methane into more valuable hydrocarbon materials. 

Aimular shape. Continuous flow, tubular reactor in two sections of one meter each 13,000 cm ... 

The polymerization time in continuous processes depends on the time the reactants spend in the reactor. The contents of a batch reactor will all have the same residence time, since they are introduced and removed from the vessel at the same times. The continuous flow tubular reactor has the next narrowest residence time distribution, if flow in the reactor is truly plug-like (i.e., not laminar). These two reactors are best adapted for achieving high conversions, while a CSTR cannot provide high conversion, by definition of its operation. The residence time distribution of the CSTR contents is broader than those of the former types. A cascade of CSTR s will approach the behavior of a plug flow continuous reactor. 

Example 6-2 Experimental response measurements on a continuous-flow tubular reactor give the following RTD ... 

Reactor The experiments were performed in a continuous flow tubular reactor (Pyrex, 8 mm OD, 5 mm ID). The catalyst sample was held by a plug of quartz wool on top of a thermocouple. All gases and gas mixtures were of high purity grade and not further purified. Calibrated mass flow controllers assured e desired concentrations. 

For heat transfer applications the static mixer has an advantage over the empty tube in that it has a much more uniform residence time distribution characteristic, further reducing the possibility of damage to heat sensitive materials. The more uniform residence time characteristic has other advantages, particularly for the design of continuous flow tubular reactors. 

Several designs are shown in Figure 22.12 (a) common batch cleaning bath reactor with wall mounted transducers (b) batch reactor with immersible transducers (c) batch reactor with sonic probe (d) continuous flow tubular reactor with wall-mounted transducers (e) the Harwell sonochemical reactor and (f) a shell-and-tube reactor. A number of other designs are discussed by Thompson and Doraiswamy (1999b). 

ILLUSTRATIVE EXAMPLE 21.19 The concentration, C, variation with length, z, in a 3 ft continuous flow tubular reactor (TF) is described by the equation ... 

Two independent studies compared RAFT polymerization (of MM A, BA, VAc, NIP AM or DMAM) in conventionally-heated continuous-flow tubular reactors with those in a microwave-heated batch reactor. A rapid rate of polymerization was observed for both systems. There were no significant differences in the polymerization kinetics or in the molecular weight or dispersity of the polymer produced. These results suggest that there is no microwave effect beyond that of rapid heating of the reaction medium. 

Fig. 6.17 Continuous-flow tubular reactors developed by (A) Jang et al (2004), and (B) Moon et al (2005) for electricity generation. The flow moves from the anode chamber into the cathode chamber where it is sparged with air. (Reprinted with permission from Elsevier.)...

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