Homogeneous reactors semibatch

Figure 5.3-4. Semibatch stirred-tank reactor with alternative feed lines homogeneous reaction.

S.4. Guidelines for scale-up of semibatch reactors for fast homogeneous reactions in the absence of data on chemical kinetics and on the distribution of energy dissipation in the reaction zone... 

Figure 12.3 illustrates some modes of operation of semibatch reactors. In Figure 12.3(a), depicting a homogeneous liquid-phase reaction of the type A + B - products, reactant A is initially charged to the vessel, and reactant B is added at a prescribed rate, as reaction proceeds. In Figure 12.3(b), depicting a liquid-phase reaction in which a... 

Equipment in which homogeneous reactions are effected can be one of three general types the batch, the steady-state flow, and the unsteady-state flow or semibatch reactor. The last classification includes all reactors that do not fall into the first two categories. These types are shown in Fig. 4.1. 

The idea of separating homogeneous TMCs with solvent-resistant NF(SRNF) membranes has only emerged over the last decade with the advent of commercial SRNF membranes. A nondestructive, energy efficient separation and concentration of reusable catalysts from reaction products can thus be realized. The SRNF-coupled catalysis can be run continuously, or alternatively in a semibatch operation mode to lower reactor occupancy or when reaction conditions are too harsh to be membrane compatible. Precipitating by-products could be simply removed from the reactor after filtration before refilling it. 

You are asked to design a semibatch reactor to be used in the production of specialized polymers (ethylene glycol-ethylene oxide co-polymers). The semi-batch operation is used to improve the molecular-weight distribution. Reactant B (EG) and a fixed amount of homogeneous catalyst are charged initially into the reactor (the proportion is 6.75 moles of catalyst per 1000 moles of Reactant B). Reactant A (EO) is injected at a constant rate during the operation. The polymerization reactions are represented by the following liquid-phase chemical reactions ... 

Oxidation of aqueous phenol solutions was studied over various catalysts in a semibatch slurry and continuous-flow fixed-bed reactors at temperatures up to 463 K and pressures slightly above atmospheric. The results show that due to a complex consecutive-parallel reaction pathway and a heterogeneous-homogeneous free-radical mechanism both kinetics and reaction selectivity are strongly dependent on the type of reactor used. Although the catalysts employed were found to be active in converting aqueous phenol solutions to nontoxic compounds, neither metal oxides nor zeolites were stable at the reaction conditions. 

In a kinetic investigation of the catalytic liquid-phase phenol oxidation carried out in a semibatch slurry reactor [6], it has been found that homogeneous stepwise polymerization reactions are enhanced in the bulk liquid-phase due to the high liquid-to-solid volumetric ratio. The rate of phenol disappearance has been expressed on the basis of power-law kinetics as a sum of heterogeneous and homogeneous (polymerization) contributions, thus... 

Different types of reactors are applied in practice (Figure 1.14). Stirred tank reactors (STR), very often applied for homogeneous, enzymatic and multiphase heterogeneous catalytic reactions, can be operated batchwise (batch reactor, BR), semi-batchwise (semibatch reactor, SBR) or continuously (continuous strirred tank reactor, CSTR)... 

A well-mixed batch reactor whose contents are regarded as pseudo-homogeneous in temperature and composition throughout the entire volume occupied by the suspended cells. Aerobic bioreactions are often carried out in a semibatch mode of operation in which oxygen or air is bubbled continuously through the... 

Homogeneous batch and semibatch reactor Differential Homogeneous tube reactor Differential... 

As an example, let us consider suspension polymerization. In suspension polymerization, the monomers from the monomer droplets transfer into the polymer particles as long as monomer droplets exist. Thus, regarding the change of monomer concentration in the space of polymerization, that is, polymer particles, this reaction can be considered a semibatch reactor from the viewpoint of the change of monomer concentration. Figure 10 depicts the calculated results of crosslink density distribution of suspension polymerization and homogeneous phase polymerization under Flory s simplified conditions [48, 49]. In Fig. 10, the abscissa indicates the reactivity (0) at ttie time of each primary polymer formation and the ordinate shows the probability of crosslink density of each primary polymer. In the figure, for example, the line with l/ = 0.6... 

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