Cumene bubble column reactor

The oxidation is mostly carried out in traditional bubble column reactors series of two to six reactors, up to 20 m high, are common in industry. The reaction is exothermic 120kJ are released per mole of produced hydroperoxide, and must be removed by cooling. The final reaction mixture, containing 20-30% of cumyl hydroperoxide, is then concentrated by distilling off some unreacted cumene to obtain a 65-85% hydroperoxide to be fed to the cleavage step (Figure 13.2). 

Over the last decades, the reactor design for cumene oxidation made tremendous progress. In the beginning, aerated stirred-tank reactors were used for cumene oxidation [49], at present state-of-the-art bubble column reactors are used. 

Bubble column reactor 2 Gas separator 3 Cumene column 4 Cleavage reactor 5 Catalyst separation vessel 6 Acetone column 7 Cumene/methylstyrene colunrn 8 Phenol column 9 Hydrogenation reactor 10 Waste gas purification 11 Cracker... 

The oxidation of cumene to CHP is a slow reaction. As a rule of thumb, the mean residence time in a continuously operated process is around 10 h at temperatures in the range of 80-120°C. Thus, large bubble columns are preferred for this purpose with, for example, three reactors arranged in series [9]. A cascade of only two reactors [22] or even four reactors [23] is also used in commercial plants. The bubble columns are operated at high pressures ranging from atmospheric to approximately 700 kPa. 

Cumene or cumene/CHP from a reactor upstream is combined with an external circulation flow and enters the bubble column at the bottom. Air is fed through a gas distributor. The off-gas and the liquid product can leave the reactor at the top. The liquid phase in the reactor is well mixed. Therefore, the heat from reaction can be easily removed by an external heat exchanger, as described in [20]. 

Besides bubble columns, other reactor types are investigated. Using a high-shear device creates a high air/oxygen—cumene interface, which increases CHP formation by increased oxygen mass transfer [52]. 

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