Temperatures, industrial before intermediate

The most significant development has been the introduction of fluidized bed conversion. One fluid bed replaces the three beds before intermediate absorption in the double absorption set-up. In a fluidized bed converter the gas flow is reversed and the catalyst becomes fluid or movable. The heat transfer properties are then much greater than for fixed beds and internal boiler tubes can control the temperature to within a degree in the 460-500 °C range. This technique has not been used except as a prototype because of the parlous state of the industry following recession. 

In redox initiation, the free radicals are generated as transient intermediates in the course of a redox reaction that involves an electron transfer process followed by scission to give a free radical. The features of redox initiation, that particularly lend themselves to industrial processes, are the general lack of any induction period before polymerisation begins and a relatively low energy of activation. The low energy of activation allows polymerisation to be carried out from, or at, low temperatures, and this facilitates reaction control of a very exothermic process. 

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