Environmental Engineering Reference
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chlorine. h e chlorohydrin is thereat er dehydrochlorinated, using aque-
ous potassium hydroxide to produce the epoxide. h is route has long been
the main process for producing both ethene oxide and propene oxide. In
the 1940s, the process began to be phased out for the ethane epoxidation
because of the development of a more-ei cient direct epoxidation process
using a silver catalyst [61].
Hydroperoxide processes are based on the peroxidation of an alkane to
an alkyl hydroperoxide. h ese alkyl hydroperoxides then react with pro-
pene, producing propene oxide and an alcohol. A characteristic of these
processes is that, besides propene oxide, a coproduct is produced in a i xed
ratio, usually 2-4 times the amount of propene oxide produced. Currently,
two variants of this process are applied commercially (Figure 8.1).
However, a disadvantage of the hydroperoxide process is the produc-
tion, in a i xed ratio, of a coproduct (either styrene or tert-butyl alcohol,
depending on which variant of the hydroperoxide process is applied).
h e energy required to activate O 2 by splitting it into oxygen atoms is
497 kJ mol-1, even larger than the bonding energy (431 kJ mol -1 ) of the
C-H bond in the most stable hydrocarbon, methane [17, 63]. When such a
large amount of energy is put into the system, it is very dii cult to control
the reactivity of atomically dissociated species of oxygen, and, most likely,
purge gas
lime
propene oxide
light ends
steam
lime
CaCl 2 containing
wastewater
1,2-dichlorpropane
Propene
Chlorine
Water
Figure 8.1 Schematic representation of the chlorohydrin process for the production of
propene oxide. Reproduced with permission from [62].
 
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