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2.5.13 Sulphonation with SO3
[15, Köppke, 2000]
For environmental issues and the treatment of waste streams, see Section 4.3.2.9.
Chapter 2
Sulphonation with SO3 is applied in the manufacture of a smaller number of aromatic sulphonic
acids produced in higher volumes.
Chemical reaction
Sulphonation with SO3 is illustrated in Figure 2.27. The reaction does not lead to the formation
of reaction water and shows higher selectivity if carried out at lower temperatures.
Figure 2.27: Sulphonation with SO3
Side reactions:
• formation of sulphones
• formation of isomers
• formation of oxidation by-products.
R
H SO 3H
+ SO 3
If carried out as a liquid phase reaction, halogenated compounds serve as solvents (e.g.
methylene chloride or dichloroethane).
Operations
Figure 2.28 and Figure 2.29 show typical sequences of operations, possible input and related
waste streams from the reaction in liquid phase and the gas-liquid reaction.
Liquid phase reaction
Both, the organic feed and SO3 are
dissolved in organic solvents (e.g.
methylene chloride or dichloroethane)
and continuously added to the reactor.
On completion, the reaction mixture is
transferred into water and cooled. The
organic phase is segregated and the
product is precipitated from the aqueous
phase by cooling and addition of
sulphuric acid with subsequent
filtration.
OFC_BREF Dezember 2005 61
R
Gas-liquid reaction
Depending on the local conditions, SO3 gas
is derived directly from a sulphuric acid
facility or generated by combustion of
sulphur. The reaction is usually carried out
in falling film reactors. In many cases, it is
not necessary to perform further work-up
steps.