Plants for continuous sulfation and sulfonation

The reduced operating costs and the high product quality guaranteed by our sulphonation plants have made IIT the preferred supplier of the most important surfactant and detergent manufacturers worldwide.
Sulphonation plant by IIT: sulfonation reactor, dioxane stripping unit, SO2 to SO3 converter

Overview of the manufacturing process

Organic sulfates and sulfonates are industrially manufactured by reacting organic compounds (alkybenzenes, fatty alcohols, ethoxilated fatty alcohols, methyl esters, alfa-olefines, etc.) with diluted gaseous SO3. The reaction is called sulfation or sulfonation depending on the functional group created in the reaction product: sulfates R–O–SO3H or sulfonates R–SO3H.
The sulfonic acids obtained by processing some alkylates (most notably: LABSA) can be marketed as such, as they can find direct industrial application. Otherwise, the organic acids coming either from sulfation or sulfonation reaction are neutralized to form the relevant organic salts (most notably: SLES, SLS, LABS and AOS). A finishing phase is required in order to remove possible impurities produced by secondary reactions (e.g.: dioxane and sultones), as well as to stabilize, homogenize and dilute the products.
The products of IIT sulphonation plants find prominent application as cleaning and foaming agents in detergents, as well as wetting and emulsifying agents in dyes, pigments, medicines, pesticides, etc.

sulphonation plant flow diagram - LABSA, LABS, SLES, SLS, AOS manufacturing

Gaseous SO3 production

Gaseous SO3 can be produced either by sulfur burning or by liquid SO3 evaporation, respectively best suited for industrial and small-sized plants.

IIT highly reliable sulfur furnaces guarantee continuous SO3 production for long periods of time. They can be coupled either with a direct or indirect heat recovery system.

The gaseous SO3 needed for the sulfonation reaction must be produced with very dry air. The special design of IIT desiccant driers guarantees that the dew point of dried air permanently remains lower than −70°C. This makes the installation of an oleum demister unnecessary, eliminating all the problems introduced by this device, such as pressure drop, SO3 surge, maintenance difficulties and delayed startup.
IIT air dryers are desiccant-type: they rely on two towers filled with desiccant material, alternating between air drying phase and desiccant regenerating phase. IIT air dryers are equipped with an autonomous regeneration system that allows to regenerate the desiccant material also before the plant startup, when external hot air isn't available.

Gaseous SO3 production from liquid sulfur
Desiccant air dryer
Sulfur furnace (right) with steam boiler for heat recovery (left)
SO2 to SO3 converter

Sulfation and sulfonation

Perfected in years of research, IIT proprietary sulfonation reactor is a multi-tube falling film reactor with unique features.

IIT sulfonation reactor allows to treat the vast majority of sulfatable or sulfonatable raw materials obtaining the best product quality. Alkylates, fatty alcohols, ethoxilated fatty alcohols, alfa-olefines and methyl esters are just some of the possible compounds that can be sulfated or sulfonated by IIT reactor.

Sulfonation reactor models
# of tubes 1 24 36 48 60 72 84 112
kg/h (LABSA) 5 1000 1500 2000 2500 3000 4000 5000
IIT sulfonation reactor, with inputs and outputs shown on the right
Reactor body (36 tubes model, with capacity 1500 kg/h)
Organic compound distribution plate
Sulfonation reactor in a surfactant production plant, supplied during 2001


The key equipment of IIT neutralization technology is the proprietary continuous in-line high shear mixer homogenizer. This equipment is suitable for different operations, including blending, mixing, emulsifying, solid suspending or dispersing, dissolving, diluting, homogenizing, miling and accelerating reactions.

The mixing action is performed through a 'rotor/stator high-shear group'. The rotor turns at high speed forcing the liquid through small interstices. Product (liquid and some solids) is subjected to intense mechanical and hydraulic shear action by the high speed of the rotor, ensuring a very homogenous mixing.

High shear mixer with rotor and stator made of Teflon
High shear mixer homogenizer with rotor and stator made of steel

Exhaust gas cleaning

Gases leaving the reactor contain mists of organic sulfonic and sulfuric acid as well as sulfur dioxide (byproduct of sulfur combustion) and therefore they cannot be directly discharged into the atmosphere.

IIT electrostatic precipitators have been specifically designed to remove acid mists from the exhaust gases of sulfonation plants. They feature an original, simple system for easy and fast electrode installation and centering and they can be equipped with an optional washing system of the collecting tubes.

IIT SO2 scrubbers are packing towers for the removal of SO2 and SO3 from exhaust gases. They're built in plastic materials, in order to avoid corrosion, and they're equipped with a recycle pump, a liquid phase distribution system and all necessary monitoring equipment (pressure, pH, etc.).

ESP models
# of tubes 31 43 55 73 91
kg/h (LABSA) 1500 2000 3000 4000 5000
Two IIT electrostatic precipitators
Caustic scrubber

Product finishing

IIT manufactures equipment for Dioxane reduction, AOS hydrolysis, as well for degassing, diluting and adjusting the qualities of active surfactants.

Our DeDiox system is designed for the reduction of 1.4-dioxane from 70% SLES paste. The DeDiox system can be added to the plant as a standalone unit or integrated into the neutralization unit, even in already existing plants.

During the sulphonation of Alpha Olefins, secondary reactions produce Sultones. These cyclic compounds can be converted to AOS by ageing the product at high temperature for about an hour. IIT supplies complete hydrolysis units, that consist of a feeding pump, a heater, a pressure tank (for holding the product at the required temperature) and a cooler.

IIT dilution equipment has been specifically designed to treat Active Matter surfactants. The surfactants have, in an intermediate concentration range, a very high viscosity that makes their manipulation difficult. The concentrated surfactant and the water are fed to an intensive high-shear mixer of small volume that makes the dilution instantaneous and complete.

Equipment for final adjustment of product quality, i.e. color, pH, stability, etc. may optionally complete the plant.

DeDiox system with two flash tanks and one vapor condenser
Continuous degasser
Skid unit for SLES paste dilution