4068 Words Mar 29th, 2014 17 Pages
Sulphonation – The Process
Most electrophilic substitution reactions are irreversible but sulfonation is an exception. Treatment of benzene with "oleum" (a solution of SO3 in concentrated sulfuric acid) will give the sulfonic acid, the electrophilic species being sulfur trioxide which is Lewis acidic. Fig – 1 Sulphonation : Benzene equation
The sulfonic acid can be converted back by treatment with hot aqueous acid. The reason for this reversibility is the fact that the Wheland intermediate is overall neutral and therefore more stable than other, positively charged intermediates. Hence, under forcing reaction conditions, the energy difference in progressing in either the forward or backward sense from the Wheland intermediate is
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Bulk Density: 700kg/dm3 approx...

The regeneration is carried out by heating with air at 150 degree Celsius. A checking about the effective regeneration is made by verifying the Silica gel indicator through the sight glasses, as well as by verifying the outlet temp., of the regeneration air on the recording thermometer. When the regeneration is accomplished the silica gel mass has a temperature quite near 150 degree Celsius. Therefore it is necessary to cool the silica gel thus allowing it to adsorb the humidity of the air crossing it.

Note – The four way valves are provided with a drive by pneumatic cylinders which are remote controlled energizing some solenoid valve suitably.

Air drying and cooling

Air that is utilized in the production of LABSA has to be cooled first and then dried to ensure its feasibility for further reactions. Air is cooled by passing it through a heat exchanger containing the coolant mono-ethylene glycol; at a temperature of 0 to -2 degree Celsius. The coolant ensures condensation of air to around 5 degree Celsius.

After cooling air to the required temperature it has to be dried to remove traces of moisture present in it. For this purpose air is passed through a cylinder filled with silica gel. The silica-gel brings the dew point of the water in the air down to stay -40 degrees Celsius. This means that the air is dry as if the air was cooled down to -40 degrees Celsius. In practice two cylinders with silica-gel are used; one for
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