Process for regenerating fluorosulfuric acid catalyst

In an alkylation process which comprises:

• a. contacting an olefin with a paraffin in an alkylation zone under alkylation conditions and with a catalyst comprising fluorosulfuric acid to form a reaction mixture of fluorosulfuric acid catalyst phase containing an organic sludge formed during said process and a hydrocarbon phase containing alkylate product;
• b. separating said hydrocarbon phase containing alkylate product from said fluorosulfuric acid catalyst phase, said hydrocarbon phase containing a portion of the fluorosulfuric acid;
• c. washing said hydrocarbon phase with an acid comprising sulfuric acid thereby removing at least a portion of the fluorosulfuric acid from said hydrocarbon phase and separating a sulfuric acid phase containing said fluorosulfuric acid from said hydrocarbon phase containing the alkylate product, the improvement which comprises regenerating said acid catalyst phase according to the following steps:
• d. stripping a portion of the fluorosulfuric acid from the acid catalyst phase separated in step (b) with a paraffin to form a stripped acid phase containing fluorosulfuric acid and organic sludge and a gaseous phase containing said paraffin and fluorosulfuric acid;
• e. contacting said stripped acid phase formed in step (d) and the sulfur acid phase separated in step (c) with water to form an acid-water mixture, thereby converting at least a portion of the fluorosulfuric acid contained therein to hydrogen fluoride and sulfuric acid;
• f. stripping at least a portion of the hydrogen fluoride from said acid-water mixture formed in step (e) with a paraffin to form a gaseous phase comprising hydrogen fluoride and paraffin and a liquid phase comprising sulfuric acid and organic sludge;
• g. passing the gaseous phases formed in step (d) and step (f) into a contacting zone and cooling said phases therein with liquid paraffin to form a liquid-vapor mixture comprising a liquid phase containing fluorosulfuric acid and a vapor phase containing hydrogen fluoride, fluorosulfuric acid and paraffin;
• h. treating the vapor phase formed in step (g) in said contacting zone with at least a stoichiometric amount of liquid sulfur trioxide based on hydrogen fluoride, a portion of said liquid sulfur trioxide being dissolved in a liquid stream of fluorosulfuric acid flowing countercurrent to the flow of said vapor to convert the hydrogen present therein to fluorosulfuric acid, thereby forming a liquid phase of regenerated fluorosulfuric acid and a gas phase containing predominantly paraffin and a minor amount of fluorosulfuric acid;
• i. cooling the gas phase formed in step (h) to a temperature at which substantially all of the fluorosulfuric acid present therein is condensed, thereby forming a liquid phase containing predominantly regenerated fluorosulfuric acid and a gas phase containing substantially pure paraffin, and
• j. using at least a portion of the liquid phase formed in step (i) as said liquid fluorosulfuric acid stream in step (h).

In an alkylation process which comprises:

• a. contacting an olefin with a paraffin in an alkylation zone under alkylation conditions and with a catalyst comprising fluorosulfuric acid to form a reaction mixture of fluorosulfuric acid catalyst phase containing an organic sludge formed during said process and a hydrocarbon phase containing alkylate product;
• b. separating said hydrocarbon phase containing alkylate product from said fluorosulfuric acid catalyst phase the improvement which comprises regenerating said acid catalyst phase according to the following steps:
• c. contacting at least a portion of the fluorosulfuric acid phase separated in step (b) with water to form an acid-water mixture, thereby converting at least a portion of the fluorosulfuric acid contained therein to hydrogen fluoride and sulfuric acid;
• d. stripping at least a portion of the hydrogen fluoride from said acid-water mixture formed in step (c) with a paraffin to form a gaseous phase comprising hydrogen fluoride and paraffin and a liquid phase comprising sulfuric acid and sludge;
• e. cooling the gaseous phase formed in step (d) in a contacting zone with liquid paraffin;
• f. treating the cooled gaseous phase of step (e) in said contacting zone with at least a stoichiometric amount of liquid sulfur trioxide based on hydrogen fluoride, a portion of said liquid sulfur trioxide being dissolved in a liquid stream of fluorosulfuric acid flowing countercurrent to the flow of said gaseous phase to convert the hydrogen fluoride present therein to a fluorosulfuric acid, thereby forming a liquid phase of regenerated fluorosulfuric acid and a gas phase containing predominantly paraffin and a minor amount of fluorosulfuric acid;
• g. cooling the gas phase formed in step (f) to a temperature at which substantially all of the fluorosulfuric acid present therein is condensed, thereby forming a liquid phase containing predominantly regenerated fluorosulfuric acid and a gas phase containing substantially pure paraffin, and
• h. using as least a portion of the liquid phase formed in step (g) as said liquid fluorosulfuric acid stream in step (f).