Commercial Processes using Hydrofluoric Acid as Liquid Catalyst

1 Commercial Processes using Hydrofluoric Acid as Liquid Catalyst 

The hydrocarbon mixture from the settler is passed through a depropanizer, deisobutanizer, and debutanizer, consecutively. Usually, the propane and w-butane streams are processed to remove residual hydrofluoric acid and isoalkyl fluorides, while the alkylate product stream is obtained directly at the bottom of the debutanizer unit. From the deisobutanizer and the depropanizer accumulators isobutane and hydrofluoric acid are recycled back to the reactor unit, respectively. In contrast to the flow-sheet above, where three separate fractionators are shown, many alkylation plants use a single separation tower to separate the hydrocarbon mixture into propane, n-butane, and alkylate product fractions and isobutane for recycling. 

The main difference between the Phillips and the UOP Process is a different design of the acid settler-cooler-reactor section The Phillips Process uses a riser-type reactor in which the hydrocarbon mixture is introduced through nozzles. Perforated trays in the vertical reactor provide good dispersion of the hydrocarbon phase in the acid phase. In the setfler the acid is separated from the hydrocarbon phase and recycled hydrofluoric acid is cooled in heat exchangers to remove the heat of reaction. As in this system acid circulation is forced by gravity - an expensive acid circulation pump is not needed. 

2 Commerdal Processes Using Sulfuric Acid as Liquid Catalyst 

The hydrocarbon feed and the acid are introduced into the eye of the impeller and recycled through the outer shell. To remove the heat of reaction and the energy of the impeller, the mixture is pumped through a tube bundle and then sent to the settler section. 

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