Method of recovery acid catalyst from acid catalyzed processes

#The present invention concerns acid catalyzed hydrocarbon conversion processes, and, more particular, recovery of valuable acid catalysts from a product stream leaving a hydrocarbon conversion process.

#Acid catalyzed processes are most usually employed in the industrial isomerization and hydration of hydrocarbons and during the preparation of high octane gasoline products by alkylation of paraffinic hydrocarbons.

#In those processes, a strong acidic compound is conventionally mixed with a hydrocarbon feedstock in a reaction vessel and agitated for a sufficient time until the desired reaction is completed. The final product containing, furthermore, the acid catalyst is then recovered from the reactor effluent by extraction or distillation.

#Recovery of trifluoromethanesulphonic acid catalyst from an alkylated product stream.

#A product stream from alkylation of i-butane with 1-butene alkylating agent in the presence of trifluoromethanesulphonic acid catalyst was treated for the recovery of the acid catalyst by adsorption and desorption on a silica adsorbent according to the invention. The product stream leaving the alkylation process contained 30-100 ppm of the acid catalyst and was passed through an adsorption column loaded with 500 ml of the silica adsorbent (Silica Gel 100, particle size 0.2-0.5 mm, as supplied by E. Merck, FRG).

#At an inlet temperature of 15.degree. C. and a flow of 7 kg/hour of the product stream through the column, substantially all of the acid catalyst in the product stream was adsorbed on the adsorbent resulting in an effluent stream from the adsorption column with an acid concentration of below 1 ppm. After passage of about 46 kg product stream through the column, the acid concentration in the effluent stream was still below 1 ppm. The concentration of non-adsorbed acid raised to 5 ppm upon passage of 98 kg product stream. After 975 kg product stream have been passed through the column, 20 ppm acid catalyst were found in the effluent stream. The flow of product stream through the column was then stopped. In a subsequent desorption cycle, adsorbed acid was desorbed into an alkylation process stream with 10 vol % 1-butene in i-butane. By passage of 2.8 kg process stream at 40.degree. C. through the column, most of the adsorbed acid was recovered.