Process for Recovery and Purification of Isobutane Alkylation Spent Acid
Volume Title: 1
1Department of Oil and Chemical Engineering, Science and Research Branch, Islamic Azad university, Tehran, Iran
2Research Institute of Petroleum Industry (RIPI), Tehran, Iran
3Department of Science and Research branch, Islamic Azad University, Tehran, Iran
4Department of Chemical Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran.
Alkylation of isobutane and butenes was carried out in a semi continuous setup using sulfuric acid as catalyst to produce isooctane. The liquid phase interaction between isobutane and butenes as isobutane alkylation has been investigated at 13℃ and 1 MPa in acidic phase. Spent acid waste is produced at the alkylation process and the petroleum processing industry unit that requires sulfuric acid as a catalyst. Spent acid contains sulfuric acid attached to a long chain carbon and other compounds. This compound is corrosive and has a pH below 1.0, so that it cannot be directly discharged into the environment. The remains of water and organic solvents in sulfuric acid not only reduce the purity of acid but also influence the physicochemical properties and even the results of reactions performed in acid. This study aimed to conduct waste treatment of spent acid and to recover sulfuric acid from the spent acid solution because the level of H2SO4 is high at about 85%, then the sulfuric acid can be reused in the alkylation process. It is found that this new method can break the week inter-molecular bond between acid-hydrocarbons and remove quickly the volatile impurity in acid at mild conditions. The effecting factors of the new method in comparison with the traditional one have been investigated. Olefin conversion and octane number of alkylates were determined. The results showed that the proposed method can easily remove the spent acid’s impurities and the lifetime of the catalytic system was extended to 5 time.