Efficient removal and reusage of acid soluble oil in waste H2SO4 of isobutane alkylation by low-temperature carbonization process

Abstract

Waste H₂SO₄ from industrial isobutane alkylation, a hazardous thick liquid with a high concentration of acid soluble oil (ASO) impurities, poses challenges in the regeneration process. Herein, an innovative low-temperature carbonization process was proposed to convert waste H₂SO₄ into the regenerated concentrated H₂SO₄ and sulfonated activated carbon materials (SACMs) under mild reaction conditions. The optimal reaction temperature is identified at 423.15 K with the highest total organic carbon (TOC) removal of 90.57%. The high-purity regenerated H₂SO₄ with a concentration of 95% as a catalyst for isobutane alkylation exhibits excellent catalytic performance with 94.54 research octane number (RON) of the alkylate. SACMs, characterized as a novel porous carbon material with plentiful hydroxyl, carboxylic acid, and sulfonic acid functional groups, demonstrate an efficient catalytic activity in the dimerization of lactic acid to produce lactide with a yield of 46.95%. Hopefully, the novel recovery process provides a promising application to optimize the regeneration process of waste H₂SO₄ from industrial isobutane alkylation.