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

Waste H 2 SO 4 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 H 2 SO 4 into the regenerated concentrated H 2 SO 4 and sulfonated activated carbon materials (SACMs) under mild reaction conditions. The optimal reaction temperature is identified at 423.15 K with the highest TOC removal of 90.57%. The high-purity regenerated H 2 SO 4 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 H 2 SO 4 from industrial isobutane alkylation. • The carbonization of ASO is the primary reason for the high degradation performance. • The optimal reaction temperature is 423.15 K for H 2 SO 4 recovery with the highest TOC removal at 90.57%. • SACMs with plentiful functional groups are efficient at the dimerization of lactic acid to produce lactide. • The differences in catalytic effectiveness of the high-purity regenerated H 2 SO 4 is caused by ASO.