| 摘要 |
A method for recovering sulfuric acid is provided to recover sulfuric acid from gas containing SO3 involving the absorption of the sulfuric acid efficiently, even without high-cost processes, such as electrolysis and thermal treatment of high temperature. A source stream(1) containing sulfuric acid vapor and/or sulfur trioxide is contacted with an ionic liquid absorbent in an absorption stage. A gas substantially free from sulfuric acid vapor and/or sulfur trioxide is recovered from the absorption stage. A stream containing the ionic liquid absorbent(3) is recovered from the absorption stage, wherein the ionic liquid absorbent contains sulfuric acid. The sulfuric acid is recovered from the ionic liquid absorbent by passing the recovered stream through a separation stage. The stream containing abundant sulfuric acid is recovered from the separation stage. An ionic liquid absorbent stream, where the ionic liquid absorbent contains sulfuric acid, is recovered from the separation stage, and the recovered ionic liquid absorbent stream is returned to the absorption stage. Further, the ionic liquid absorbent contains a pyrosulfate less than 5 wt.
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