Sulfuric chloride separation and purification technique

The invention discloses a technique for separating and purifying sulfuric chloride from a trifluoro-acetyl chloride production reaction waste liquid by a double-tower rectification process. The technique can obtain the high-purity sulfuric chloride product, and has the advantage of low production cost. The prepared sulfuric chloride can be used for chlorination of aromatic compounds and the like.