Recovery of water-free methanesulfonic acid from the bottom stream of a distillation column

A process for separating anhydrous methanesulfonic acid from a reaction mixture comprising methanesulfonic acid and sulfuric acid by distillation, comprising

• feeding the reaction mixture into a first column K1 and producing a top stream of column K1 and a bottom stream of column K1,
• transferring the top stream of column K1 to a second column K2, in which purified anhydrous methanesulfonic acid is obtained from a bottom stream of column K2, and
• transferring the bottom stream of column K1 to either a third column K3 or an evaporator W3-1, in which a top stream of column K3 or a top stream of evaporator W3-1 is recycled back into column K1, and in which a bottom stream of column K3 or a bottom stream of evaporator W3-1 is separated from the distillation process.