Patent EP-3611162-A1 (EP)
Inventor: ICHIOKA RYOJI
IPC: B01D3/14
Filed: 2018-01-05
Abstract: The present invention relates to a method for distilling a liquid containing dimethyl sulfoxide using a distillation equipment, including: 
(1) mixing sodium carbonate with a liquid containing dimethyl sulfoxide at a bottom of the distillation equipment such that sodium carbonate accounts for 0.005% to 25% by weight relative to 100% by weight of the liquid containing dimethyl sulfoxide and sodium carbonate in total at the bottom of the distillation equipment and heating the bottom; and 
(2) obtaining a distillate containing dimethyl sulfoxide at a position that is lower than a position at which the liquid containing dimethyl sulfoxide is initially introduced and higher than a position of the heated portion. 
According to the method for distilling dimethyl sulfoxide of the present invention, a compact equipment is achieved, and thus, the system construction investment cost is low. Further, as the temperatures of an in-process liquid and vapor in a distillation tower can be raised up, it is possible to reduce the amount of energy used in the system as a whole by reusing energy through recovery of sensible heat and latent heat of the in-process liquid and vapor. This allows distillation purification of dimethyl sulfoxide at a low purification cost in an economical manner. 
Dimethyl sulfoxide obtained by the method for distilling dimethyl sulfoxide of the present invention contains fewer impurities and has high purity. Dimethyl sulfoxide obtained by the method for distilling dimethyl sulfoxide of the present invention can be used as a liquid for removing photoresists as electronic materials, a liquid for synthesis of medicines and pesticides, a liquid for removing washing lend molds or the like, a solvent used in a step of polymerization of polymers such as cellulose, polyimide, polysulfone, polyurethane, and polyacrylonitrile or spinning of fibers of such polymers, or a liquid for removing paints. 
The present invention relates to a multistage distillation tower for distilling a liquid containing dimethyl sulfoxide, which includes an apparatus for adding sodium carbonate at a tower bottom of the distillation tower, and 
which is provided with a system capable of mixing sodium carbonate with a liquid containing dimethyl sulfoxide at the tower bottom of the distillation tower while controlling the concentration of sodium carbonate to 0.005% to 25% by weight relative to 100% by weight of the liquid containing dimethyl sulfoxide and sodium carbonate in total at the tower bottom of the distillation tower and heating the bottom portion, 
wherein a side cut for allowing a distillate containing dimethyl sulfoxide to be drawn off at a position that is lower than a position of a supply stage for supplying a liquid containing dimethyl sulfoxide and higher than a position of the heating portion. 
According to the multistage distillation tower of the present invention, as the temperatures of an in-process liquid and vapor in a distillation tower can be raised up, it is possible to reduce the amount of energy used in the system as a whole by reusing energy through recovery of sensible heat and latent heat of the in-process liquid and vapor. This allows distillation purification of dimethyl sulfoxide at a low purification cost in an economical manner. 
Dimethyl sulfoxide recovered or purified according to the multistage distillation tower of the present invention contain fewer impurities and has high purity. Dimethyl sulfoxide according to the method for distilling dimethyl sulfoxide of the present invention can be widely used as a solvent for removal or washing of electronic materials, synthesis of medicines and pesticides, polymer polymerization, spinning of fibers of such polymers, and the like.