Patent ID: 7819944

Claim:
A dehydration method by which water is selectively separated from a water-containing mixture with a separation membrane that is a DDR type zeolite membrane, the dehydration method using pervaporation or vapor permeation comprising: bringing the mixture into contact with one side of the DDR type zeolite membrane, wherein the mixture is a liquid containing an organic compound at ambient temperature and pressure; and causing a pressure difference between a supply side of the DDR type zeolite membrane which is in contact with the mixture and a permeation side of the DDR type zeolite membrane, to thereby cause the water to selectively permeate and separate out, wherein a pressure on the permeation side is lower than that on the supply side, and (i) when pervaporation is used, a pressure of the permeation side of the DDR type zeolite membrane is in a range of 1×10 −1 to 1×10 4 Pa, and (ii) when vapor permeation is used, a pressure on the permeation side of the DDR type zeolite membrane is in a range of 1×10 −2 to 5×10 4 Pa.