METHOD FOR PRODUCING FORMALDEHYDE GAS AND APPARATUS FOR PRODUCING FORMALDEHYDE GAS

摘要

PROBLEM TO BE SOLVED: To provide a technology for reducing a content of water included in a formaldehyde gas while preventing deterioration in final purity and productivity of the formaldehyde gas and preventing great increase in production cost.SOLUTION: A method of producing a formaldehyde gas includes: a first process of reacting alcohol (A) with a formaldehyde aqueous solution (B) to produce a hemiformal aqueous solution (C); a second process of evaporating water included in the hemiformal aqueous solution (C) to separate a hemiformal concentrate (D) and water (E); a third process of bringing the hemiformal concentrate (D) into contact with a porous absorbent to remove water in the hemiformal concentrate (D) to isolate a high-purity hemiformal concentrate (F); and a fourth process of thermally decomposing the high-purity hemiformal concentrate (F) to produce the formaldehyde gas (G).