| 摘要 |
<p>Provided is a technique for decreasing the amount of water contained in a formaldehyde gas without lowering the purity and the productivity of the final formaldehyde gas, while suppressing a significant increase in the production cost. Adopted is a method for producing a formaldehyde gas, which comprises: a first step wherein (A) an alcohol and (B) an aqueous formaldehyde solution are reacted with each other, thereby producing (C) an aqueous hemiformal solution; a second step wherein the water content contained in (C) the aqueous hemiformal solution is evaporated, thereby separating the aqueous hemiformal solution into (D) a hemiformal concentrate and (E) water; a third step wherein (D) the hemiformal concentrate is brought into contact with a porous adsorbent, thereby removing the water content in (D) the hemiformal concentrate and separating out (F) a high-purity hemiformal concentrate; and a fourth step wherein (F) the high-purity hemiformal concentrate is thermally decomposed, thereby generating (G) a formaldehyde gas.</p> |
