| 摘要 |
<p>A stabilized aqueous solution of formaldehyde containing 15-60% by weight of water is prepared by introducing cyanuric acid during the formation of the solution in such an amount that the prepared solution contains 3-8 moles of formaldehyde per mole of cyanuric acid. An aqueous solution of formaldehyde which is dilute enough to be stable may be first prepared, cyanuric acid then added and water evaporated until the solution contains 15-60% of water. Alternatively the stable solution may be continuously prepared by supplying formaldehyde-containing gas to an absorption system comprising two or more stages; in the first stage the gas is washed with an aqueous solution of formaldehyde and cyanuric acid and in the last stage gas not absorbed in the preceding stage(s) is washed in counter-current with water, the solution resulting from the absorption in the stage(s) after the first is used in conjunction with part of the solution produced in the preceding stage as washing liquid in that stage and the part of the solution produced in the first stage which is not recirculated is discharged from the system as final solution.</p> |
