| 摘要 |
1,240,254. Pentaerythritol. KOEI CHEMTCAL CO. Ltd. 24 Feb., 1969 [2 March, 1968], No. 9854/69. Heading C2C. A process for the continuous production of pentaerythritol comprises arranging a series of two or more upright cylindrical reactors connected successively; each reactor consisting of a mixing part, a cooling part and a reaction part, continuously feeding a mixture of formaldehyde and an alkaline condensing agent to the mixing part of the first reactor and passing-the reaction mixture through the series of reactors successively, while continuously feeding acetaldehyde to the mixing part of each reactor, the residenc e time of the reaction mixture in the mixing par t being less than one minute, the ratio of the height to. diameter of the reaction part being 7 or more, (thus giving plug flow) the residence time of the reaction mixture in each reactor being 5 to 30 minutes and optionally more than 30 minutes up to 1 hour in the final reactor, the linear velocity in the reaction part being higher than 0À2 m./min., the reaction product solution coming out of the final reactor being neutralized with formic or sulphuric acid, and the neutralized solution being concentrated under normal or superatmospheric pressure in a first stage and then under reduced pressure in a second stage. Each reactor may consist of a mixing part, a cooling part and a reaction part integrally arranged successively in the upward direction, or cooling means may be provided in the mixing part. The vapour of ECHO and H 2 0 from the top of the distillation tower in the first stage may be used as a steam source for the second concentration stage- and then recycled to the first reactor. |
