Tocopherol In A Fixed Bed Transition

Since a-tocopherol has special biological activities, it is important to convert non-a-tocopherols to a-tocopherol. Experiments were divided into two parts, one was primary research on the fixed bed and the other was ulteriorly research on the fixed bed reconstructed.During the primary research, four influencing factors were considered: the residence time, pressure, temperature and weight ratio of formaldehyde to tocopherols. The results showed that the purity of a-tocopherol in the product was 51% and the conversion of non-a-tocopherol was higher than 80% when we selected acidic ion exchange resin as methylating reaction catalyst. Pd/C as hydrogenation catalyst, and remaining the temperature (as 180癈), the pressure as (5MPa) and the weight ratio of formaldehyde to tocopherols as 2:l(wt/wt), But the selectivity and the yield of a-tocopherol were not high enough.The second part of this work was carried out in the reconstructed fixed bed reactor. The increase of the residence time was in favor of the reaction. High pressure (5MPa and above) was good to the reaction. The optimal temperature was 183 . A preferable weight ratio of formaldehyde to tocopherols was 2:l(wt/wt). And the preferable filled weight ratio of the acidic ion exchange resin to Pd/C was 5:l(wt/wt). The stability of the ion-exchange resin was also investigatd. The results showed that the resin could not keep high activity after running repeatly three times. The ion exchange capability was rapidly decreased when the resin was heated in 190 and above. And we also used toluene-sulfonic acid and Nafion resin instead of the acidic ion exchange resin to catalyse the methylating reaction. The catalysis effects were better than the ion-exchange resin.