Study On Synthesis Of Tert-butyl Acetate By Direct Esterification With Acetic Acid And Isobutene

Qualitative and quantitative analysis methods for reaction products were established through some means including gas chromatography-mass spectrometry, chromatographic analysis and acid-base titration, and the reliability of the analysis methods was verified. Tert-butyl acetate(TBA) was synthesized by direct esterification with acetic acid and isobutylene using three strong acid cation exchange resins A, B and C as catalyst respectively. Effect of space velocity, reaction pressure, acid-isobutylene ratio and reaction temperature on the esterification reaction was studied and made a contrast with A15 catalyst. The results show that influence of process conditions on selectivities of dissolved isobutylene and tert-butyl alcohol is not obvious. As isobutylene is liquid, effect of reaction pressure on conversion of acetic acid, selectivities of TBA and polymers from isobutylene is little. Acid-isobutylene ratio and reaction temperature have a great influence on esterification. C shows the best catalytic activity on esterification with suitable processing conditions as follows:1.0-1.2MPa of reaction pressure,4h-1 of space velocity,4:1 of acetic acid to isobutylene ratio and 17-20℃of reaction temperature. In this case, conversion of isobutylene can achieve 90%, selectivity of tert-butyl acetate can achieve 90% and selectivity of the polymers from isobutylene is less than 10%. Adding water or tert-butyl alcohol to acetic acid can effectively restrain the isobutylene polymers generation and improve the selectivity of tert-butyl acetate. Relatively, the method of adding tert-butyl alcohol to acetic acid is more effective than Adding water in improving the selectivity of TBA and reducing the selectivity of isobutylene to polymers. When adding tert-butyl alcohol to acetic acid by 5.0-6.0%, selectivity of TBA will be close to 100%, selectivity of isobutylene to polymers will drop to 1.5%.Properties of C, B, A and A15 were analyzed. The results show that the exchange capacity of A and B is slightly higher than C and A15, while the specific surface, acid strength are far less than A15 and C. The esterification effect of A15 and C is better than A and B. Resin catalysts with a larger specific surface and higher acid strength will show a better catalytic activity on esterification. According to esterification activity, the order of four kinds of resin catalyst is as follows:C≈A15>B>A, it fits in well with the experimental results.