Study On The Hydrolysis Of Methyl Acetate Catalyzed By Cation Exchange Resin

Polyvinyl alcohol (PVA) is a useful polymer which can be converted into various products. But the producing of PVA is followed by plenty of byproduct -methyl acetate (MeOAc), at a ratio of about 1 .7 tons of MeOAc per ton of PVA. In industrial PVA plants, MeOAc is usually hydrolyzed to methyl alcohol (MeOH) and acetic acid (HOAc) for recycle to produce PVA. So it is significant to study the hydrolysis of MeOAc.In this paper, the macroscopic kinetics of hydrolysis of MeOAc, catalyzed by catalyst capsule and particulate catalyst of G- 6104 cation exchange resin were investigated respectively.Firstly, reaction rate without external and pore diffusional resistances was measured in a stirred batch reactor. The rate data fits the following model:The parameters of the model were estimated by using non- linear least square. Comparing calculated values from the model with experimental results, the errors are small, and variance predicted by the model conforms to experimental variance. So the model is very suitable. Moreover, it was found the reaction mechanism could be explained by Langmuir - Hinshelwood adsorbing theory, and the ratedetermining step is surface reaction between adsorbed molecules of methyl acetate and unadsorbed molecules of water(single site mechanism).Meanwhile , effect of reaction temperatures catalyst loading and mole ratio of water to MeOAc on the conversion of MeOAc was studied. Conversion of MeOAc increases with increasing of reaction temperature,catalyst loading and mole ratio of water to MeOAc. Arrhenius relationship of reaction constant and reaction temperature, and activation energy E were obtained:Then, a circulating bath reactor, in which liquid flow is in the similar way as in a catalytic distillation column, was designed to measure the effectiveness factor of catalyst capsule. The experienced correlation of the effectiveness factor and liquid rate was obtained.Finally, The hydrolysis of MeOAc in an experimental catalytic distillation column was investigated. Conversion of MeOAc decreases with the increase of feed rate, and the position of feed has effect on the conversion. Water entering the column at the top of reaction zone and MeOAc feeding at the bottom of reaction zone is best.