Hung-Chung Shen

Internal and External Mass Transfer Effects for Commercial Acid Resin Catalysts in TAME Synthesis

To overcome the drawback of low catalytic performance of reactive packing in a catalytic distillation column, an apparatus comprising an all-V tray and fixed catalyst bed has been developed. In this study, the effects of internal and external mass transfer resistance on the tert-amyl methyl ether (TAME) synthesis catalyzed by acid resin catalysts were investigated to obtain the design criteria in the catalyst bed. Rate equations modified from the work of Rihko and Krause (1995) were used to calculate the reaction rate. The results indicated that the effect of internal mass transfer resistance on TAME formation was insignificant, whereas its effect on TAME decomposition was very significant. At a temperature of 353 K, to achieve a 95% intrinsic rate of TAME formation, the diameter of the resin particles needed to be smaller than 0.9 mm, and the porosity larger than 0.4. Empirical correlation equations were used to calculate the external mass transfer coefficient, which was confirmed by test reactions performed in an isothermal tubular reactor. As suggested by the model calculation results, the external mass transfer resistance over resins could be neglected even if Reynolds number decreased to 0.04 under operation conditions that included a space velocity of 0.06 h^(-1).