Development and modelling of a new catalytic distillation process.

摘要

Catalytic Distillation (CD) is a relatively new process used by the petrochemical industry. The process involves placing a heterogeneous catalyst inside of a distillation column so that a chemical reaction and product separation can take place simultaneously in the same piece of equipment.; This thesis describes a new application of CD for the production of diacetone alcohol (DAA) via the base-catalyzed aldol condensation of acetone. An important goal of this thesis is to develop a new model of CD that takes into account mass transfer between the catalyst and the liquid phase.; In order to develop a model of CD, an experimental program was completed to obtain basic data for reaction kinetics and mass transfer. Mass transfer experiments were also conducted. The rate of mass transfer between the liquid and the catalyst, however, was found to be extremely sensitive to the flow pattern which is established in the column. Several CD experiments were conducted in the bench scale and pilot scale CD facilities at the University of Waterloo.; A differential rate-based model was developed which describes the reaction zone of the CD column. The model takes into consideration the kinetic data obtained in the absence of external mass transfer and modifies the kinetic equations to incorporate the various types of external mass transfer which exist in the CD column. The model was fitted to the CD operating data so that the rate of DAA production predicted by the model matched the experimental data. Agreement between the model and other experimental variables which were not fitted was very good. The predicted flow patterns were in agreement with the earlier work of Porter and Templeman (1968), and the model was also able to provide a good estimate of the expected product selectivity and MO production rate. Several samples from within the catalyst bag were also taken, and they confirmed that the predicted concentration profiles in the catalyst bag were close to measured values.; Several experiments were conducted with a proper liquid distributor located just above the catalyst zone of the column. Improving the liquid distribution over the catalyst bag resulted in 45-240% gains in DAA production and 112-343% gains in product selectivity (measured as mol DAA/mol MO). The distributor also reduced the variability of the system. Clearly, liquid distribution and mass transfer are two of the most important issues in catalytic distillation.; A major problem encountered with this process is catalyst deactivation. If a catalyst can be found that has improved lifetime characteristics, the production of DAA with Catalytic Distillation could easily be commercialized. (Abstract shortened by UMI.)