New reactor in jet spouted bed regime for catalytic polymerizations

Abstract

The hydrodynamic features, suitable for catalytic polymerization in the gaseous phase, of a new reactor in the jet spouting regime have been studied. This regime is reached by expansion of conical spouted beds. The application of the jet spouted bed as a reactor in catalytic polymerizations implies the treatment of sticky solids with a wide particle size distribution, even of catalyst particles of reduced size (less than 1 mm diameter), which are not habitually treated in conventional spouted beds. The jet spouted bed has a high stability and reduced segregation together with a great capacity for continuous operation of the solids. In a pilot-plant scale unit, the following original aspects of the gas-solid contact have been studied: the design factors for stable operation (contactor angle, ratio between the inlet diameter and the base diameter of the contactor, ratio between the inlet diameter and the particle diameter); the hydrodynamics (correlations for the calculation of the minimum velocity, of the stable operation pressure drop and of the maximum pressure drop); the proposal of a disperse plug flow model for the gas in the reactor, and the subsequent calculation of the dispersion coefficient. The behaviour of the jet spouted bed as a reactor in the polymerization of benzyl alcohol has been studied in an automated laboratory unit where the effect of the residence time of the catalyst and the alcohol concentration in the feed have been analysed.