| The production of FCC catalyst microspheres by the sol matrix method is a complex process for the prediction of spray-dried particle characteristics. The silica or silica-alumina binder undergoes polymerization and aggregation of primary particles up to and during the spray drying process. Additionally there are many variables which can interact to affect the important chemical and physical catalytic properties.; The applications of silicomolybdate formation and coagulation by gelatin and salt for studying the kinetics of silica-alumina polymerization were investigated. The polymerization of silica-alumina sols in the molecular deposition and aggregation regimes were modeled. The models were used to control the degree of polymerization at the time of spray drying.; Spray dried particle screening runs were performed using a fractional factorial design. The following variables were screened: sol concentration, solids concentration, and degree of polymerization at the times of solid addition and at the time of spray drying. The resulting catalyst particles were characterized using scanning electron microscopy and EDX analysis.; High sol concentrations corresponded to thicker shells, less spherical particles with smoother surfaces, and more void spaces. Increasing the solids concentration decreased the amount of fines produced, and contributed to the formation of thicker shells. Changes in the sol age size did not directly affect any of the responses that were measured. It may be important in interaction with other variables studied. Increasing the batch age size was correlated to increased hollowness and more clay being distributed in the shell. Two-factor interactions were important in the formation of surface roughness, thick shells, hollow particles, uneven clay distribution and clay zones. Because of the fractional factorial design employed the parameters corresponding to the interaction effects could not be resolved. |
