Prague Institute of Chemical Technology Department of Chemical Engineering Center for Nonlinear Dynamics

Catalytic Polymerization Processes

Keywords:

Models of catalytic polymerization processes Slurry tank reactors Loop reactors Growth of polymer particles Modeling of particle growth and morphology Dynamics and stability of polymerization processes

Researches

Juraj Kosek, assistant professor  Dalimil Snita, associate professor  Milos Marek, full professor

Frantisek Stepanek, graduate student  Antonin Novak, graduate student  Zdenek Grof, student  Ingvild Bakken, student

Contact Information

Department of Chemical Engineering  Prague Institute of Chemical Technology  Technická 5  166 28 Prague 6  Czech Republic

Tel: +420-2-2435 3296  Fax: +420-2-311 7335  E-mail: jkk@vscht.cz (Juraj Kosek)

Affiliations

• Department of Chemical Engineering
• Center for Nonlinear Dynamics of Chemical and Biological Systems

Introduction
We focus on the experimental and modeling studies of catalytic homogeneous and heterogeneous polymerization reactors, but non-catalytic processes are also investigated. We are also involved in the design of reactors for the production of new polymer products with tailored properties.

Models of catalytic polymerization processes
Three spatial levels are considered in the description of liquid and gas phase catalytic polymerization reactors:

• Micro-scale: complex reaction kinetics, the presence of comonomers (dienes), several types of active catalyst sites, branching of polymer chains, molecular architecture and population balances of polymer chains.
• Meso-scale: polymer particle growth and morphology, fragmentation of catalyst, phase equilibria in the polymer particle, heat and mass transport in the particle.
• Macro-scale: Mass, heat, momentum and energy balances in the reactor, particle size distribution, residence time distribution, heat removal, polymer fouling, macro- and micro-mixing, non-uniform concentration and temperature fields in reactors.

Modeling of polymerization reactors is applied to:

• Simulations of non-standard modes of operation, e.g., reactor start-up.
• Training of process operators.
• Finding the optimum grade transition strategies.
• Estimation of kinetic parameters.
• Identification of reactor stability and optimization of reactor conditions.

Catalytic slurry tank reactors
There are four phases in the slurry tank reactor: the liquid, the gas, the amorphous polymer and the crystalline polymer phase. The processes taking place in this reactor are schematically shown on the Figure.

Loop reactors
The flow in the loop reactor schematically shown on Figure below is impelled by the axial pump. The main tubular system forms a closed loop. Effects of polymer fouling, viscosity of reaction mixture, polymer swelling, dynamics of catalyst activation and deactivation and supercritical mode of operation are investigated in our group.

Experimental studies of the growth of polymer particles
Polymerization micro-reactor capable of detailed studies of polymer particle growth and morphology is constructed in our research group. This micro-reactor is going to be unique in its capability to control polymerization conditions and to dynamically monitor the dynamics of particle growth by several independent measurements.

Modeling of polymer particle growth and morphology.

• Multi-site reaction kinetics. Catalyst activation and deactivation.
• Resistances to transport in the particle. Heat removal by vaporization of volatiles.
• Polymer swelling, crystallization and partial melting. Sorption equilibria in the particle.
• Particle morphology. Effect of morphology properties on the growth of the particle.
• Catalyst fragmentation and pore filling.
• Overheating and stability of polymer particles.
• Convective flow in the polymer particle.

Problems of the particle overheating, obtaining the high yield of polymer from catalyst and control of final particle morphology are relevant in current polymer industry.

Dynamics and Stability of Polymerization Processes.
Most polymerization processes are highly exothermic and reactor productivity is often constrained by heat transfer limitations and complex thermodynamic constraints. For example, slurry processes are restricted by swelling of amorphous polymer. Dynamic changes in catalyst activity (i.e., activation and deactivation) also affect the safe regions of operation. Systematic analysis of the stability of polymerization reactors is an actual problem due to the general trend of moving to shorter residence times and increasing the polymer production per hour. Advanced tools of the continuation and bifurcation analysis are used for the study of dynamics and stability of polymerization reactors.

Recent Publications

• Kosek J., Ray W.H.: Dynamics and Stability of Slurry Olefin Polymerization Processes , Recent Progres en Genie des Procedes 13(69), 97-104 (1999).
• Palmova I., Kosek J., Schongut J., Marek M., Stepanek K.: Oligomerization and Copolymerization of Dicyclopentadiene (DCPD), Recent Progres en Genie des Procedes 13(64), 199-206 (1999).

Industrial cooperations

• Chemopetrol Litvinov, Czech Republic
• Kaucuk Kralupy, Czech Republic

Last modified: 22-Nov-1999 Written By: jkk@vscht.cz (Juraj Kosek)

Contact persons: Juraj Kosek jkk@vscht.cz Milos Marek marek@vscht.cz