A Comparison of the Influence of Temperature During Slurry and Gas Phase Propylene Polymerization on Ziegler‐Natta Catalyst

Abstract

Summary Semi‐batch propylene polymerizations were performed in slurry and gas phase using a supported Ziegler‐Natta catalyst. The obtained instantaneous reaction rates were fitted with a kinetic model, and the influence of bulk temperature and reaction phase on kinetic parameters was studied. The estimated propagation constant increased with increasing reaction temperature up to 90 °C in slurry phase polymerizations, but reached a maximum at 60 °C when propylene was polymerized in the gas phase. Gas phase stopped flow reactions were done at 60 and 70 °C to investigate the strong influence of temperature during the initial instants of reaction and to evidence thermal degradation at particle level. These results and those from autoclave reactor were well consistent and could explain the effects of temperature.

The Effect of Reactor Conditions on High‐Impact Polypropylene Properties and Gas Phase Polymerization Kinetics

“…This can be done by changing the precatalyst (as shown by Smolná et al), or, if the same precatalyst is maintained, modifying its preparation and injection, as well as the phase in which the polymerization is carried out. The homopolymerization step can show different activities and lead to different morphologies depending on these factors, as shown in previous publications . In the current work, different precontact procedures between precatalyst, alkyl aluminium, and external lewis base were used to obtain different iPP morphologies, as shown by Cancelas et al Keeping constant copolymerization conditions and ethylene/propylene ratio, the influence of iPP morphology on the EPC distribution was studied.…”

“…Then, reaction rate was fitted to the kinetic model with lumped rate constants and 1st order deactivation shown in refs. and . The amount of homopolymer for each powder was estimated with the kinetics during reaction.…”

Systematic Comparison of Slurry and Gas‐Phase Polymerization of Ethylene: Part I Thermodynamic Effects

“…Therefore, the same catalyst might experience a different fragmentation process and morphology evolution in slurry and gas‐phase reactors. [ 19 ] In this paper, we will not discuss this point any further, as it has already been extensively studied elsewhere. [ 21–23 ]…”

“…Laboratory-scale polymerizations are mostly conducted in semi-batch slurry reactors, because they are easier to operate than gas-phase reactors, it is simple to design the reactor system and agitator, and the diluent helps control reactor temperature and particle overheating. [8][9][10][11][12][13][14][15][16][17][18][19] Nevertheless, one needs to avoid undesired phenomena that may affect the measured polymerization kinetics such as catalyst leaching-particularly important for supported metallocene catalysts-dissolution of polymer chains with low molecular weight and/or high comonomer content, and reactor fouling. [20] In bench-scale stirred-bed gas-phase reactors, on the other hand, one needs to deal with different types of technical issues to generate reliable results.…”

“…[20] In bench-scale stirred-bed gas-phase reactors, on the other hand, one needs to deal with different types of technical issues to generate reliable results. [8][9][10][11][12][13][14][15][16][17][18][19] In this case, an inert seedbed-NaCl or polymer powder-is needed to disperse the supported catalyst particles and to prevent them from sticking to each other and to the reactor walls. Seedbed materials have high surface areas and can adsorb impurities.…”