stereochemistry and an investigation of statistical modeling they implicate site
epimerization or “back-skip” as the predominant contributor to the low stereospecificity of these metallocene catalysts. They claim that the indenyl’s 2-substituent
(the bridge-head position being position 1) in these catalyst systems helps to decrease
their tendency to undergo site epimerization [186].
6.5 Industrial Production of Syndiotactic Polypropylene
In 1993, just about 5 years after the initial discovery of the metallocene-based
syndiospecific catalyst systems and crystalline s-PP, the large scale commercial
production of s-PP was announced by Fina Oil & Chemicals, at the time a subsidiary
of Petrofina Belgium now itself an integrated part of the Total Petrochemical
company. To reach this stage, 5 years of intensive preparatory work was needed by
research groups and engineering teams from three companies: Fina Oil & Chemicals
USA, Fina Research/Petrofina Belgium, and Mitsui Toatsu Japan (Mitsui Chemicals
Inc). The preparations for the first industrial run with a supported metallocene
catalysts focused mainly on challenges that were expected to be encountered during
the following stages:
1. Pre-production phase: Large scale production, storage, and safe transportation of
the supported metallocene catalyst to the production site.
2. Production phase: Employment of the Phillips loop reactor technology for the
large-scale production of polypropylene with a supported metallocene catalyst
for the first time ever.
3. Post-production phase: The processing conditions (addition, extrusion, pelletization, etc.) and product handling.
The general efforts to meet these challenges are described in the rest of this
section, without the details and specifics that are given in the corresponding patents.
These measures are common to all supported metallocene catalysts in commercial
runs employing loop bulk or slurry processes.
Zr
Fig. 28 Generic structure of
syndiotactic-specific C 1
symmetric metallocene
reported by Waymouth [186]
96
A. Razavi
epimerization or “back-skip” as the predominant contributor to the low stereospecificity of these metallocene catalysts. They claim that the indenyl’s 2-substituent
(the bridge-head position being position 1) in these catalyst systems helps to decrease
their tendency to undergo site epimerization [186].
6.5 Industrial Production of Syndiotactic Polypropylene
In 1993, just about 5 years after the initial discovery of the metallocene-based
syndiospecific catalyst systems and crystalline s-PP, the large scale commercial
production of s-PP was announced by Fina Oil & Chemicals, at the time a subsidiary
of Petrofina Belgium now itself an integrated part of the Total Petrochemical
company. To reach this stage, 5 years of intensive preparatory work was needed by
research groups and engineering teams from three companies: Fina Oil & Chemicals
USA, Fina Research/Petrofina Belgium, and Mitsui Toatsu Japan (Mitsui Chemicals
Inc). The preparations for the first industrial run with a supported metallocene
catalysts focused mainly on challenges that were expected to be encountered during
the following stages:
1. Pre-production phase: Large scale production, storage, and safe transportation of
the supported metallocene catalyst to the production site.
2. Production phase: Employment of the Phillips loop reactor technology for the
large-scale production of polypropylene with a supported metallocene catalyst
for the first time ever.
3. Post-production phase: The processing conditions (addition, extrusion, pelletization, etc.) and product handling.
The general efforts to meet these challenges are described in the rest of this
section, without the details and specifics that are given in the corresponding patents.
These measures are common to all supported metallocene catalysts in commercial
runs employing loop bulk or slurry processes.
Zr
Fig. 28 Generic structure of
syndiotactic-specific C 1
symmetric metallocene
reported by Waymouth [186]
96
A. Razavi