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By Intratec Solutions
Polypropylene (PP) is a thermoplastic polymer formed by the polymerization of 10,000-20,000 monomers of propylene. With a global market of about 60 million metric tons per year, PP is the second most-used polymer globally.
More than 35% of the world's total PP is produced using LyondellBasell's (Houston; www. lyondellbasell.com) Spheripol technology.
The process
In Spheripol technology, polymerization is carried out in liquid propylene (a bulk-slurry process) in tubular loop reactors. This type of reactor has a high heat-removal capacity and avoids polymer deposition on reactor walls.
A polypropylene homopolymer production process via a bulk-slurry process similar to LyondellBasell Spheripol is depicted in the flowsheet (Figure 1). The process shown is capable of producing both homopolymer and random copolymer PP. For impact copolymer production, the addition of a gas-phase reactor is required. In this process, liquid propylene contacts a solid catalyst inside a loop reactor. The process can be separated into three main areas: purification and reaction; polymer degassing and pelletizing; and monomer recovery.
Reaction and purification. In this stage, fresh polymer grade (PG) propylene is sent to fixed-bed dryers for removal of...