Loop slurry process, high-density polyethylene

Slurry-phase polymerization involves a solid from the beginning of the polymerization process. An important example is the production of high-density polyethylene (HOPE) using immobilized, solid Ziegler-Natta catalysts in a solvent (typically liquid alkanes). Slurry phase polymerization is carried out in stirred tank reactors or loop reactors where the three-phase system is pumped with high flow velodties to reduce the probability of reactor fouling (for details see Section 6.20). 

Linear polyethylenes are produced in solution, slurry, and increasingly, gas-phase low-pressure processes. The Phillips process developed during the mid 1950s used supported chromium trioxide catalysts in a continuous slurry process (or particle-form process) carried out in loop reactors. Earlier, Standard Oil of Indiana patented a process using a supported molybdenum oxide catalyst. The polyethylenes made by both these processes are HDPE with densities of 0.950-0.965 g/cm and they are linear with very few side-chain branches and have a high degree of crystallinity. 

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