A solution-based route to LLDPE

Polyethylene (PE) is the world’s largest-volume commodity polymer. Along with high-density (HDPE) and low-density (LDPE) polyethylene, linear low-density polyethylene (LLDPE) is one of the three main types of PE. The global market for LLDPE is over 20 million metric tons per year, corresponding to about 30% of the total PE produced. In LLDPE production, three major types of low-pressure technologies are used: slurry, solution and gas-phase processes. FIGURE 1. Solution-phase LLDPE production process similar to Nova Chemicals’ SclairTech The process LLDPE is produced by copolymerization of ethylene with alpha-olefins using Ziegler-Natta catalysts. The most common co-monomers used in LLDPE production are 1-butene, 1-hexene and 1-octene. Figure 1 illustrates the process for butene-based LLDPE production via a solution technology similar to Nova Chemicals’ (Calgary, Alta.; www.novachem.com) solution-phase technology, known as SclairTech (Figure 2). The process shown is a swing process, which is also capable of producing different LLDPE and HDPE grades by utilizing other alpha-olefins as co-monomers. The process can be divided into four main operation areas: purification and catalyst preparation; reaction; distillation;…