Abstract Process Economics Program Report 19E BIMODAL LINEAR LOW-DENSITY POLYETHYLENE (November 1999) Poor processability of first-generation linear low-density polyethylene (LLDPE) has prevented full LLDPE penetration of high-pressure low-density polyethylene (LDPE) markets. In recent years, however, significant catalyst and process developments have improved the processability of PEs by making resins with broad bimodal molecular weight distributions. In 1994, Union Carbide developed a new LLDPE catalyst and has built a 660 million lb/yr (300,000 t/y) two-reactor cascade gas-phase plant to make bimodal LLDPE and high-density PE (HDPE). In 1995, Borealis introduced its new supercritical slurry PE technology, Borstar, which combines a loop reactor and a gas-phase reactor operating in series with a specialized proprietary catalyst to make bimodal high molecular weight HDPE and LLDPE. In 1996, Borealis employed the Borstar technology in a new 265 million lb/yr (120,000 t/yr) plant in Porvoo, Finland. Other polyolefins producers such as Quantum (now Equistar) and Mobil have also developed mixed metallocene/ziegler-natta catalyst systems that are claimed to produce LLDPE resins in a single reactor system with molecular weight distribution similar to those produced in a dual-reactor system. Bimodal LLDPE is targeted to compete with high-pressure LDPE and with bimodal HDPE in thin film applications. This Report reviews the process technologies for manufacturing bimodal LLDPE products and their production economics. We evaluate UNIPOL II technology, Borstar technology, and a mixed catalyst technology. In addition to the process evaluations, we present summaries of patents relating to the processes we evaluate, and of the current status of the bimodal LLDPE industry. Our estimates show that for the same capacity, a facility using Borstar technology will require higher capital investment than a plant using either UNIPOL II -type technology or a bimetallic catalyst system in one reactor. Bimodal LLDPE resins made in the UNIPOL II -type and Borstar facilities have similar net production costs, whereas resins made in plant using a metallocene/ziegler-natta catalyst system in a gas-phase reactor have the highest net production cost. PEP 94 19E NF
CONTENTS GLOSSARY... ix 1 INTRODUCTION...1-1 2 SUMMARY...2-1 INDUSTRY ASPECTS...2-1 TECHNICAL ASPECTS...2-2 Bimodal LLDPE by a UNIPOL II -Type Process...2-2 Bimodal LLDPE by a Borstar -Type Process...2-2 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System...2-3 Capital and Production Economics and Comparison of Technologies...2-3 3 PRODUCT REVIEW AND INDUSTRY STATUS...3-1 BACKGROUND...3-1 PRODUCT PROPERTIES...3-2 PRODUCERS...3-4 4 LLDPE BY A FLUIDIZED-BED GAS-PHASE PROCESS...4-1 BACKGROUND...4-1 PROCESS REVIEW...4-2 Bimodal Polymer Production...4-2 Catalysts...4-2 Process Improvements...4-3 DESIGN BASIS...4-3 PROCESS DESCRIPTION...4-3 Standard Grade LLDPE...4-3 Section 100 Catalyst Preparation...4-4 Section 200 Polymerization...4-4 Section 300 Vent Recovery...4-4 Section 400 Additive Addition...4-4 Section 500 Extrusion...4-5 Section 600 Bagging and Loading...4-5 Bimodal LLDPE...4-5 DESIGN BASIS AND ASSUMPTIONS...4-7 PROCESS DISCUSSION...4-16 Catalyst...4-16 Reaction...4-16 Materials of Construction...4-17 CAPITAL AND PRODUCTION COSTS...4-17 i
CONTENTS (Continued) 5 BIMODAL LLDPE BY THE SUPERCRITICAL SLURRY PROCESS...5-1 INTRODUCTION...5-1 PROCESS REVIEW...5-1 Reactor Conditions...5-2 Reactor Productivity...5-2 Product Range...5-3 Diluent Recovery...5-3 Catalysts...5-3 Process Improvements...5-4 DESIGN BASIS...5-4 PROCESS DESCRIPTION...5-4 Section 100 Polymerization...5-5 Section 200 Diluent Recovery...5-6 Section 300 Vent Recovery...5-6 Section 400 Polymer Finishing...5-6 PROCESS DISCUSSION...5-14 Catalyst...5-14 Prepolymerization...5-14 Reaction Conditions...5-14 Reactor Split/Gel Content...5-15 Product Range...5-16 PE Solubility in Suspension Diluent...5-16 Diluent Removal and Recovery...5-17 Storage and Shipping...5-17 Materials of Construction...5-17 CAPITAL AND PRODUCTION COSTS...5-18 iii
CONTENTS (Concluded) 6 BIMODAL LLDPE BY A MIXED METALLOCENE/ZIEGLER-NATTA CATALYST IN A SINGLE REACTOR...6-1 CATALYST TECHNOLOGY REVIEW...6-1 Metallocene Catalyst System...6-1 Bimetallic Catalyst System...6-2 Mobil Catalysts...6-3 Quantum Catalysts...6-4 Fina Catalysts...6-5 Exxon Chemical Catalysts...6-5 DESIGN BASIS...6-5 PROCESS DESCRIPTION...6-5 Section 100 Catalyst Preparation...6-6 Section 200 Polymerization...6-6 Section 300 Vent Recovery...6-6 Section 400 Additive Addition...6-7 Section 500 Extrusion...6-7 Section 600 Bagging and Loading...6-7 PROCESS DISCUSSION...6-14 Catalyst...6-14 Reaction...6-14 CAPITAL AND PRODUCTION COSTS...6-14 iv
FIGURES 3.1 Comparison of Molecular Weight Distributions...3-1 3.2 Comparison of Resin Extrudability...3-3 3.3 Comparison of Selected Properties for Film Applications...3-3 4.1 LLDPE via a Fluidized-Bed Process (UNIPOL Technology)... E-3 5.1 Bimodal LLDPE by Supercritical Slurry Process (Borstar Technoloy)... E-7 6.1 LLDPE via a Fluidized-Bed Process (Mixed Metallocene/Ziegler-Natta Technology)... E-11 v
TABLES 2.1 Summary of Capital and Production Costs for Bimodal LLDPE Processes...2-5 2.2 Comparison of Production Economics for Bimodal LLDPE Processes...2-6 3.1 Bimodal PE Players...3-5 4.1 Bimodal PE by Gas-Phase Process Patent Summary... A-3 4.2 Standard Grade LLDPE by UNIPOL Technology Design Basis and Assumptions...4-6 4.3 Bimodal LLDPE by UNIPOL Ii Technology...4-7 4.4 Standard Grade LLDPE by UNIPOL Technology Stream Flows...4-8 4.5 Bimodal LLDPE by UNIPOL Ii Technology Stream Flows...4-10 4.6 Standard and Bimodal LLDPE by UNIPOL Technology Major Equipment...4-12 4.7 Standard Grade LLDPE by UNIPOL Technology Utilities Summary...4-14 4.8 Bimodal LLDPE by UNIPOL Ii Technology Utilities Summary...4-15 4.9 Standard Grade or Bimodal LLDPE by UNIPOL Technology Total Capital Investment...4-18 4.10 Standard Grade or Bimodal LLDPE by UNIPOL Technology Capital Investment by Section...4-19 4.11 Standard Grade LLDPE by UNIPOL Technology Production Costs...4-21 4.12 Bimodal LLDPE by UNIPOL Ii Technology Production Costs...4-23 5.1 Bimodal PE by the Slurry Process Patent Summary... A- 5.2 Bimodal LLDPE by Borstar Technology Design Basis and Assumptions...5-7 5. 3 Bimodal LLDPE via Borstar Technology Stream Flows...5-9 5.4 Bimodal LLDPE by Borstar Technology Major Equipment...5-11 5.5 Bimodal LLDPE by Borstar Technology...5-13 5.6 Enhanced PE Made by Borstar Technology Capital and Production Costs...5-18 5.7 Bimodal LLDPE by Borstar Technology Total Capital Investment...5-20 TABLES (Concluded) vi
5.8 Bimodal LLDPE by Borstar Technology Capital Investment by Section...5-21 5.9 Bimodal LLDPE by Borstar Technology Production Costs...5-23 6.1 Bimodal PE by Mixed Catalyst Systems Patent Summary... A- 6.2 Bimodal LLDPE via Mixed Ziegler-Natta/Metallocene Catalyst System Design Basis and Assumptions...6-8 6.3 B imodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst Stream Flows...6-9 6.4 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System Major Equipment...6-11 6.5 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System...6-13 6.6 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System Total Capital Investment...6-16 6.7 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System Capital Investment by Section...6-17 6.8 Bimodal LLDPE via Mixed Metallocene/Ziegler-Natta Catalyst System Production Costs...6-19 vii