High-density polyethylene: Production route
How two reactors in series make pipe that lasts decades
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.HDPE is made from ethylene at low pressure with solid catalysts. The main choices are slurry processes (loop reactors, or stirred tanks in cascade) and gas-phase fluidised beds, with Ziegler-Natta catalysts for most grades and chromium (Phillips) catalysts for blow moulding. Bimodal technology, two reactors in series, is the standard for high-value PE100 pipe and thin film. Many gas-phase plants are swing units that alternate between HDPE and LLDPE.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Slurry process, cascade stirred tanks (e.g. Hostalen ACP, Mitsui CX) | about 35-40% of HDPE capacity (indicative) | about 1.0 t ethylene, small butene, about 0.5-0.6 MWh power and steam for diluent recovery (indicative) | 300-500 kt/yr per line (indicative) | about 99% (indicative) | low-molecular-weight wax | ethylene cost plus about $100-150/t conversion (indicative) |
| Slurry loop process (e.g. CPChem MarTech, INEOS Innovene S) | about 30-35% (indicative) | about 1.0 t ethylene, about 0.4-0.5 MWh per t (indicative) | 400-1,000 kt/yr; CPChem's Golden Triangle site adds two 1 Mt/yr HDPE units from 2026 (Argus 2025) | about 99% (indicative) | minor | among the lowest conversion costs at large scale (indicative) |
| Gas-phase swing process (e.g. Unipol) | about 25-30% (indicative) | about 1.0 t ethylene, about 0.4 MWh per t (indicative) | 300-650 kt/yr (indicative) | about 99% (indicative) | vent gas recovered | lowest capex per tonne; flexible (indicative) |
| Bio-based HDPE | well under 1% (indicative) | about 1.7 t ethanol per t ethylene (ethylene tile) | Braskem Triunfo about 260 kt/yr bio-ethylene (indicative) | as fossil | water | about 30-50% premium (indicative) |
How each route works
Slurry process, cascade stirred tanks (e.g. Hostalen ACP, Mitsui CX)Ethylene is polymerised in a hexane diluent in two or three reactors in series with Ziegler-Natta catalyst and hydrogen to control molecular weight. Bimodal and trimodal grades for pipe and film are its strength.
Best for premium bimodal pipe and film; more energy for diluent handling.
indicative (industry standard) Slurry loop process (e.g. CPChem MarTech, INEOS Innovene S)Ethylene in an isobutane diluent circulates in a loop reactor with chromium or Ziegler-Natta catalyst. Chromium grades have broad molecular weight distribution suited to blow moulding.
Very large single lines and low cost; chromium resins dominate bottles and drums.
Argus Polyethylene Outlook, Sep 2025; indicative Gas-phase swing process (e.g. Unipol)Ethylene is polymerised in a fluidised bed without diluent; the same reactor can make LLDPE or HDPE by changing comonomer and catalyst.
Swing flexibility suits Indian and Gulf plants; bimodal options are more limited.
indicative Bio-based HDPESugarcane ethanol is dehydrated to ethylene and polymerised in standard plants (Braskem). Chemically identical to fossil HDPE and recyclable with it.
Drop-in, low carbon on a cradle-to-gate basis; limited supply.
ethylene tile (indicative) Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.