The Appryl PP process is a proprietary bulk-phase liquid polymerisation technology developed jointly by Elf Atochem (later TotalFinaElf / ATOFINA, now TotalEnergies/Arkema) and BP Chemicals (later BP Amoco). It is classified as a second-generation bulk polypropylene process, belonging to the same family as other liquid-phase CSTR-based technologies.
The technology was developed and operated exclusively by the Appryl joint venture. Following its dissolution into INEOS (via the 2024 TotalEnergies acquisition), the process know-how and intellectual property now reside within INEOS O&P.
Core Process — Bulk Liquid-Phase CSTR Polymerisation
The Appryl process polymerises propylene in liquid bulk phase — liquid propylene acts simultaneously as the monomer and the reaction medium, with no solvent or diluent required. Polymerisation is conducted at approximately 60–80°C and 30–40 atm pressure, sufficient to maintain propylene in the liquid state.
The central reactor is a large Continuous Stirred Tank Reactor (CSTR), described in published literature as the world's largest polypropylene reactor at the time of its commissioning around 1998, producing 250,000 t/yr from a single reactor. This is a distinguishing feature of the Appryl process — its scale-up of a single CSTR to extremely large volume, rather than using multiple loop reactors in series as in competing technologies.
The process is described as operating with a single residence time (ττ) maintained constant, producing a near-monodisperse residence time distribution characteristic of a well-mixed CSTR.
Catalyst System
The process uses a Ziegler-Natta catalyst system. The catalyst undergoes an activation pre-processing step before entering the reactor, which introduces a characteristic and measurable time delay (δδ) between catalyst injection and its activity in the reactor. This delay is a defining operational characteristic of the Appryl CSTR process and was the primary driver for the development of its advanced flatness-based controller.
Hydrogen is used as a chain transfer agent to control molecular weight (and therefore melt index) of the polymer, fed directly to the reactor without delay.
Deployments
Three plants have historically been built.
| Plant |
Location |
Capacity |
| PP1 |
Gonfreville-l'Orcher, France |
135–200 ktpa |
| PP2 |
Lavéra, France |
250 ktpa |
| PP3 |
Grangemouth, Scotland |
~250 ktpa |
Product Range
The original Appryl process is capable of producing homopolymers (HPP) and random copolymers (RCP). A proprietary block copolymerisation process was developed as the latest Appryl technology generation.
Distinguishing Characteristics vs. Competing Technologies
| Feature |
Appryl (CSTR Bulk) |
Spheripol (Loop Bulk) |
Unipol (Gas Phase) |
| Reactor type |
CSTR |
Loop reactor |
Fluidised bed |
| Phase |
Liquid bulk |
Liquid bulk |
Gas phase |
| Scale per reactor |
Very large (250 ktpa single) |
Moderate (series of loops) |
Moderate |
| Solvent |
None |
None |
None |
| Copolymer capability |
Yes (2nd stage) |
Yes (gas-phase GPR) |
Limited |
| Catalyst delay |
Significant (activation step) |
Moderate |
Low |
Deployments
Three plants have historically been built.
| Plant |
Location |
Capacity |
| PP1 |
Gonfreville-l'Orcher, France |
135–200 ktpa |
| PP2 |
Lavéra, France |
250 ktpa |
| PP3 |
Grangemouth, Scotland |
~250 ktpa |
References
- LôôkChem — Appryl Polypropylene- Home (archive)
- Petit N. et al.. Semantic Scholar — Control of an industrial polymerization reactor using flatness (Aug 1, 2002). Journal of Process Control 2002 (12), 559-565. DOI: 10.1016/S0959-1524(01)00049-X
- Naphthachimie — Subsidiary: APPRYL (accessed Jun 3, 2026)
