Clean Polymerisation Reactors: Elimination of fouling and coagulum in polymerisation reactors – CLEANPOLY

Coagulation of polymer colloids and, to a larger extent fouling, have been major problems for industry for years, but attracted relatively little academic attention. The CLEAN POLY project consortium has been set up to elucidate the underlying physico chemical causes of these phenomena in view of ultimately eliminating them. The overarching objective of the project is to:

Improve our understanding of how particles are stabilised, identify and quantify the mechanisms by which particles are destabilised to form either free-flowing coagulum or deposits on reactor walls to keep the reactors as clean, efficient and waste-free as possible.

This fundamental understanding will be used to propose protocols for process operation, process design and alternative formulations to reduce waste and increase process efficiency and product quality. These protocols will be tested both at the laboratory scale, and in commercial pilots. The context for this study is important: it is fundamental science that can be applied to any number of real-world situations. We will focus on 2 polymers here that are important to local industry: polyvinylidene fluoride (PVDF) will be the example polymer used for emulsion polymerisation (EP), and polyvinylchloride (PVC) will be the example for (micro)suspension polymerisation. Note that one model formulation per product will be chosen, however since both companies obviously produce multiple grades with different components and reaction conditions, the focus of the CLEAN POLY project will be on the fundamental understanding of issues that provoke fouling and coagulation (and how to control them) rather than on studying specific formulations or products.

Before beginning the experimental phase of the project however, the 2 PhD students involved in the CLEAN POLY consortium will use tools developed in a previous ANR project to perform computational fluid dynamic (CFD) simulations of representative reactor configurations and process equipment. This will allow us to design experiments that will be representative of the flow conditions (will clearly play a key role in the significance of fouling and coagulation) in real equipment, thereby allowing us to concentrate on commercially-pertinent conditions in the laboratory experiments carried out during the project. The experimental portion of project will be carried out in the form of 2 PhD projects, one dedicated to a very different model product; PVDF in emulsion polymerisation and PVC in a microsuspension process. Each polymer has different stabilisation mechanisms with the PhD responsible for PVDF formulations beginning with the development of an experimental programme for the study, characterisation, and elimination of coagulation. The other PhD will focus on PVC microsuspensions, and develop a similar programme for the elimination of fouling. Once the initial phase of the experiments has been completed, the students will switch focus, and use the experimental programmes of their colleague to study the mechanism they will not yet have considered. The desired outcome of this programme will be an understanding of the mechanisms of fouling and coagulation.

In collaboration with the PhD students, a postdoctoral fellow will develop a series of proposals for running cleaner polymerisation reactors, which be implemented on both lab scale, and pilot scale equipment in collaboration with the industrial partners.

It is expected that this project will have a significant, positive impact on the production processes of the two industrial partners, Arkema and Kemone, allowing them to reduce process waste, increase productivity, and eventually help speed new products through the development and scale-up phases.