Monomer Recovery of Plastic Waste in a Fluidized Bed Process

Monomer Recovery of Plastic Waste in a Fluidized Bed Process 

Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstr. 45, 20146 Hamburg, Germany 

For the depolymerization of PMMA, molten metal bath, dry distillation, extruder processes and fiuidized-bed processes are used [19], The depolymerization reactor of a molten metal bath consists essentially of a gas- or oil-heated metal bath. The metals used are those which have a low melting point such as tin and lead. The PMMA regrind is fed from the storage silos onto the stirred metal bath. Bath temperature and a residence time of some minutes are important for good yield and quality of the MMA. 

In contrast to this, the residence time of the products in a fluidized bed lies between 1 and 5 s [20]. Buekens [21] studied the influence of the residence times in technical fluidized-bed processes. One of the main advantages in using a fluidized bed reactor for depolymerization is that it involves no contamination of organometallic compounds in the products and less environmental problems [1]. Therefore, companies are looking to use fluidized-bed processes especially for filled PMMA. The filler will contaminate the molten metal bath while in a fluidized bed the often expensive fillers can be recovered. 

Feedstock Recycling and Pyrolysis of Waste Plastics Converting Waste Plastics into Diesel and Other Fuels Edited by J. Scheirs and W. Kaminsky 2006 John Wiley Sons, Ltd ISBN 0-470-02152-7 

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