Polyethylene recycling technologies

Air Products and Chemicals, Inc. has been selected to supply a hydrocarbon and nitrogen recovery system for a new polyethylene manufacturing plant in Baytown, TX. The plant will be owned by Chevron Phillips Chemical Company and Solvay Polymers, Inc. The recovery system uses partial condensation in conjunction with Air Products pressure swing adsorption technology to recover hydrocarbons in the polyolefin plants, and recycle nitrogen with a purity of greater than 99%55. 

The Air Products technology will be able to recover almost 100% of the hydrocarbon off-gas from the slurry phase polyethylene process and more than 97% of the high-purity nitrogen that is used in degassing. Both of these gas streams will be recycled and re-used to reduce the VOC and NOx environmental emissions that are typically associated with flaring or burning plant off-gasses55. 

DuPont offers a family of biodegradable polymers based on polyethylene terephthalate (PET) technology known commercially as Biomax. Proprietary monomers are incorporated into the polymer, creating sites that are susceptible to hydrolysis. At elevated temperatures, the large polymer molecules are cleaved by moisture into smaller molecules, which are then consumed by naturally occurring microbes and converted to carbon dioxide, water and biomass. Biomax can be recycled, incinerated or landfilled, but is designed specifically for disposal by composting. 

F. L. BAYER, Polyethylene terephthalate (PET) recycling for food contact applications Testing, safety and technologies - A global perspective, Food Additives and Contaminants, 2002, 19(Supplement), 111-134. 

J. G. Poulakis and C.D. Papaspyrides, The Dissolution/Reprecipitation Technique Applied on High-Density Polyethylene I. Model Recycling Experiments, Advances in Pol)uner Technology, 14, 3, pp. 237-242 (1995). 

Eid, A., Mikitaev, M. A., Bedanokov, A. Y, and Mikitaev, A. K. Recycled Polyethylene Terephthalate/Organo-Montmorillanite Nanocomposites, Formation and Properties. The first Afro-Asian Conference on Advanced Materials Science and Technology (AMSAX 06), Egypt (2006). 

Ahn WS, Park SJ, Lee SY (2001) Production of poly(3-hydroxybutyrate) from whey by cell recycle fed-batch culture of recombinant Escherichia coli. Biotechnol Lett 23 235-240 Alias Z, Tan IKP (2005) Isolation of palm oil-utilising, polyhydroxyalkanoate (PHA)-producing bacteria by an enrichment technique. Bioresource Technology 96(11) 1229-1234 Alvarez HM, Kalscheuer R, Steinbuchel A (1997) Accumulation of storage lipids in species of Rhodococcus and Nocardia and effect of inhibitors and polyethylene glycol. Fett/Lipid 99 239-246... 

Bayer F. Polyethylene terephthalate recycling for food-contact apphcations testing, safety and technologies a global perspective. Food AdditContam 2002 19 (supplement) 111-134. 

The difficulty of sorting plastic resins It is technically difficult to obtain relatively pure resins ffom mixed plastics collected for recycling. Commercially demonstrated separation technologies are almost exclusively limited to processes that separate polyethylene terephthalate (PET) and high density polyethylene (HOPE). 

---