Abstract
The development of waste treatment technologies for various types of waste from different sectors is inevitable. The technology should protect the environment, valuable resources and should be economical. Synthetic polymeric materials are one of the major portions of wastes in the developed and developing countries. Feedstock recycling process appears to be most promising among the various other methods. Dehalogenation process is a key technology in feedstock recycling mixed halogenated waste plastics. In this study, two different approaches have been made to clarify the effectiveness of our proposed catalytic dehalogenation process using various iron oxides and calcium carbonate as catalyst/sorbent. The first approach (two step process) is (i) thermal decomposition of waste plastics into oil, which contains various halogenated compounds and (ii) develop dehalogenation catalysts for the catalytic dehydrochlorination of organic chlorine compounds from mixed plastic-derived oil in a fixed bed reactor. The second approach (single step process) is the simultaneous degradation and dehalogenation of chlorinated (PVC) and brominated (high impact polystyrene with brominated flame retardant - HIPS-Br) mixed plastics to produce halogen free liquid products. We report a catalytic/sorptive process for the dehalogenation of chlorinated and brominated organic compounds formed in the pyrolysis of PVC and HIPS-Br mixed waste plastics i.e., PE, PP, and PS. During dehydrohalogenation, the iron and calcium based catalysts were transformed into their corresponding halides, which also showed high activity for the dehydrohalogenation of the organic halogenated compounds. The presence of small quantity of poly ethylene terephalate (PET) in municipal waste plastics and waste from electric and electronic equipment (WEEE) had significant effect on the formation of degradation products and dehalogenation process. The developed iron oxide and calcium carbonate carbon composites were effectively removed the halogen content with bifunctional (catalytic/sorptive) activities. The halogen free plastic derived oil (PDO) can be used as a fuel oil or feedstock in refinery.
