Halogen Derivatives in Pyrolyzed Plastics

Abstract

The article deals with the issue of waste plastics pyrolysis leading to the industrially applicable liquid and gaseous products. The problem of thermally labile halogenated compounds, present in the feedstock, is discussed. The introductory part focuses mainly on halogenated flame retardants and their toxicological and environmental risks. In comparison with the standard recycling of waste plastics, pyrolysis with subsequent material utilization of the liquid product is mentioned as a promising method capable to solve the problem with the presence of halogen derivatives. The following second part of the article summarizes studies searching suitable methods for removing inorganically and organically bound chlorine and bromine from pyrolysis organic condensates - i.e. pyrolysis oils. Dehalogenation processes are divided into several categories according to the nature of the process and also according to the method of application of the respective reagent, catalyst or sorbent. Within each group, the results published in the available literature are briefly summarized. When commenting on them, the main emphasis is placed on the applicability of the obtained pyrolysis oils as raw materials for refinery processing and new polymers production. At the end of the article, a plan of experiments is outlined, which will be carried out during the research of the issue by the authors team. The space is mainly dedicated to the construction of two laboratory apparatuses that has been developed for this purpose.The first batch apparatus working with a vertical retort allows studying of gaseous, liquid and solid pyrolysis products at various temperatures. The second, continuously operating apparatus, is designed to test the efficiency of hydrogen halides adsorption from gaseous mix-tures at high temperatures. The third apparatus designed for the research purposes is a catalytic continuous system enabling to study the decomposition of organic halogen derivatives. The results of the experiments will be published continuously after their verification with sufficient reproducibility.