Removal of organobromine compounds from the pyrolysis oils of flame retarded plastics using zeolite catalysts

Abstract

Two flame retarded plastics have been pyrolysed in the presence of two Zeolite catalysts to remove the organobromine compounds from the derived pyrolysis oil. The flame retarded plastics were, acrylonitrile -butadiene -styrene (ABS) that was flame retarded with tetrabromobisphenol A and high-impact-polystyrene (HIPS) that was flame retarded with decabromodiphenyl ether. The two catalysts investigated were Zeolite ZSM-5 and Y-Zeolite. Pyrolysis was carried out in a fixed bed reactor at a final pyrolysis temperature of 440 ºC. The pyrolysis gases were passed immediately to a fixed bed of the catalyst bed. It was found that the presence of Zeolite catalysts increased the amount of gaseous hydrocarbons produced during pyrolysis but decreased the amount of pyrolysis oil produced. In addition, significant quantities of coke were formed on the surface of the catalysts during pyrolysis. The Zeolite catalysts were found to reduce the formation of some valuable pyrolysis products such as styrene and cumene, but other products such as naphthalene were formed instead. The Zeolite catalysts, especially Y-Zeolite, were found to be very effective at removing volatile organobromine compounds. However, they were less effective at removing antimony bromide from the volatile pyrolysis products, although some antimony bromide was found on the surfaces of the spent catalysts.

Catalytic pyrolysis of waste plastic from electrical and electronic equipment

“…Pyrolysis has been suggested to be a promising processing path for the treatment of WEEE plastics, but generates an oil with a high content of bromine, derived from the brominated flame retardants added to the plastic [4][5][6]. Zeolite catalysts have been used to reduce the amount of bromine in the product pyrolysis oil [6,7].…”

“…Zeolite catalysts have been used to reduce the amount of bromine in the product pyrolysis oil [6,7]. Zeolite catalysts have also been used in the pyrolysis of other types of waste plastics, for example, municipal solid waste polyalkene plastics such as high density polyethylene and polypropylene to improve the quality of the product oils [8][9][10][11][12][13][14].…”

Transformation of tetrabromobisphenol A in the presence of different solvents and metals

“…It is known that PBDDs/Fs have toxicities similar to polychlorinated dibenzop-dioxins/dibenzofurans that are classified as carcinogenic compounds to human (Birnbaum et al, 2003). Moreover, pyrolysis oil could not be safely utilized as fuels or feedstocks if it contains a large amount of bromine (Hall and Williams, 2008). Therefore, separation of BFRs from both plastics and metal-rich fractions prior to thermal treatment is highly needed.…”

“…Destructive methods include catalytic decomposition and alkaline hydrothermal treatment for rapid degradation and decomposition of BFRs (Brebu et al, 2006;Hall and Williams, 2008). These destructive methods have several disadvantages.…”

“…For example, plastics may be degraded and could not be recovered. More importantly, corrosive compounds such as hydrobromic acid as well as toxic products such as bisphenol A likely formed during the destructive pretreatment may cause an even worse environmental problem and the associated containment and treatment of those products could be very costly (Brebu et al, 2006;Hall and Williams, 2008). Nondestructive methods involve in extraction of BFRs from WEEE using different solvents such as supercritical CO 2 and organic solvents (Altwaiq et al, 2003;Wang et al, 2004;Freegard et al, 2006).…”