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

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

Analysis of products from the pyrolysis of plastics recovered from the commercial scale recycling of waste electrical and electronic equipment

Three plastic fractions from a commercial waste electrical and electronic equipment (WEEE) processing plant were collected and investigated for the possibility of recycling them by batch pyrolysis. The first plastic was from equipment containing cathode ray tubes (CRTs), the second plastic was from refrigeration equipment, and the third plastic was from mixed WEEE. Initially, the decomposition of each of the plastics was investigated using a TGA linked to a FT-ir spectrometer which showed that the CRT plastic decomposed to form aliphatic and aromatic compounds, the refrigerator plastic decomposed to form aldehydes, CO2, aromatic, and aliphatic compounds, and the mixed WEEE plastic decomposed to form aromatic and aliphatic compounds, CO2, and CO. Each plastic mixture was also pyrolysed in a batch reactor to determine the halogen and metal content of the pyrolysis products, additionally, characterisation of the pyrolysis oils was carried out by GC-MS and the pyrolysis gases by GC-FID and GC-TCD. It was found that the halogen content of the oils was relatively low but the halogen and metal content of the chars was high. The pyrolysis oils were found to contain valuable chemical products and the pyrolysis gases were mainly halogen free, making them suitable as a fuel

Processing waste printed circuit boards for material recovery

PURPOSE We have investigated the use of pyrolysis for the processing of waste printed circuit boards (PCBs). The aim was to make the process of separating the organic, metallic, and glass fibre fractions of PCBs much easier and therefore make recycling of each PCB fraction more viable. DESIGN / METHODOLOGY / APPROACH The PCBs were pyrolysed in a fixed bed reactor at 850°C. The organic fraction released by the boards was analysed by a variety of gas chromatography techniques. The residue that remained after pyrolysis was analysed by ICP-MS to determine the type of metals that were present. FINDINGS When PCBs were heated to 800°C in an oxygen free atmosphere, the organic fraction decomposed to form volatile oils and gases leaving behind the metal and glass fibre fraction of the boards. The pyrolysed boards were very friable and the different fractions (metal components, copper power boards, glass fibre, etc) could be easily separated. The recovered metals could then be recycled by traditional routes with particular emphasis being placed on the recovery and recycling of rare and precious metals. The organic oils and gases which are produced during pyrolysis of PCBs can either be used as a chemical feedstock or as a fuel. RESEARCH LIMITATIONS/IMPLICATIONS The research was only carried out on a very small scale so an investigation into scale-up must be performed. PRACTICAL IMPLICATIONS By using pyrolysis, the organic and metallic fraction of printed circuit boards can be separated and recycled. ORIGINALITY/VALUE This paper presents a novel method for resource recovery from PCBs

Quantification of polybrominated diphenylethers in oil produced by pyrolysis of flame retarded plastic

In recent years, there has been extensive research into using pyrolysis to convert toxic brominated plastics into safe, bromine free fuels. However, there has been little investigation of the polybrominated diphenyl ethers (PBDE) that are present in the pyrolysis oils. PBDEs are brominated flame retardants that are extremely toxic and are difficult to analyse owing to the existence of 209 different congeners. In this work, the authors have investigated the PBDEs present in the pyrolysis oil of high impact polystyrene which contained decabromodiphenyl ether as a flame retardant. The plastic was pyrolysed in a fluidised bed reactor and the resulting oil was subjected to a rigorous clean-up procedure to remove interfering compounds before the PBDEs were quantified using gas chromatography–mass spectrometry. It was found that the most prominent PBDEs in the oil were 3-monoBDE, 4-monoBDE, 3,49-diBDE, 3,39,4-triBDE and 2,29,4,49,5,69-hexaBDE. The lesser brominated PBDEs were more prevalent than the more heavily brominated PBDEs

Pyrolysis of latex gloves in the presence of y-zeolite

In this study we have investigated the possibility of processing waste rubber gloves using pyrolysis. Y-zeolite catalyst was employed to upgrade the pyrolysis products to give higher yields of valuable aromatic compounds such as toluene and xylenes. The composition of the pyrolysis products was determined using GC-MS, GC-FID, GC-TCD, and FT-IR. It was found that when rubber gloves were pyrolysed in the absence of a catalyst, the pyrolysis oil consisted mainly of limonene and oligomers of polyisoprene. When Y-zeolite was added to the reaction system, the yields of toluene, xylene, methylbenzenes, ethylbenzenes, and naphthalenes increased dramatically. The Y-zeolite also catalysed the decomposition of limonene, which was absent from the catalytic pyrolysis products. The presence of the Yzeolite catalyst also increased the yield of hydrocarbon gases. The tests were carried out at both 380°C and 480°C and it was found that the higher reaction temperature led to increased yields of all the major compounds, both in the presence and absence of the Y-zeolite catalyst

The evaluation of waste tyre pulverised fuel for NOx reduction by reburning

The combustion of coal for power generation will continue to play a major role in the future, however, this must be achieved using cleaner technologies than we use at present. Scrap tyre arisings in the UK are 400,000 tonnes per year amounting to 30 million tyres and in the EU as a whole, more than 2.5 million tonnes of tyres per year are scrapped. The recent EC Waste Landfill Directive (1999) sets a deadline for the banning of whole and shredded tyres from landfill sites by 2006. Consequently, there is an urgent need to find a mass disposal route for tyres. We describe, in this paper, a novel use for tyre rubber pulverised fuel in a NOx reburning process which may have an application in power station boilers. This method of disposal could represent a way of combining waste disposal, energy recovery and pollution control within one process. A preliminary study of micronised tyre combustion was undertaken to identify the suitable size ranges for application in NOx reduction by reburning. Tests were performed in a down-fired, pulverised fuel combustor (PFC) operating at about 80 kW. Superior combustion characteristics, i.e. burnout were achieved with particle sizes less than 250 μm. A South African coal was used as the primary fuel in the reburn tests and the tyre was fed pneumatically via a separate feed system. Parameters studied, were, reburn zone stoichiometry and reburn fuel fraction. Additionally, the carbon content of the ash was carefully monitored for any effect on burnout at the fuel rich reburn stoichiometries. The NOx reductions achieved with tyres are compared with reburning with coal. NOx reductions up to 80% were achieved with tyres at half of the reburn fuel feed rate required to achieve the same reductions by coal. The results have been evaluated within the context of other studies available in the literature on NOx reburning by bituminous coal, brown coal, gas and biomass

The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

The co-pyrolysis of brominated high impact polystyrene (Br-HIPS) with polyolefins using a fixed bed reactor has been investigated, in particular, the effect that different types brominated aryl compounds and antimony trioxide have on the pyrolysis products. The pyrolysis products were analysed using FT-IR, GC-FID, GC-MS, and GC-ECD. Liquid chromatography was used to separate the oils/waxes so that a more detailed analysis of the aliphatic, aromatic, and polar fractions could be carried out. It was found that interaction occurs between Br-HIPS and polyolefins during co-pyrolysis and that the presence of antimony trioxide influences the pyrolysis mass balance. Analysis of the Br-HIPS + polyolefin co-pyrolysis products showed that the presence of polyolefins led to an increase in the concentration of alkyl and vinyl mono-substituted benzene rings in the pyrolysis oil/wax resulting from Br-HIPS pyrolysis. The presence of Br-HIPS also had an impact on the oil/wax products of polyolefin pyrolysis, particularly on the polyethylene oil/wax composition which converted from being a mixture of 1-alkenes and n-alkanes to mostly n-alkanes. Antimony trioxide had very little impact on the polyolefin wax/oil composition but it did suppress the formation of styrene and alpha-methyl styrene and increase the formation of ethylbenzene and cumene during the pyrolysis of the Br-HIPS

Analysis of CO₂ leakage through "low-permeability" faults from natural reservoirs in the Colorado Plateau, southern Utah

The numerous CO2 reservoirs in the Colorado Plateau region of the United States are natural analogues for potential geologic CO2 sequestration repositories. To better understand the risk of leakage from reservoirs used for long-term underground CO2 storage, we examine evidence for CO2 migration along two normal faults from a reservoir in east-central Utah. CO2 -charged springs, geysers, and a hydrocarbon seep are localised along these faults. These include natural springs that have been active for long periods of time, and springs that were induced by recent drilling. The CO2 -charged spring waters have deposited travertine mounds and carbonate veins. The faults cut siltstones, shales, and sandstones and the fault rocks are fine-grained, clay-rich gouge, generally thought to be barriers to fluid flow. The geologic and geochemical data are consistent with these faults being conduits for CO2 to the surface. Consequently, the injection of CO2 into faulted geologic reservoirs, including faults with clay gouge, must be carefully designed and monitored to avoid slow seepage or fast rupture to the biosphere

Catalytic Biochar and Refuse-Derived Char for the Steam Reforming of Waste Plastics Pyrolysis Volatiles for Hydrogen-Rich Syngas

High-density polyethylene (HDPE) was pyrolyzed in a fixed-bed reactor and the derived pyrolysis volatiles passed directly to a second-stage fixed-bed reactor for catalytic steam reforming with the aim to produce hydrogen-rich syngas. The catalysts used were biochar produced from the pyrolysis of waste biomass and solid waste char produced from the pyrolysis of processed municipal solid waste in the form of refuse-derived fuel (RDF). The influence of char catalyst temperature and steam input were used to optimize the production of H2 syngas. Other types of waste plastics (low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and poly(ethylene terephthalate) (PET)) were also investigated to compare with the production from HDPE. The highest yields of syngas (H2, CO) were produced at 3.83 g gplastic-1 for biochar as the catalyst and 2.73 g gplastic-1 for RDF char as the catalyst, when the steam input was 10 g h-1 gcatalyst-1 and catalyst temperature was 1000 °C. Increasing amounts of steam input also increased the syngas yield, but at high steam inputs, saturation of the catalyst reduced syngas yield. Of the different plastic types investigated, the polyolefin plastics (HDPE, LDPE, PP) produced the highest yield of syngas, whereas PS and PET yields were significantly lower in the presence of both biochar and RDF char catalysts. Hydrogen yields were ∼0.44 g gplastic-1 for the polyalkene plastics with the biochar catalyst but were only ∼0.32 g gplastic-1 with the RDF char catalyst. At 1000 °C, the H2 potential from the processing of plastic with RDF char as the catalyst was higher than with biochar as the catalyst, which was attributed to the higher presence of an inorganic metal in the RDF char possessing catalytic properties

Thermal-hydraulic studies of the Advanced Neutron Source cold source

The Advanced Neutron Source (ANS), in its conceptual design phase at Oak Ridge National Laboratory, was to be a user-oriented neutron research facility producing the most intense steady-state flux of thermal and cold neutrons in the world. Among its many scientific applications, the production of cold neutrons was a significant research mission for the ANS. The cold neutrons come from two independent cold sources positioned near the reactor core. Contained by an aluminum alloy vessel, each cold source is a 410-mm-diam sphere of liquid deuterium that functions both as a neutron moderator and a cryogenic coolant. With nuclear heating of the containment vessel and internal baffling, steady-state operation requires close control of the liquid deuterium flow near the vessel`s inner surface. Preliminary thermal-hydraulic analyses supporting the cold source design were performed with heat conduction simulations of the vessel walls and multidimensional computational fluid dynamics simulations of the liquid deuterium flow and heat transfer. This report presents the starting phase of a challenging program and describes the cold source conceptual design, the thermal-hydraulic feasibility studies of the containment vessel, and the future computational and experimental studies that were planned to verify the final design