【作者】 陈源；

【导师】 陈烈强；

【作者基本信息】 华南理工大学 ， 化学工程， 2010， 博士

【摘要】 废旧电子电气产品中的阻燃塑料大多以填埋或焚烧的方式进行处理,这两种方式不仅浪费资源而且对环境造成极大污染。高温热解是将阻燃塑料油化的唯一途径,也是资源化回收利用废旧电子电气中阻燃塑料的有效途径之一。但由于溴代物阻燃剂的存在,给塑料热解油的应用前景提出挑战。虽然经过脱溴净化处理后的热解油经进一步分离可作为化工原料,但由于热解油组成体系的复杂性,使工艺流程极大地复杂化,因此热解油作为化工原料的应用前景受到严重限制。燃料油在我国的需求量极大,如果阻燃塑料热解油的性能指标可以达到燃料油的相应标准,可代替燃料油作为炉燃料使用,在节能与环保方面将具有现实意义。以含有十溴联苯醚为主要阻燃剂的废旧电视机外壳为研究对象,本论文选用两级真空无害化热解处理的技术路线,并采用纳米金属催化脱溴的技术方案对第二段热解油中的主要溴代物和含有溴代物的热解油进行脱溴净化处理。相关的技术和理论研究内容与结果如下:本文首先采用SEM,FTIR,GC/MS,TG/DTG等技术手段,研究了废旧电视机外壳的塑料类型,主要元素组成,阻燃剂类型,真空热解过程和热解动力学。建立了热解动力学模型。结果表明,电视机外壳塑料是典型的高抗冲聚苯乙烯(HIPS);所含阻燃剂是以十溴联苯醚为主,并含有少量八溴联苯醚和九溴联苯醚;样品在整个真空热解过程中经历两个快速失重阶段,且真空条件可显著降低其表观活化能。以管式炉为热解设备,采用真空热解方式,研究了瞬态热解条件和两级慢速升温条件下液态产物的组成分布和溴代物的分布规律。结果表明,两级真空热解方式显著影响液体产品中主要成分的产率以及溴代物的分布。五溴苯和低溴代联苯醚是第二段热解油中主要的溴代物。以1,2,4,5-四溴苯和十溴联苯醚为脱溴对象,负载型纳米金属Pd/C为催化剂,异丙醇为主要溶剂和氢源,借助GC/MS, HPLC和SEM等分析测试手段,研究了温度、催化剂用量、pH值、反应时间和外加烃类化合物等因素对脱溴效率的影响。建立了1,2,4,5-四溴苯脱溴的动力学模型,探讨了1,2,4,5-四溴苯和十溴联苯醚的脱溴机理。研究发现实验操作条件对脱溴效率产生显著影响。较高温度,较多催化剂用量,较长反应时间和氢氧化钠浓度为100mmol.L-1时更有利于Br的脱除。外加烃类化合物由于性质的差异,对脱溴效率的影响也不同,甲苯对脱溴效率产生强烈的抑制作用,而正己烷对脱溴效率几乎不产生影响。异丙醇最终脱氢转化为丙酮,1,2,4,5-四溴苯和十溴联苯醚经脱溴分别转化为苯和联苯醚。采用与溴代物脱溴相同的实验方案,对两级真空热解所得的第二段热解油进行了脱溴净化研究,并分析了净化处理后的热解油组成和溴代物分布。根据燃料油的行业标准SH/T0356-1996,对脱溴处理后的热解油的主要物化性能指标进行测定,结果表明热解油中的溴代物没有完全脱溴转化,但脱溴率达95.5%。经处理之后的热解油闪点约为25℃,运动粘度为5.6mm2.s-1,硫含量为0.0738%,与SH/T0356-1996中规定的相应指标相比,闪点较低,但运动粘度适中,硫含量远低于燃料油中硫含量的限定标准。更多还原

【Abstract】 The flame retarded plastics in waste electric and electronic equipments (WEEE) are usually disposed by landfill or incineration which not only wastes resource but also brings giant pollution on environment. Pyrolysis is the unique way to transform the plastics into oil, and is one of the effective approach to recycle plastics as well. However, because of the brominated flame retardants in WEEE plastics which raise a challenge of utilizing the oil with brominated compounds. Although the debrominated oil can be used as chemical feedstock after distillation, complexity of the oil hinders the development in industrialization. Fuel oil is in great need in China, if the physical and chemical properties of the treated pyrolysis oil can be up to the national standard of fuel oil ,and then can be used in industrial fields, that will have practical significance in energy saving and environmental protection.Taking the waste brominated flame retarded TV shells as research object, we select the technical route of two-step vacuum pyrolysis to degrade the brominated flame retarded WEEE, furthermore the nanotechnology is adopted to debrominate the main bromides in the oil collected from the second step. The related technical and theoretical studies are as follows: Several analytical techniques such as SEM, FTIR, GC/MS and TG/DTG were used to study the TV shells′physical and thermal properties. It has been found that TV shells are the typical high impact polystyrene(HIPS), and contain three polybrominated diphenyl ether(decabrominated diphenyl ether, nanobrominated diphenyl ether and octabrominated diphenyl ether in which decabrominated diphenyl ether is the major component ). As for the thermal property, the TV housings underwent two weight loss step, and the vacuum can significantly decrease the apparent activation energy.Pyrolysis experiments of TV housings under vacuum were carried out in a tube furnace. Influence of flash pyrolysis and two-step controlled pyrolysis on the products yield and distribution was studied. Experimental results showed, two-step controlled pyrolysis remarkably influence on the distribution and yield of main components and bromides. Pentabromobenzene and low bromine number polybrominated diphenyl ether are the main bromides.Taking 1,2,4,5-tetrabromobenzene (1,2,4,5-TBB) and decabrominated diphenyl ether as debrominated objects, nanoscaled Pd/C as catalyst, isopropyl alcohol as main solvent and hydrogen donor, meanwhile by means of GC/MS, HPLC and SEM, various factors which have effects on debromination were probed into. The debromination kinetics mode of 1,2,4,5-TBB was developed and the debromination mechanism was studied. The following conclusions could be drown: the reaction conditions remarkably influence the debromination efficiency. The high temperature, the more catalysts, the longer reaction time and temperate pH are benefit to debromination. Because of different properties, the additional hydrocarbons produce different influence on debromination rates and effects. The debromination rates are strongly suppressed in the presence of aromatic hydrocarbon such as toluene, but the debromination rates are hardly affected by the addition of aliphatic hydrocarbon such as n-hexane.Catalytic debromination and purification studies on pyrolysis oil of TV shells were carried out. The main components and bromides in the treated oil were analyzed, meanwhile the main physical and chemical properties were tested based on the standard of SH/T0356-1996. The results showed that the debromination efficiency was up to 95.5%. As for the oil quality, three indexes were obtained, flashpoint is about 25℃, kinematic viscosity is 5.6 mm2.s-1, sulfur content is 0.0738%. Comparing with the fuel oil, the flashpoint is lower, kinematic viscosity and sulfur content is both up to the standard of SH/T0356-1996.更多还原