Abstract Among the implemented strategies for recycling and reutilization of HDPE, pyrolysis process is considered an attractive alternative, because its potential to use waste materials to produce valuable chemical feedstock and high energy content hydrocarbons. Through pyrolysis transformation, plastics are thermally cracked in the absence of oxygen and the reaction parameters can be controlled to favor the production of specific compounds and liquid fractions. During this project, waste HDPE thermal decomposition was evaluated in a range of 450 to 550 °C, considering samples of 2 mm and 5 mm and a residence time of 30 min. A design of experiments was applied to find the optimal conditions to maximize the volatile fraction. Then the waste HDPE was transformed in a two-step pyrolysis in order to maximize the volatiles fraction and the intermediate and final products analyzed. According to results, A volatile fraction equivalent to the 97% of HDPE mass was obtained at 500 °C, with a 5 mm particle size and a hold time of 30 min. The chemical analysis of wax and oil products showed that, although both blends are similarly made of alkanes, alkenes, and dienes, the compounds found in oil are shorter-chain and in a greater variety than those found in wax.

中文翻译：

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用于废 HDPE 价值化的两步热解

摘要 在已实施的 HDPE 回收和再利用策略中，热解工艺被认为是一种有吸引力的替代方案，因为它具有利用废料生产有价值的化学原料和高能烃的潜力。通过热解转化，塑料在没有氧气的情况下进行热裂解，并且可以控制反应参数以有利于特定化合物和液体馏分的生产。在该项目中，考虑 2 mm 和 5 mm 的样品以及 30 分钟的停留时间，在 450 至 550 °C 的范围内评估了废 HDPE 热分解。应用实验设计来寻找使挥发性分数最大化的最佳条件。然后将废 HDPE 转化为两步热解，以最大限度地提高挥发物分数以及分析的中间产品和最终产品。根据结果​​，在 500 °C 下获得了相当于 HDPE 质量 97% 的挥发分，粒径为 5 mm，保持时间为 30 min。蜡和油产品的化学分析表明，虽然这两种混合物都由烷烃、烯烃和二烯组成，但油中发现的化合物比蜡中发现的化合物链短且种类更多。