Abstract:

Converting waste plastics into usable energy or fuel can alleviate the problems caused by increasing plastic waste and decreasing fossil energy. An integrated pyrolysis and plasma-catalysis reforming system was proposed for hydrogen production from plastics. The product distribution from different plastics [e.g. high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS)] was explored under four different reforming modes (heating-alone, catalytic-alone, plasma-alone and plasma-catalysis). The experiments were carried out in a two-stage fixed-bed reactor embedded with a coaxial dielectric blocking discharge (DBD) plasma zone. Comparing heating-alone mode, plasma-alone and catalysis-alone reforming modes promoted hydrocarbon cracking and increased gas yields, especially for H₂. Plasma-catalysis reforming mode significantly increased the total gas and H₂ yields from three plastics, and H₂ selectivity of HDPE was the highest (66.44%). Characterisation of used catalysts revealed that the severity of catalyst sintering due to carbon deposition and pore blockage on the catalysts was in the following order: HDPE > PP > PS. The plasma discharge could improve the carbon deposition and metal phase aggregation problems on the catalyst surface, increase the specific surface area and pore volume of the catalysts, and reduce the average pore size. Therefore, the integrated pyrolysis and plasma-catalysis reforming system provided an effective reference solution for the optimization of energy production from plastic resources and supported the commercial application of the process.

Key words: plastics, plasma-catalysis, hydrogen production, catalysis, pyrolysis

摘要：

将废塑料转化为可用的能源或燃料，可以缓解塑料废弃物增加和化石能源减少带来的环境问题。为实现塑料高效热转化制备氢能，本文提出一种塑料热解耦合等离子体催化重整制氢的新路线。采用嵌有同轴介质阻挡放电（DBD）等离子体区的两段式固定床反应器，探索低温时高密度聚乙烯（HDPE）、聚丙烯（PP）和聚苯乙烯（PS）在单独加热、单独等离子体重整、单独催化重整和等离子体催化重整模式4种重整模式下的产物分布。结果表明：相较于单独加热模式，单独等离子体和单独催化重整模式均可提高气体产率，尤其是H₂；等离子体和催化剂具有协同作用，等离子体催化重整模式可大幅提高气体产率，其中高密度聚乙烯的H₂选择性最高（66.44%）；催化剂上的碳沉积和孔隙堵塞导致催化剂烧结严重程度顺序：HDPE>PP>PS。等离子体放电可以改善催化剂表面的碳沉积和金属相聚集问题，增加催化剂的比表面积和孔体积，减小平均孔径。因此，热解耦合等离子体催化重整系统为优化塑料能源生产提供了有效的参考方案。

关键词: 塑料, 等离子体催化, 制氢, 催化, 热解