Reduction Behavior of Hematite Composite Containing Polyethylene and Graphite with Different Structures with Increasing Temperature
Reduction Behavior of Hematite Composite Containing Polyethylene and Graphite with Different Structures with Increasing Temperature
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DOI：
10.2355/isijinternational.49.809
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发表时间：
2009-06
影响因子：
1.8
通讯作者：
T. Murakami;Takumi Akiyama;E. Kasai
中科院分区：
文献类型：
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作者：
T. Murakami;Takumi Akiyama;E. Kasai
塑料废物可以通过提供还原气体，例如，H2和CO，通过热解。然而，存在塑料的热降解温度明显低于氧化铁的还原温度的问题。如果在复合颗粒内可以形成大的温差，则由此释放的还原气体可以用作还原剂。因此，本文研究了不同组成和结构的赤铁矿、石墨和聚乙烯复合材料的还原行为，以了解其还原行为，获得高的聚乙烯还原利用率。在惰性气体保护下进行了复合材料的还原实验，并对还原过程中生成的气体进行了连续分析。利用这些气体的浓度计算了赤铁矿的还原度。此外，微观和宏观结构的还原复合材料进行了观察。在碳氧比相同的条件下，聚乙烯的加入导致最终还原度降低。这表明聚乙烯对还原反应的贡献是有限的。这是因为裂纹的形成增强了复合材料的直接向外流动，而没有促进还原反应。相反，双层复合材料，其中聚乙烯的含量在内层中大于在外层中，显示出有效利用聚乙烯相比，均匀的复合材料。
Plastic wastes can play the significant role of reductants for iron oxides by supplying reducing gases, e.g., H2 and CO, through pyrolysis. However, there is a problem that the thermal degradation temperature of plastics is significantly lower than the reduction temperature of iron oxide. If a large temperature difference can be formed within the composite granule, the reducing gases thus released can be used as reductants. Therefore, in this paper, the reduction behavior of the composites prepared by using hematite, graphite, and polyethylene regents with different compositions and structures was examined in order to understand the reduction behavior and to attain a high utilized ratio of polyethylene to reduction. Reduction experiments of the composites were carried out under an inert gas flow, and gases formed during reduction were continuously analyzed. The reduction degree of hematite was calculated using the concentration of these gases. Further, micro- and macrostructures of the reduced composite were observed. The addition of polyethylene to a hematite composite containing polyethylene and graphite led to a decrease in the final reduction degree, under the same ratio of carbon to oxygen in the composite. This indicates that the contribution of polyethylene to the reduction reaction was limited. This is because the crack formation enhanced the direct outward flow of the composite without contributing to the reduction reaction. In contrast, the double-layer composite, in which the polyethylene content in the inner layer is larger than that in the outer, shows an effective utilization of polyethylene as compared to the homogeneous composite.