Hydrothermal liquefaction processes for plastics recycling: A review

Georgina C. Laredo , Joel Reza , Edith Meneses Ruiz
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引用次数: 13

Abstract

If our expectations are to have a future with the resources provided by the earth, the recycling of plastics has become one of the most important topics that, as humans, we must deal with. Among the technologies developed for treating this issue is the hydrothermal liquefaction (HTL) method. In this review, subcritical and supercritical hydrothermal processes are presented. Experimental methods and product yields are disclosed and discussed. Subcritical conditions have previously been used to depolymerize synthetic polymers containing heteroatoms, such as bisphenol-A-based epoxy resin (Epoxy), polyamide 6 (PA6), polyamide 6/6 (PA66), polyethylene terephthalate (PET), polycarbonate (PC), and polyurethane (PU). This type of polymer can be broken down using this low-temperature, low-pressure method because it has heteroatoms that are easy to break down. To depolymerize polyolefins like polyethylene (PE) and polypropylene (PP), derivatives and mixtures, formed by long hydrocarbon chains, supercritical water conditions (> 374 °C; > 23 MPa) seem to be required.  These requirements make the procedure quite expensive. The review showed that a new method that uses pressures between 2.5 and 30 MPa, temperatures above 400 °C, and residence times of 20 to 60 min, named low-pressure hydrothermal liquefaction (LP-HTL), can be used to handle this type of polyolefin hydrocarbon. This review describes the conditions needed to handle this problematic type of feedstock and, in a certain way, the possible utilization of such technology for treating more complex waste mixtures.

水热液化技术在塑料回收中的应用综述
如果我们的期望是利用地球提供的资源创造未来,那么塑料的回收利用已经成为作为人类必须处理的最重要的问题之一。为解决这一问题而开发的技术之一是水热液化(HTL)方法。本文介绍了亚临界和超临界水热过程。公开并讨论了实验方法和产物产率。亚临界条件先前已用于解聚含有杂原子的合成聚合物,例如双酚A基环氧树脂(环氧树脂)、聚酰胺6(PA6)、聚酰胺6/6(PA66)、聚对苯二甲酸乙二醇酯(PET)、聚碳酸酯(PC)和聚氨酯(PU)。这种类型的聚合物可以用这种低温、低压的方法分解,因为它有容易分解的杂原子。为了解聚聚乙烯(PE)和聚丙烯(PP)等由长烃链形成的聚烯烃、衍生物和混合物,似乎需要超临界水条件(>;374°C;>;23MPa)。这些要求使得该过程相当昂贵。综述表明,一种新的方法,即低压水热液化(LP-HTL),使用2.5至30 MPa的压力、400°C以上的温度和20至60分钟的停留时间,可以用于处理这种类型的聚烯烃烃。这篇综述描述了处理这种有问题的原料所需的条件,以及以某种方式利用这种技术处理更复杂的废物混合物的可能性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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