Degradation of polyethylene and polypropylene into fuel oil by using solid acid and non-acid catalysts
Degradation of polyethylene and polypropylene into fuel oil by using solid acid and non-acid catalysts
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DOI：
10.1016/s0165-2370(99)00013-3
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发表时间：
1999-07
影响因子：
6
通讯作者：
Y. Sakata;M. Uddin;A. Muto
中科院分区：
文献类型：
--
作者：
Y. Sakata;M. Uddin;A. Muto
通过间歇操作进行塑料聚合物、聚乙烯（PE）在430°C和聚丙烯（PP）在380°C下热降解和催化降解成燃料油。所用催化剂为酸催化剂硅铝（SA-1、SA-2）、ZSM-5沸石和非酸介孔氧化硅催化剂（硅质岩、介孔硅胶和介孔折叠氧化硅（FSM））。比较了催化降解与非催化热降解的产物气、液、残渣收率、液体产物回收率和沸点分布。本工作分为三个部分：（1）催化接触方式的影响研究;（2）催化剂类型对塑料降解的影响研究;（3）重复间歇操作降解PE和PP过程中催化剂的评价。对于在与SA-1液相接触中的PP降解，获得69 wt.%的液体烃产率，并且油的沸点（bp）在36 ° C和270°C之间，相当于正链烷烃n-C6至n-C15的bp。来自催化降解的液体产物具有与商业汽车汽油非常相似的碳数分布。对于汽相接触，液体产物的产率要低得多（54%），液体回收（或形成）速率也要慢得多。具有强酸中心的催化剂如ZSM-5沸石加速了PP和PE的降解，导致液体产率低。对于无酸中心的FSM，PP和PE降解成液体的初始速率与酸催化剂（SA-1）一样快，液体产率更高。FSM催化降解的液体产物具有类似于煤油和柴油的混合物的碳数分布。在重复使用时，SA-1由于催化剂上的焦炭沉积而非常迅速地失活，而FSM失活慢得多。这些发现有关FSM催化剂强烈表明，由二氧化硅片包围的介孔可以作为水库的自由基物种和自由基物种加速塑料熔体的降解。
The thermal and catalytic degradation of plastic polymers, polyethylene (PE) at 430°C and polypropylene (PP) at 380°C into fuel oil were carried out by batch operation. The catalysts employed were acid-catalysts silica–alumina (SA-1, SA-2), zeolite ZSM-5 and non acidic mesoporous silica catalysts (silicalite, mesoporous silica gel and mesoporous folded silica (FSM). The yields of product gas, liquid and residues; recovery rate of liquid products, and boiling point distribution of liquid products by catalytic degradation were compared with those of non-catalytic thermal degradation. The present work is divided into three sections: (1) a study of effect of catalytic contact mode and (2) a study of effect of types of catalysts on plastic degradation, and (3) the evaluation of catalysts during the degradation of PE and PP by repeating batch operation. For PP degradation in liquid phase contact with SA-1, the yield of liquid hydrocarbons was obtained with 69 wt.%, and the boiling point (bp) of the oil ranged between 36 and 270°C, equivalent to the bp of normal paraffins n-C6to n-C15. The liquid products from catalytic degradation have a carbon number distribution very similar to commercial automobile gasoline. For vapor phase contact, the yield of liquid products was much lower (54%) and the rate of liquid recovery (or formation) was much slower. Catalysts possessing strong acid sites such as zeolite ZSM-5 accelerated the degradation of PP and PE into gases which resulted in low liquid yields. For FSM, which possesses no acid sites, the initial rates of PP and PE degradation into liquid were as fast as that over an acid catalyst (SA-1) and the liquid yields were higher. The liquid products from catalytic degradation over FSM have a carbon number distribution similar to a mixture of kerosene and diesel oil. Upon repeated use SA-1 deactivated very rapidly due to coke deposition on the catalyst, whereas FSM deactivated much more slowly. These findings concerning the FSM catalyst strongly suggest that the mesopores surrounded by the silica sheet may act as reservoir for radical species and the radical species accelerate the degradation of plastic melt.