Catalytic conversion of polyolefins into liquid fuels over MCM-41: Comparison with ZSM-5 and amorphous Si(O)2-Al2O3
Catalytic conversion of polyolefins into liquid fuels over MCM-41: Comparison with ZSM-5 and amorphous Si(O)2-Al2O3
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DOI：
10.1021/ef970055v
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发表时间：
1997-11-01
期刊：
影响因子：
5.3
通讯作者：
Escola, JM
中科院分区：
文献类型：
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作者：
Aguado, J;Sotelo, JL;Escola, JM
以新近发现的介孔硅酸铝MCM-41为催化剂，研究了低密度聚乙烯(LDPE)、高密度聚乙烯(HDPE)和聚丙烯(PP)的催化降解。并与ZSM-5沸石和无定形硅铝进行了比较。对于所有所研究的塑料，MCM-41被发现比无定形的SiO_2-Al_2O_3活性更高，这是由于前者存在较高的比表面积和均匀的介孔。与ZSM-5相比，MCM-41对线型和低支化聚合物(HDPE和LDPE)的降解活性较低，这可能与分子筛酸中心强度较高有关。然而，正如分子模拟测量所证实的那样，对于高取代度塑料，如PP，由于这些分子在进入沸石的窄孔时遇到了严重的空间位阻，所以这些分子的裂解情况正好相反。此外，对于LDPE、HDPE和PP的裂解，MCM-41对汽油和中间馏分油范围内的烃类的选择性明显高于ZSM-5。因此，MCM-41是一种潜在的将聚烯烃塑料废物转化为液体燃料的催化剂。
The catalytic degradation of both low-and high-density polyethylene (LDPE and HDPE) and polypropylene (PP) has been investigated using MCM-41, a mesoporous aluminosilicate recently discovered, as catalyst. The results obtained have been compared to those of ZSM-5 zeolite and amorphous silica-alumina. For all the studied plastics, MCM-41 has been found more active than the amorphous SiO2-Al2O3, asa consequence of the higher surface area and the uniform mesoporosity present in the former. Compared to ZSM-5, MCM-41 exhibits a lower activity for the degradation of linear and low branched polymers (HDPE and LDPE, respectively), which can be related to the higher strength of the zeolite acid sites. However, the opposite is observed for the cracking of highly substituted plastics such as PP due to the severe steric hindrances these molecules encounter to enter into the narrow pores of the zeolite, as confirmed by molecular simulation measurements. Moreover, for the cracking of LDPE, HDPE, and PP, the selectivities toward hydrocarbons in the range of gasolines and middle distillates obtained over MCM-41 are clearly higher than those of ZSM-5. Therefore, MCM-41 is a catalyst potentially interesting for the conversion of polyolefinic plastic wastes into liquid fuels.