Pressurized ex-situ catalytic co-pyrolysis of polyethylene and lignin: Efficient BTEX production and process mechanism analysis
Pressurized ex-situ catalytic co-pyrolysis of polyethylene and lignin: Efficient BTEX production and process mechanism analysis
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DOI：
10.1016/j.cej.2021.134122
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发表时间：
2021-12
影响因子：
15.1
通讯作者：
Linyao Ke;Yunpu Wang;Qiuhao Wu;Nan Zhou;Leilei Dai;Xiaojie Tian;Wanhao Huang;Yujie Peng;
中科院分区：
文献类型：
--
作者：
Linyao Ke;Yunpu Wang;Qiuhao Wu;Nan Zhou;Leilei Dai;Xiaojie Tian;Wanhao Huang;Yujie Peng;
塑料和生物质的异地催化共热解制芳烃已经得到了广泛的研究，同时也有报道称在压力下促进了芳烃化，但现有的研究并没有讨论催化共热解和压力对芳烃生产的综合影响。在Py-GC/MS系统中，研究了HZSM-5在一系列压力（0.1-0.8 MPa）下催化聚乙烯和木质素的非原位共热解。研究表明，在聚乙烯和木质素共热解过程中，加压操作可以在保持催化剂稳定性的同时大幅提高BTEX的相对产率。在温度650℃，压力0.5 MPa，聚乙烯与木质素比为1:1，催化剂与原料比为4:1的条件下，BTEX的相对产率可达70.94%。两种原料配比通过调控氢自由基发射和接收，显著影响氢自由基传质效率。聚乙烯与木质素的比例为4:3时，BTEX的相对收率最高为70.27%。在BTEX中，苯和甲苯由于位阻较低，更容易发生烷基化和缩聚成高支化和多环芳烃。氢自由基-传质对BTEX的生产有显著影响，传质效率可以通过适当的压力和原料配比来调节。同时，加压操作通过促进氢自由基传质和水的释放对阻焦具有双重积极作用，从而提高催化剂的稳定性和BTEX的产量。该研究为BTEX的高效生产提供了新的思路。
Ex-situ catalytic co-pyrolysis of plastic and biomass to aromatics has been extensively investigated, simultaneously, aromatization have been reported to be promoted under pressure, but available research did not discuss the combined effect of catalytic co-pyrolysis and pressure on aromatics production. In this work, ex-situ catalytic co-pyrolysis of polyethylene and lignin over HZSM-5 under a series of pressure (0.1–0.8 MPa) in a Py-GC/MS system was investigated. We show that pressurized operation during co-pyrolysis of polyethylene and lignin leads to a large increase in BTEX relative yield while maintaining catalyst stability. A very high BTEX relative yield of 70.94% can be achieved at temperature of 650 °C, pressure of 0.5 MPa, polyethylene to lignin ratio of 1:1, and catalyst to raw material ratio of 4:1. Ratio of two raw materials significantly affects efficiency of hydrogen radicals-mass transfer by regulation of hydrogen radical emission and reception. A peak value of BTEX relative yield of 70.27% was obtained at a polyethylene to lignin ratio of 4:3. Among BTEX, benzene and toluene are more prone to alkylate and polycondensate into highly branched and polycyclic aromatics, due to a lower steric hindrance. Hydrogen radicals-mass transfer has a significant effect on BTEX production, and mass transfer efficiency can be regulated by appropriate pressure and raw materials ratios. Meanwhile, pressurized operation has a dual positive effect on coke inhibition via promoting hydrogen radicals-mass transfer and water release, such that catalyst stability and BTEX production are promoted. This study offers new insight into efficient production of BTEX.