Dai Leilei, Zhou Nan, Lv Yuancai, Cobb Kirk, Chen Paul, Wang Yunpu, Liu Yuhuan, Zou Rongge, Lei Hanwu, Mohamed Badr A, Ruan Roger, Cheng Yanling
Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN 55108, USA; State Key Laboratory of Food Science and Technology, Engineering Research Center for Biomass Conversion, Ministry of Education, Nanchang University, Nanchang 330047, China.
Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN 55108, USA.
Sci Total Environ. 2022 Nov 15;847:157658. doi: 10.1016/j.scitotenv.2022.157658. Epub 2022 Jul 28.
In this study, the microwave-assisted pyrolysis coupled with ex-situ catalytic reforming of polyethylene for naphtha range hydrocarbons, with low aromatic content, was investigated. Experimental results revealed that ZSM-5 zeolites with low SiO/AlO ratios led to high aromatic selectivity, while an extremely high SiO/AlO ratio significantly reduced the aromatic selectivity. The high selectivity of C5-C12 hydrocarbons (98.9 %) with low selectivity of C5-C12 aromatics (28.5 %) was obtained over a high silica ZSM-5 zeolite at a pyrolysis temperature of 500 °C, catalytic cracking temperature of 460 °C, and a weight hourly space velocity of 7 h. The liquid oil produced was mainly composed of C5-C12 olefins that can be easily converted into paraffin-rich naphtha by hydrogenation or hydrogen transfer reactions as the feedstock for new plastic manufacturing. 8 cycles of regeneration-reaction cycles were carried out successfully with little change on the product distribution, showing the great potential for continuous production of low-aromatic liquid oil. Catalyst characterization showed that the catalyst deactivation was primarily caused by coke deposition (approximately 16.0 wt%) on the surface of the catalysts, and oxidative regeneration was able to recover most of the pore structure and acidity of the zeolite by effectively removing coke. This study provides a better understanding for the plastic-to-naphtha process and even for scale-up studies.
在本研究中，对微波辅助热解与聚乙烯非原位催化重整制低芳烃含量石脑油范围烃类进行了研究。实验结果表明，低SiO/AlO比的ZSM-5沸石导致高芳烃选择性，而极高的SiO/AlO比显著降低芳烃选择性。在500℃的热解温度、460℃的催化裂化温度和7 h的重量时空速下，在高硅ZSM-5沸石上获得了C5-C12烃类的高选择性（98.9%）和C5-C12芳烃的低选择性（28.5%）。所产液体油主要由C5-C12烯烃组成，通过加氢或氢转移反应可轻松转化为富含石蜡的石脑油，作为新塑料制造的原料。成功进行了8个再生-反应循环，产物分布变化很小，显示出连续生产低芳烃液体油的巨大潜力。催化剂表征表明，催化剂失活主要是由催化剂表面的焦炭沉积（约16.0 wt%）引起的，氧化再生能够通过有效去除焦炭恢复沸石的大部分孔结构和酸度。本研究为塑料制石脑油工艺甚至放大研究提供了更好的理解。
