Wei Feng,Mo Zheng,Lijun Jin,Jin Bai,Lingxue Kong,Huaizhu Li,Zongqing Bai,Wen Li
Co-pyrolysis of waste plastics and low-rank coal is a promising approach to deal with the serious waste crisis and improve the clean utilization of low-rank coal. In this work, the comprehensive co-pyrolysis behaviors of low-rank coal and polyethylene plastics were explored systematically by combining TG experiment, in-situ Py-TOF-MS technique, and ReaxFF MD simulation. The consistent results were obtained among three approaches to demonstrate the positive interaction exists between coal and PE during the co-pyrolysis process, which leads to volatile yield increasing with PE addition. TG experimental results showed that the blending ratio of 7:3 for coal and PE has the strongest synergy during the co-pyrolysis process, while Py-TOF-MS experimental results unraveled that the synergistic effect of coal and PE was determined by changing the content of pyrolysis products rather than by producing cross-reaction products. The PE addition significantly reduced the yield of MAHs and normal alkyl-substituted monophenols and increased the yield of olefins, alkanes, and aromatic derivatives. ReaxFF MD simulation results complement the experimental observation to obtain similar weight loss profiles with TG experiments and consistent identification of major representative tar pyrolyzates with Py-TOF-MS experiments. Particularly, the detailed gas evolving trends and the underlying bond-breaking reactions of C C, C O, and C H bonds were revealed by ReaxFF MD, which indicates PE addition promotes bond breaking of C C and C H to enhance more tar generation. The combination of experiments and ReaxFF MD simulations can capture the comprehension of the co-pyrolysis process between low-rank coal and PE, which can be extended to other co-pyrolysis applications for related solid fuels.
Wei Feng,Xiaodong Chen,Jin Bai,Mo Zheng,Jinjun Guo,Congbin Jiang,Xianxian Zhang,Zongqing Bai,Wen Li
Integrating ReaxFF MD with TGA and in-situ Py-TOF-MS reveals synergistic mechanisms in co-pyrolysis of coal with HDPE, PP, and PS. • PP promotes C 5 -C 6 high-calorific gases, while PS enhances aromatics by cross-linking pathways. • PP promotes C C and C H cleavage while PS inhibits C O breaking and weakly promotes C H cleavage. • Coal/HDPE and coal/PP co-pyrolysis drive PAHs formation via Diels-Alder, alkylation, and aromatization reactions. • The polymer type critically determines the nature of the dominant reactive intermediates. Co -pyrolysis of low-rank coal and waste polymers offers a promising approach for plastic valorization while enhancing coal utilization and oil quality. In this work, the polymer types on the synergistic mechanism governing the co -pyrolysis of Zhundong low-rank coal and three typical polymers of HDPE, PP and PS were systematically investigated by integrating ReaxFF MD simulation with experiments of TG and in-situ Py-TOF-MS. It is observed that the temperatures of maximum weight loss ( T max ) follow the order of HDPE > PP > PS, consistently reproduced across three methods. PP addition promotes C 5 -C 6 high-caloric-value gases via long-chain cleavage while inhibiting the MAHs production. In contrast, PS facilitates phenolic hydroxyl removal from coal, promoting aromatic products. PS preferentially enhances light tar yield from 17.81% to 22.14%, whereas HDPE suppresses heavy tar yields from 39.90% to 35.56%. The ReaxFF MD simulation results further demonstrate the underlying molecular-scale mechanisms that are hardly accessible by experiments. HDPE and PP inhibit C O bond formation while promoting C H bond breaking during the co-pyrolysis. PP exhibits the strongest promotion of C-C/ C H cleavage, whereas PS shows the weakest effect on C H dissociation. During coal/HDPE and coal/PP co-pyrolysis, the formation of PAHs is promoted through Diels-Alder, alkylation and aromatization reactions. For coal/PS, the phenyl-alkyl radicals from PS combine with light tar, heavy tar, and char intermediates from coal to form cross-linked intermediates, facilitating cleavage of α -C ar -C al , β -C al -C al , and C ar -O bonds toward aromatics. The integrated strategy provides a comprehensive perspective for understanding co-pyrolysis mechanisms in other solid fuels and waste treatments. Download: Download high-res image (87KB) Download: Download full-size image
危险品化学品经营许可证（带存储）