CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Wei Feng,Mo Zheng,Jin Bai,Xianxian Zhang,Chuang Wu,Zhenxing Guo,Lingxue Kong,Zongqing Bai,Wen Li
Understanding the effects of co-pyrolysis synergies between low-rank coal and high-density polyethylene (HDPE) on the carbon structure evolution in char and the relationship between char structure and chemical bonds evolution is very needed. A combination of ReaxFF MD and experimental approaches provides an opportunity for fully understanding the dynamic profiles of char structures and coking trends during co-pyrolysis process of coal and HDPE. In this work, consistent conclusions were obtained from fixed-bed experiments and ReaxFF MD simulations in product distribution during both individual coal pyrolysis and co-pyrolysis at different temperatures. The ReaxFF MD simulation results reveal that adding HDPE partially inhibited the coking process of coal char. The RDF results indicated higher order degree and aromaticity exist in coal/HDPE(7:3)-Char when compared to those in coal-Char, which agrees well with the findings from XRD and FTIR approaches. By analyzing the evolution of C=C, C=O, C-O, C( sp 2 )-C( sp 3 ), C( sp 3 )-C( sp 3 ) and C( sp 2 )-H bonds in C 40 + fragments during secondary simulations of co-pyrolytic char, it was observed that the structural order and aromaticity of co-pyrolytic char increase with temperature, and the oxygen-containing bonds are the initial recombination sites for char formation. These findings provide rich theoretical information to complement the understanding of char structure in co-fed systems and the interaction between coal and HDPE blend.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
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.
研究领域:
能源与燃料化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CEMENT AND CONCRETE RESEARCH
·
2024
·
IF 10.9
Ya-Jun Wang,Xiao-Pei Zhang,Dong-Mei Liu,Jun-Guo Li,Jian-Bao Zhang,Yu-Wei Zhang,Ya-Nan Zeng,Yi-Tong Wang,Bao Liu,Xi Zhang,Ya-Jing Zhang
Ca 2 SiO 4 is the primary carbonation-reactive mineral in steel slag, and demonstrates significant carbon sequestration potential, yet its microscopic reaction processes remain unclear. This study investigated the carbonation behavior of Ca 2 SiO 4 using ReaxFF MD simulations. The results indicated that as CO 2 concentration increased, the capture rate of Ca 2 SiO 4 decreased, and the molecular structure of the resulting CaCO 3 varied in oxygen origin. At room temperature, the carbonation rate of Ca₂SiO₄ gradually decreased over time until it reached equilibrium. Increasing the temperature could reactivate the carbonation, but the rate would still decline until it reached equilibrium again. Higher temperatures could accelerate the formation of the intermediate C 2 O 5 2− and internal CO 3 2− diffusion, thereby boosting the carbonation and increasing CO 2 adsorption. This study investigated the carbonation of Ca 2 SiO 4 at the atomic level, aiming to link microscopic molecular processes with macroscopic experimental phenomena, thereby providing a theoretical foundation for enhancing the carbonation efficiency of steel slag.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2024
·
IF 5.8
Hongdi Yu,Fawei Lin,Xuan Guo,Chujun Luan,Eslam Salama,Mona Ossman,Xinghua Liu,Rundong Li,Jiantao Li,Lei Che,Wangyang Tian,Beibei Yan,Guanyi Chen
Pyrolysis of oily sludge (OS) possesses dual advantages of oil recovery and harmless treatment. Exploring the reaction pathway for petroleum hydrocarbons during pyrolysis in the presence of minerals is critical for optimizing pyrolysis parameters. This study selected six pure soil minerals and five typical oil compounds as representative to simulate OS samples. Model compounds are more helpful deriving and clarifying the internal mechanism. The mixed oil compounds were continuously loading fed into reactor loaded with varied minerals, which was facilitated the detection of pyrolytic products. Meanwhile, the pyrolysis reaction pathways of oil compounds at different temperature and pressure were simulated by ReaxFF MD. According to the experimental results, high temperature increased the content of light hydrocarbons and gas products (i.e., C 3 H 4 , C 4 H 8 , CH 4 , and H 2 ). Montmorillonite (MT) and illite (IT) exhibited catalytic ring-opening and cracking effects as alkaline minerals, while the kaolin (KL) presented catalytic aromatization effects. The catalytic ring-opening effect of calcite (CA) and hematite (MA) was equally evident, but quartz (QA) possessed a weak catalytic effect and even promoted condensation . n-Dodecane (ND) and 1-dodecene (1-DE) had more complicated pathways compared to other com-pounds with stable rings. The main cracking reaction pathway of ND was the breakage of β C C bond, and the C C bond at both ends was easier to break than the one in the middle. The pyrolysis reaction pathway of 1-DE not only included the breakage of β C C bond, and the generation of ethyl radicals. The methyl groups in methylcyclohexane (MC), methylbenzene (MB), and 1-methylnaphthalene (1-ME) could be detached, while ring-opening reactions generated free radicals . This work provides detailed explanation of pyrolysis reaction pathway of oil compounds and the catalytic mechanism of soil minerals, which helps us understand OS pyrolysis process.
研究领域:
环境化学
·
能源工程
·
石油污染治理
·
热解机理
·
计算化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）