CHEMICAL ENGINEERING JOURNAL
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2023
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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
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Qingqi Zheng,Dequan Zhang,Peng Fu,Aixia Wang,Yongmei Sun,Zhiyu Li,Qingwen Fan
Unraveling the role of volatile evolving and char structural evolution, as well as the pyrolysis reaction pathway, is crucial for lignin effective valorization by a pyrolysis-based biorefinery approach. The fast pyrolysis of lignin at 200–800 °C was conducted to explore volatile release characteristics and their link with char structure evolution. The release of simple substituted aryl compounds below 350 °C was aided by the cleavage of β-O-4 and α-O-4. The C-O, C–C, and carboxyl groups of the depolymerized free radical fragments were cleaved further, providing stable mono-phenol (350 °C → 500 °C). Secondary reactions and pyrolytic macromolecular compounds resulted in the synthesis of polycyclic aromatic hydrocarbons (>700 °C). A cubic polynomial was developed to correlate the aromaticity with the atom ratio of H/C. The ring condensation degree and H/C demonstrated an excellent positive linear correlation. Additionally, the aromatization started at 350 °C, and small aromatic rings were changed into more ordered rings (≥6 rings). The fused-ring structures of char had progressed in the following order: 1 × 2, 2 × 3, 4 × 4, and 4 × 5, corresponding to 350 °C, 500 °C, 600 °C, and 800 °C, respectively. High temperatures contributed to the formation of aromatic monomers. Lignin pyrolysis pathway was established based on the correlation between volatile release characteristics and char structural evolution.
研究领域:
化学工程
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2024
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IF 5.8
Yu Han,Zilu Zhang,Boyang Sun,Yan Jiao,Tao Li,Zhihe Li,Weiming Yi,Shaoqing Wang
This study focuses on the use of a molten salt reaction medium (NaCl-KCl-LiCl) in the lignin pyrolysis process to modify the pyrolysis volatiles and biochar structure. The effect of pyrolysis reaction temperature (300°C, 400°C, 500°C, and 600°C) and lignin/molten salt mass ratios (3:1, 1:1, 1:3 and 1:5) on the evolution behavior of volatiles and biochar structure was explored. The pyrolysis products were determined using GS-MS, CO 2 adsorption-desorption analyses, SEM, elemental analysis, proximate analysis, Raman, XRD, and TG/DTG analysis. Results indicated that the introduction of molten salt can enhance the lignin depolymerization, leading to the production of phenolic precursors. Moreover, the metal cation (Na + , K + and Li + ) of molten salt can in-situ induce the modification of biochar structure with high porosity. The lower sulfur content in biochar was attributed to the immobilize function of molten salt. The evolution behaviour of volatiles and biochar structure during molten salt-assisted lignin pyrolysis was proposed. This study can serve as a benchmark for the high-value recycling of industrial lignin waste.
研究领域:
能源与环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
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2021
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IF 7.033
Shasha Liu,Yuhui Wang,Juan Wang,Jianbin Zhou,Xun Hu,Hongqi Sun,Muhammad Asif Akhtar,Hong Zhang,Yong Huang,Shu Zhang
Char-supported metals as catalysts has attracted much attention due to the renewability and structural controllability of char. To understand the effect of char physicochemical structures on the activities of itself and it-supported metal, decomposition of a α−O−4 lignin model compound (benzyl phenyl ether, BPE) over various char-supported Ni catalysts was studied at 400 °C, in which the char supports were prepared at 400 °C, 600 °C, and 1000 °C, respectively. The results showed that the conversion of BPE over the original chars decreased from 17.63% to 7.79% when the preparation temperature of char increased from 400 °C to 1000 °C, while an opposite trend was found for the char-supported Ni, particularly full conversion of BPE was realized when char prepared at 1000 °C was used as the carrier. In addition to the catalysis of Ni, the introduction of Ni improved the graphitization degree and specific surface area of the char support, thus promoting the breakage of C α −O in BPE to mainly generate phenol and toluene. The synergistic effect of char support and Ni on BPE decomposition was demonstrated.
研究领域:
化学工程
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可再生材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Junhao Lin,Shichang Sun,Donghua Xu,Chongwei Cui,Rui Ma,Juan Luo,Lin Fang,Haowen Li
The microwave pyrolysis of biomass and the directional design of biochar structure are examined in this study by exploring the internal connection between energy conversion and biochar structure evolution. Through the optimization of process parameters (microwave power and sample volume), the average utilization efficiency of microwave energy increased from 11.96% to 32.84%, and the specific surface area of the biochar increased from 453.89 m 2 /g to 638.82 m 2 /g. According to the simulation results of the COMSOL Multiphysics software, the distribution of the temperature field was closely related to the evolution of the microwave electric field intensity. The local high temperature areas (hotspots) were primarily located in the center of the biochar, and the temperature distribution gradually decreased from the inside to the outside. The hotspots contributed to the promotion of the conversion of amorphous carbon to graphite carbon. Meanwhile, the graphite carbon with a stronger microwave absorption capacity formed a local hotspot and promoted the growth of the pore structure. The rich pore structure of the biochar facilitated the multiple reflection of microwave energy and prolonged the microwave residence time. Graphite carbon can absorb microwave energy and convert it into heat energy to improve the utilization efficiency of microwave energy. This paper combined the experimental and simulation results to reveal the heat transfer mechanism in the microwave pyrolysis process, which provided a new perspective for the directional reduction of microwave pyrolysis energy consumption and the optimization of the microstructure of biochar.
研究领域:
能源与环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY
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2024
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IF 9
Qiang Hu,Han Zhang,Qiaoting Mao,Jinjiao Zhu,Shihong Zhang,Haiping Yang,Hanping Chen
While numerous research studies have delved into the co-pyrolysis of biomass and plastic waste, limited attention has been devoted to comprehending the interaction mechanism that impacts biomass deoxygenation and carbonization. Therefore, this study explores the co-effect of temperature and polypropylene blending ratio on co-pyrolysis reaction kinetics, distribution of oxygenates/hydrocarbons, as well as the evolution of biochar structure. At a blending ratio of 0.5, the co-pyrolysis exhibits the lowest activation energy (146 kJ/mol), approximately 25.1 % lower than that required for individual pyrolysis . The interaction between bamboo waste with polypropylene increases the O-abstraction process, resulting in the creation of O-containing free radicals and hydrocarbon compounds. The peak proportion of aromatic compounds, reaching approximately 69.5 %, is observed at 700 °C when the blending ratio is 0.5. The H-abstraction process converts large-molecular alkanes into H free radicals and tiny-molecular unsaturated hydrocarbons. The aliphatic functional group content diminishes as the polypropylene ratio increases. The maximum specific surface area (7.70 m 2 /g) and pore volume (21.7 mm 3 /g) are achieved at a blending ratio of 0.75. Notably, polypropylene exerts minimal influence on the graphite crystallite size and graphitization degree of biochar. This research significantly contributes to advancing our understanding of the interaction mechanisms between biomass and plastic waste.
研究领域:
能源与燃料
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环境科学
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生物质转化
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
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2021
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IF 4.43
Yuan Wang,Yuanbo Cai,Hao Zhang,Ji Zhou,Shengtai Zhou,Yang Chen,Mei Liang,Huawei Zou
In this study, the high-performance PDMS elastomer was successfully prepared by constructing epoxy/silicone hybrid network through hydrosilylation and epoxide-opening reaction. The tensile strength , elongation at break and shear strength of the prepared hybrid material were increased by 200.0%, 59.6%, 140.6% respectively when compared with the pure PDMS. The thermal residual weight of the hybrid material at 800 °C in N 2 was kept at 56.9%. The thermal degradation mechanism of hybrid material was investigated through TG-IR analysis. Friedman technique was used to compute the kinetic parameters of degradation reaction. Meanwhile, the composition and structure of residual char of hybrid material after thermal degradation at 800 °C was systematically characterized. Results indicated that the high-performance PDMS elastomer with excellent thermal and mechanical properties was expected to be applied in many prospects such as thermal protective coating, high temperature resistant adhesive and ablative material matrix.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）