SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Xingxing Cui,Hongyang Lyu,Yongming Chai,Bin Liu,Dongfeng Zhao,Chenguang Liu
The strong acidity on the external surface of ZSM-5 is a primary factor resulting in the low BTX selectivity and catalyst deactivation during the olefin aromatization. In this study, a membrane-restricted Silicalite-1@ZSM-5 core–shell structured catalytic catalyst was designed and constructed for 1-hexene aromatization using a hydrothermal coating method. TEM and NMR results confirmed the complete coverage of Silicalite-1 on the surface of ZSM-5, with a shell thickness of 50 nm. The further reaction of the TIPB (1,3,5-triisopropylbenzene) molecular probe reactions demonstrated the passivation of the acid sites on ZSM-5 external surface. The inert shell layer passivated the acid sites on the external surface, thereby suppressing the isomerization of PX and the side-chain alkylation reaction of light aromatics. Compared to ZSM-5, the Silicalite-1@ZSM-5 catalyst exhibited a 37.15 % increase in BTX selectivity, a 58.65 % increase in PX selectivity, significantly reduced coke deposition, and demonstrated better stability. This strategy of in-situ epitaxial growth of inert shell layers holds significant promise for enhancing the selectivity of shape-selective catalysts and extending catalyst lifetime.
研究领域:
催化化学
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材料科学
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石油化工
✓ 已验证
产品关联
DOI
高影响因子
FUEL
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2024
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IF 6.7
Zunlong Hu,Peng Hu,Xiulin Wang,Tongtong Wu,Sida Ge,Haodong Xie,Baijun Liu,Shengli Chen,Zhijie Wu
The hydrocracking catalyst is characteristic of bifunctional catalyst mainly requiring metal–acid balance, which includes metal–acid ratio and metal–acid proximity. Here, we screened and clarified the optimal metal–acid balance on 1-methylnaphthalene (1-MN) hydrocracking by adjusting metal–acid ratio (n M /n A ) via physically mixing the γ-Al 2 O 3 supported NiW samples and Beta zeolite with different acidity (denoted as NiW/AB(x) and x presents the molar ratio of SiO 2 /Al 2 O 3 for Beta zeolite). NiW/AB(60) catalyst with a n M /n A of 0.40 showed the highest BTX selectivity (14.4 %) at a 1-MN conversion of 76.6 %, suggesting an optimal site balance between the metal sulfide site and medium-strong acid sites ( ca . 1:2.5). Also, four different metal–acid proximities with centimeter, millimeter, micrometer and nanoscale distances were compared. The nanoscale proximity enabled the highest BTX selectivity (19.6 %) as compared to the microscale (14.4 %), millimeter scale (12.4 %) and centimeter scale (7.1 %) catalysts, confirming that the selectivity of BTX benefited from the fast diffusion for transporting reaction intermediates between metal and acid sites. Thus, we realized a n M /n A of 0.40 and a nanoscale site proximity for improving the reactivity and selectivity of 1-MN hydrocracking. This work not only presents an elegant showcase of achieving the synergistic effects of bifunctional catalyst, but also provides a rational approach for enhancing the catalytic performance of hydrocracking and beyond.
研究领域:
催化
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化学工程
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石油化学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
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2023
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IF 5.3
Haifeng Tian,Zhiyu Chen,Xing Yang,Peng Gao,Chunxue Jiao,Fei Zha,Yue Chang,Hongshan Chen
A method for the direct synthesis of hierarchical zeolites was developed by converting precursors of zeolites and mesoporous copolymers into homogeneous gels using conventional block copolymers as scaffolds. In this method, hydrothermal synthesis is accomplished on a steam-assisted basis, and the dry gel leaves the system free of the liquid water phase, which successfully avoids phase separation between the soft stencil and the solid silica phase. The catalytic performance of hierarchical zeolites was evaluated on a fixed-bed reactor for the methanol-to-aromatics reaction. The hierarchical structure greatly enhances the catalytic activity of the probe reaction due to the increased outer surface, decreased coke formation, and diffusion resistance in the microporous network. The selectivity of BTX reached 65.8%, and there was no significant deactivation after a reaction of 107 h. The transition state and energy barrier for methanol to aromatics were obtained by the minimum energy search of the LST/QST transition state.
研究领域:
化学工程
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催化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
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2025
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IF 14.9
Wenjun Chen,Yiyi Fan,Yue Liu,Xiaobin Xie,Fan Zhang
Converting waste plastics directly into valuable aromatic chemicals is a promising, cost-effective recycling strategy. Traditional zeolite-catalyzed cracking of polyolefins to produce aromatics often needs high temperatures and faces issues like low selectivity for liquid aromatics, separation difficulties, and rapid catalyst deactivation due to coking. To address this, a multifunctional Ni/HZSM-5 catalyst was developed to efficiently upgrade various polyolefins—including polyvinyl chloride—into gaseous alkanes (C 1 –C 5 ) and easily separable liquid aromatics (C 6 –C 12 ) at 400 °C, without added solvents or hydrogen. Aromatic products make up 57.1 wt% of total output, with more than 97.8% selectivity for the liquid phase and a BTX (benzene, toluene, and xylene) selectivity of 76.1%. The high activity and selectivity for aromatics stem from synergistic interactions between Ni nanoparticles (NPs) and acid sites in the zeolite, which promote selective C–C bond breaking and control hydrogenolysis and aromatization pathways. This synergy allows precise control over the distribution of products by carbon number and favors the formation of separable aromatics. Notably, the catalyst also prevents coking by hydrogenolyzing and hydrogenating reactive intermediates before they form stable graphite-like deposits. Consequently, Ni/ZSM-5 catalyst demonstrates excellent stability, maintaining consistent aromatics yield over 13 consecutive cycles and processing over 30 times its weight in plastics without regeneration. After regeneration, the activity of the catalyst was fully restored, highlighting its potential for industrial use. This work offers valuable insights for designing durable, high-activity catalysts, providing a practical route to improve plastic recycling technologies.
研究领域:
催化化学
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化学回收
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高分子化学
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材料科学
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环境科学
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石油化学
✓ 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）