ACS Catalysis
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2021
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IF 13.084
Ting Wang,Yuebing Xu,Yufeng Li,Lei Xin,Bing Liu,Feng Jiang,Xiaohao Liu
Conversion of syngas into aromatics via the Fischer–Tropsch (FT) route provides a promising way to supply the value-added chemicals. However, it is still a great challenge to achieve controllable aromatics selectivity with good stability. Herein, we report the Na-mediated bimetallic Fe–Ni catalyst simply particle mixed with HZSM-5, which can boost the stable and selective production of aromatics from the syngas. In detail, FeNiOx(5:1)-0.41Na exhibits quite stable catalytic activity with notably higher selectivity to light α-olefins (C2=–C4=) compared to α-Fe2O3-0.75Na. Various characterizations suggest that an appropriate addition of Ni with Na substantially regulates iron carbide formation and suppresses carbon deposition owing to the electron donation of Fe to Ni reducing CO adsorption and dissociation. Interestingly, extra Na results in remarkably increased selectivity to C1o–C4o, despite the fact that Na shows the ability to suppress hydrogenation. Both characterizations and density functional theory (DFT) calculations demonstrate that the addition of Na weakens the Fe–Ni interaction and reduces electron transfer from Fe to Ni, which promotes C1o–C4o formation as Ni tends to reflect its intrinsic catalysis. DFT calculations confirm that the adsorbed CH2 species at the Ni–Fe interface prefers to undergo coupling to form C2H4, and the formed C2H4 spontaneously desorbs from the surface, indicating that the formation of lower olefins is favorable and further chain growth is inhibited. This could be attributed to the fact that the accumulated electron at the Ni–Fe interface weakens the binding strength of CH2 and C2H4 species because of electronic repulsion. Furthermore, the effects of FT product distribution on aromatics formation were also investigated. FeMnOx(5:1)-0.40Na produces longer olefin-rich hydrocarbons in C5+ owing to oxygen vacancy-assisted CO dissociation, leading to highly branched monocyclic aromatics and faster HZSM-5 deactivation because of increased coking from the isomerization–hydrocracking of long hydrocarbons. In contrast, FeNiOx(5:1)-0.41Na-HZSM-5 produces major light aromatics about 65.7% including toluene, ethyl-benzene, and xylene in total aromatics with about 98.6% aromatics in the liquid phase, which benefits from the fact that FeNiOx(5:1)-0.41Na makes shorter hydrocarbons in C5+ and/or Ni metal has a strong ability of H2 dissociation to provide atomic H spillover onto HZSM-5. Thus, HZSM-5 also shows improved stability. Note that the mixed catalysts with a high Na content indicate a substantial Na+ migration to increase light α-olefins in the gas phase owing to suppress H-transfer reaction. This study provides deep insights into how to develop stable and selective iron-based catalysts for the production of FT products and its further conversion into value-added light aromatics.
研究领域:
催化化学
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材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
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2017
·Vol. 7
·期 12
·383
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IF 3.082
Nana Li,Yadong Bi,Xiaoqiang Xia,Hui Chen,Jianli Hu
The hierarchical HZSM-5 zeolite was prepared successfully by a simple NaOH treatment method. The concentration of NaOH solution was carefully tuned to optimal the zeolite acidity and pore structure. Under NaOH treatment conditions, a large number of mesopores, which interconnected with the retained micropores, were created to facilitate mass transfer performance. There are very good correlations between the decline of the relative zeolite crystallinity and the loss of micropores volume. The Ni nanoclusters were uniformly confined in the mesopores of hierarchical HZSM-5 by the excessive impregnation method. The direct deoxygenation in N2and hydrodeoxygenation in H2of the methyl laurate were compared respectively over the Ni/HZSM-5 catalysts. In the N2atmosphere, the deoxygenation rate of the methyl laurate on the Ni/HZSM-5 catalyst is relatively slow. In the presence of H2, the synergistic effect between the hydrogenation function of the metal and the acid function of the zeolite supports can make the deoxygenation level more obvious. The yield of hydrocarbon products gradually reached the maximum with the appropriate treatment concentration of 1M NaOH, which could be attributed to the improved mass transfer in the hierarchical HZSM-5 supports.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Qi Lu,Yuanzhe Gong,Jianwen Lu,Jian Liu,Yulong Wu
Stearic acid (SA) and hexadecanamide (HA), which are model compounds of algae-based bio-oil, were used to produce aromatics for catalysis by a hierarchical HZSM-5 zeolite under hydrothermal conditions. The results showed that the hierarchical HZSM-5 zeolite was more active than the traditional HZSM-5 parent zeolite. The molar yield of toluene, ethylbenzene, and xylene could reach (1.14 ± 0.05) × 100% (normal weight percentage yield = 40.77 wt %) when the reaction temperature was 400 °C. Moreover, the catalyst was stable and recyclable under hydrothermal conditions. Besides, the addition of acetic acid remarkably improved the deoxygenation (or denitrification) and aromatization efficiencies of the SA and HA mixture by more than 25%. This study provides a feasible approach to the valorization of algal biomass and the production of aromatics.
研究领域:
化学工程
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催化
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生物能源
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可再生能源
✓ 已验证
产品关联
DOI
高影响因子
Applications in Energy and Combustion Science
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2025
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IF 6
Zhongyue Zhou,Haoran Liu,Xinghua Liu,Chih-Hao Chin
Coke deposition and catalyst deactivation represent significant challenges in catalytic research, yet the mechanisms underlying their formation remain inadequately understood. Herein, we employed the HZSM-5 catalyzed conversion of furfural as a model reaction and, using a newly developed online high-resolution mass spectrometry (HRMS) technique, directly detected a broad spectrum of oxygenated polycyclic aromatic hydrocarbons (OPAHs) under reaction conditions. Solid-state NMR further revealed the functional group architectures of OPAH side chains in condensed-phase coke, while density functional theory (DFT) calculations elucidated plausible formation and transformation pathways. These complementary approaches establish that highly active OPAHs serve as crucial intermediates in the coke deposition process. We propose a novel mechanism in which light OPAHs, orginating from small-molecule products, undergo rapid polymerization at the active sites to yield larger polycyclic aromatic hydrocarbons, traditionally classified as coke. This newly identified mechanism highlights the unexpectedly rapid coking during the catalytic pyrolysis of biomass, and underscores the significant role of OPAHs in catalyst deactivation. By providing molecular-level insights into coke growth, this study lays a foundation for strategies to suppress coke formation, thereby improving the efficiency and sustainability of catalytic conversion technologies for biomass utilization.
研究领域:
催化化学
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生物质能源
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石油化学
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分析化学
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理论化学
✓ 已验证
产品关联
DOI
高影响因子
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