Sustainable Energy & Fuels
·
2024
·Vol. 9
·期 1
·152-171
·
IF 5
Haoyu Liu,Wenbo Luo,Ke Wang,Yanlin Wang,Hong Yuan
The bolaform surfactant C6H13-N+(CH3)2-C6H12-N+(CH3)2-C6H12-O-C6H4-C6H4-O-C6H12-N+(CH3)2-C6H12-N+(CH3)2-C6H13 (BCPH-6-6-6) was synthesized and used to guide the synthesis of hierarchical ZSM-5 nanosheets (HZN) for use as zeolite catalysts. The number of acidic sites and the Al distribution in the zeolite pores were varied by changing the amounts of sodium sulfate and Al in the initial gel. The X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, NH3 temperature programmed desorption, 27Al magic angle spinning nuclear magnetic resonance spectroscopy and N2 adsorption/desorption were used to characterize these materials. These zeolites each had a well-developed hierarchical system and specific surface areas as high as 631 m2 g−1, indicating that the BCPH-6-6-6 formed lamellar micelles based on π–π stacking. Interconnected hierarchical pore structures were retained after the templating agent was removed. The HZN sample exhibited a 90° rotational intergrowth structure and retained a large number of lamellae. The same material had a high concentration of acidic sites and contained Al in a tetrahedral coordination framework. The catalytic cracking of oleic acid using this zeolite gave light olefin yields up to 52.2% at 500 °C, exceeding the performance of conventional ZSM-5 (38.9%), and the catalyst remained active for up to 60 h. At 450 °C, the BTX selectivity of 6.72% obtained with this material also exceeded that from the conventional ZSM-5. These results were attributed to the connected hierarchical pores of the HZN, which promoted diffusion and provided higher carbon resistance.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2023
·
IF 3.8
Xiaoxue Zhang,Shuman Xu,Jing Hao,Xiaojin Xie,Fengqiu Chen,Dang guo Cheng
Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes (namely 100, 140, and 200 nm) were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide (TPAOH), and investigated in n -heptane catalytic cracking reaction. Diffusional measurements by zero-length column (ZLC) method showed that the apparent diffusivities of n -heptane decreased with the reduction of particle size, indicating the existence of surface barriers. Moreover, with the decrease of particle size, the additional diffusion path length increased, which meant the influence of surface barriers became more apparent. Despite the change of surface barriers, the intracrystalline diffusion still dominated the overall diffusion. Catalytic performance showed that the zeolite with smaller particle size had better stability.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
PETROLEUM SCIENCE AND TECHNOLOGY
·
2017
·
IF 0.655
Lanyu Xing,Zhenhao Wei,Zhenhao Wen,Xuedong Zhu
Hierarchical and conventional ZSM-5 zeolites were synthesized through steam-assisted crystallization approach using acid-treatment kaolin clay as the silica and aluminium sources. The samples were characterized by XRD, SEM, NH3-TPD, N2-physisorption and TG techniques. The results showed that hierarchical ZSM-5 had rich mesopores and bigger specific surface. In conversion of methanol to aromatics, hierarchical and conventional ZSM-5 zeolites showed higher selectivity for aromatics compared with commercial ZSM-5. Under the conditions of 450 °C, 0.15 MPa, the synthesized hierarchical ZSM-5 showed longest lifetime of 380 h, which was 2 and 6 times than those of conventional and commercial ZSM-5, respectively.
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
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2018
·
IF 3.468
Hao Chen,Hao Cheng,Feng Zhou,Kequan Chen,Kai Qiao,Xiuyang Lu,Pingkai Ouyang,Jie Fu
The synthesis of highly selective catalysts for the catalytic fast pyrolysis (CFP) of biomass into valuable aromatics remains a challenge. This report describes the synthesis of hierarchical ZSM-5 catalysts by the NaOH desilication of conventional HZSM-5 for the CFP of rice straw to aromatics in a Tandem μ-reactor system coupled directly to a GC/MS equipped with FID and TCD. Catalysts were treated with a mild HCl wash and metal loading to increase the catalytic activity and reduce the deactivation. The effects of acidity, mesoporosity and incorporation of metals on the production of aromatics were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption and desorption (N 2 -BET) and temperature-programmed desorption of NH 3 (NH 3 -TPD). The highest total acidity, especially the strong acidity, of the hierarchical ZSM-5 treated by 0.2 and 0.4 NaOH followed by HCl washing (AHZ-0.2 and AHZ-0.4) gave the highest yields of aromatics. Suitable mesopores introduced by alkali treatment enhanced mass transfer of reactants, increasing the yield of aromatics. Finally, the loading of a suitable amount of Ni and Cu produced more aromatics than standard HZSM-5 due to the improved decarboxylation/decarbonylation reactions leading to higher yields of olefins.
研究领域:
化学工程
·
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2019
·Vol. 11
·期 8
·2179-2186
·
IF 4.495
Hualei Hu,Danxin Hu,Haitao Jin,Pilan Zhang,Guozheng Li,Hao Zhou,Yong Yang,Chunlin Chen,Jian Zhang,Lei Wang
Graphical In the reaction zone : Benefiting from the presence of the secondary porosity and the appropriately acidity, the hierarchically structured ZSM-5 (HSZ) catalysts exhibited the excellent catalytic performance for the conversion of 2,5-bis(hydroxymethyl)furan (BHMF) to 2,5-bis(ethoxymethyl)furan (BEMF) in a continuous fixed bed reactor. The highest yield of BEMF (90.46 %) was obtained over the HSZ-150 catalyst under the reaction condition of 140 °C, 2.0 MPa of H 2 , and 0.3 h −1 of WHSV. The selective conversion of 2,5-bis(hydroxymethyl)furan (BHMF) to 2,5-bis(ethoxymethyl)furan (BEMF) was investigated in a fixed bed reactor over several heterogeneous solid acid catalysts, including Amberlyst-15, ZSM-5, Mordenite, and a series of hierarchically structured ZSM-5 zeolites (HSZ). The HSZ catalysts exhibited superior catalytic performance to other three commercial catalysts. The highest yield of BEMF (90.46 %) was obtained over the HSZ-150 catalyst under the reaction condition of 140 °C, 2.0 MPa of H 2 , and 0.3 h −1 of WHSV. Moreover, the HSZ-150 catalyst displayed an extremely good stability in the etherification reaction, maintaining more than 80 % yield of BEMF for about 80 h. The outstanding catalytic performance of the HSZ-150 catalyst could be ascribed to that the presence of mesopores enhanced the etherification activity by alleviating the diffusion limitation, and the appropriate acidity improved the BEMF selectivity via suppressing the side reactions.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2018
·
IF 5.807
Leilei Dai,Yunpu Wang,Yuhuan Liu,Roger Ruan,Dengle Duan,Yunfeng Zhao,Zhenting Yu,Lin Jiang
Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N 2 adsorption and desorption (N 2 -BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH 3 (NH 3 -TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2018
·
IF 3.649
Kai Qiao,Feng Zhou,Zheng Han,Jie Fu,Huixia Ma,Guang Wu
Two series of ZSM-5 catalysts with hierarchical porosity were hydrothermally synthesized by adding two types of organosilane reagents (OSA) into the medial synthesis system. The effects of the types and addition amounts of OSA on the pore characteristics, crystallinity, morphology and acidity of the ZSM-5 zeolites were studied by XRD , SEM, TEM , N 2 -adsorption, 27 Al MAS NMR and NH 3 -TPD. Mesopores were generated by introducing appropriate amounts of OSA. In addition, the catalytic performance of the hierarchical ZSM-5s were investigated for the catalytic fast pyrolysis (CFP) of cellulose . The increase in the mesoporosity leads to a reduced amount of coke. However, the highest yield of aromatics was obtained for the mesoporous sample with the greatest microporosity. Thus, the right balance between meso- and microporosity is critical for achieving high aromatic yields. In addition, the distribution of aromatic products is directly related to the microporosity.
研究领域:
化学工程
·
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 10
·1633
·
IF 5.719
Yuan Hu,Chan Wang,Tiesen Li,Xiaojun Bao,Yuanyuan Yue
Aluminum-rich hierarchical MFI-type zeolites with high acidic-site density exhibit excellent activity and selectivity in bulky molecule-involved reactions. However, it is challenging to develop a facile and environmentally benign method for fabricating them. Herein, we employ a polymer that does not contain nitrogen and halogen elements to successfully synthesize aluminum-rich hierarchical ZSM-5 zeolite with a Si/Al ratio of 8 and a significant number of mesopores comprised of oriented-assembled nanocrystals. It is demonstrated that the nitrogen- and halogen-free polymer is instrumental in the formation of the ZSM-5 zeolite by serving as a template for constructing the hierarchical micro/mesoporous structure. Moreover, this polymer also acts as a crystal growth modifier to form a single-crystalline zeolite. Notably, the resultant zeolite shows a better catalytic performance in converting waste plastic into hydrocarbons than a commercial one. Our work enables the synthesis of high-quality hierarchical zeolites without requiring quaternary ammonium templates.Keywords:hierarchical ZSM-5 zeolites;aluminum-rich;nitrogen- and halogen-free polymer;waste plastics cracking
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2025
·
IF 7.5
Ke Yan,Yimin Zhang,Xinyu Xu,Yucai Qin,Yi Mei,Yun Zu
Non-classical crystallization pathways have emerged as a pivotal strategy for the synthesis of zeolites with tailored structures, with the initial feed composition being one of the most critical factors influencing this process. As primary raw material for the formation of zeolite networks, the physicochemical properties of Si sources significantly affected structural and acid properties of zeolites via non-classical crystallization pathways. While, the present operating mechanism between each other was still confusing. In this work, the precipitated silica with tunable Si-hydroxyls was home-made using one-step synthesis of fluorosilicic acid and ammonia aqueous in a SK static reactor. Leveraging this tailored silica, a series of hierarchically layered L-ZSM-5 zeolites were successfully prepared by a non-classical crystallization pathway regulated by Si-hydroxyl engineering. The findings revealed a linear positive correlation between the percentage of layered structures and framework single Al distribution of L-ZSM-5 zeolites and the number of silanol nests present in the precipitated silica. Under comparable conditions, the as-prepared hierarchical L-ZSM-5(7/6) zeolite with more layered structures and framework Al located in the straight/sinusoidal channels exhibited excellent propylene selectivity (44.09 %) and reaction lifetime (25 h, WHSV = 6 h −1 ) in methanol-to-propylene reaction. This work elucidates a decisive relationship between Si-hydroxyls engineering and zeolite crystallization, offering novel insights into the synthesis of zeolites with specific structural features through non-classical crystallization pathways.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2024
·
IF 3.7
Wenbo Luo,Haoyu Liu,Hong Yuan,Hao Liu
Hierarchical zeolites can provide multidimensional spatial networks and, therefore, have significant potential as catalysts for the cracking of biomass to generate light olefins. The present work synthesized the diquaternary ammonium-type surfactant [C18H37–N+(CH3)2–(CH2)6–N+(CH3)2–C6H13]Br2, incorporating hydrophobic 18-carbon alkyl groups for usage as a structure-directing agent. This compound was subsequently used to prepare nanosheets of a hierarchical ZSM-5 two-dimensional zeolite (HNZSM-5) through a one-pot hydrothermal method. The crystal phase, morphology, and hierarchical structure of the HNZSM-5 were analyzed using various techniques, including X-ray diffraction, electron microscopy, and N2 adsorption/desorption. When applied to the catalytic cracking of a waste cooking oil model compound, the HNZSM-5 exhibited superior activity and stability compared with a conventional ZSM-5. This performance was attributed to the more accessible acid sites and unique lamellar structure of the former material. The HNZSM-5 also outlasted the conventional zeolite, showing deactivation after 45 h of reaction compared with 20 h, indicating exceptional stability and excellent resistance to coking.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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