MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Mingwei Zhang,Linlin Liu,Wenjun Zhang,Li Wang,Xiangwen Zhang,Guozhu Li
ZSM-48 is widely used to support Pt nanoparticles (Pt/ZSM-48) for hydroisomerization of long-chain n -paraffin due to its 10-member-ring one-dimensional pore structure . But the yield of target isomers on Pt/ZSM-48 is difficult to be improved due to easily bundled crystal bars and relatively excessive acid sites of ZSM-48, which restricts reactant diffusion and causes cracking. In this study, different types of zeolite growth modifiers (ZGMs) are screened for regulating the physicochemical property of ZSM-48, in which phenolic hydroxyl was found to be the most effective functional group. Quantitative correlations between ZGM structure and the properties of corresponding ZSM-48 crystal are achieved based on appropriate descriptors and multi-parameter regression. Then, the mechanism of ZSM-48 regulation by phenolic ZGMs is revealed. The models predict that polydopamine (PDA) is a superior ZGM for hydroisomerization, which is verified by textural characterization and reaction evaluation. Compared with the conventional catalyst, the isomer selectivity was improved effectively from 92% to over 97% when the feed conversion was lower than 80%, and the maximum yield of isomers was 89.0% as catalyzed by the PDA-regulated catalyst. The as-built models can also be used to design preferred phenolic ZGMs for preparing tailored ZSM-48 in other applications.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
FUEL
·
2025
·
IF 7.5
Wei Zhang,Yuting Wang,Jiangnan Xiang,Haiying Lu,Wenrui Jin,Yan Wang,Bo Qin,Weijiong Dai,Binbin Fan,Jiajun Zheng,Ruifeng Li
In this paper, a nanoparticle-stacked ZSM-48 molecular sieve is prepared by modifying the gel preparation process through stepwise crystallization. The corresponding bifunctional catalyst is developed for the hydroisomerization reaction of n -dodecane. The physicochemical properties of ZSM-48 are characterized and analyzed using XRD, SEM, NH 3 -TPD, N 2 adsorption–desorption and zero-length column (ZLC) method. The crystal size of Z-48-T2 synthesized via the stepwise synthesis method is reduced to as small as 0.6 μm, and its acidity is lower compared to that of Z-48-C. Meanwhile, Z-48-T2 exhibits the highest HF value and demonstrates excellent diffusion properties. Consequently, the Z-48-T2 catalyst shows superior catalytic activity and isomerization selectivity, achieving the highest iso -C 12 yield of 83.8 %. The outstanding diffusion performance of Z-48-T2 results in a monomethyl isomerization yield approximately 21 % higher than that of conventional ZSM-48 molecular sieves. Despite these improvements, the final mono-branched isomer product distribution remains unchanged, with 5-methylundecane being the predominant mono-branched isomer for both Z-48-T2 and Z-48-C.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2025
·
IF 4.2
Wenjun Zhang,Mingwei Zhang,Linlin Liu,Songzu Tang,Li Wang,Xiangwen Zhang,Guozhu Li
Preparation of robust catalysts with high isomer yield still poses challenges for efficient hydroisomerization of long-chain n-alkanes. ZSM-48 is a competitive candidate for a support due to its unique one-dimensional pore structure. However, its excessive acidic sites lead to serious cracking side reactions. Herein, a facile one-pot in situ method of trace cerium doping in ZSM-48 is developed, and the acidity property and structure of ZSM-48 are finely tuned by changing the Ce content. Compared with traditional ZSM-48, Ce-doped ZSM-48 has smaller specific surface area and microporous volume, and the concentration of strong Brønsted acid sites is effectively adjusted. Pearson correlation coefficients between the properties of ZSM-48 zeolite regulated by different amounts of Ce and the catalytic hydroisomerization performance of Pt/ZSM-48 are calculated, which demonstrate that strong Brønsted acid sites of ZSM-48 are significantly correlated with n-hexadecane isomerization yield. ZSM-48 doped with 0.41 wt% Ce with appropriate concentration of Brønsted acid sites shows superior hydroisomerization performance, reaching an iso-hexadecane yield of 87.0%.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
Catalysis Science & Technology
·
2019
·Vol. 9
·期 9
·2132-2143
·
IF 5.726
Jie Zhang,Zhihua Huang,Lanjian Xu,Xiaomin Zhang,Xinzhi Zhang,Yangyang Yuan,Lei Xu
The methanol to hydrocarbons reaction over a unidimensional 10-membered-ring zeolite, H-ZSM-48, was investigated in the temperature range of 723–973 K. C3–5 olefins were the dominant products of reaction at 723 K. Multiple approaches (constant, transient, co-feed and isotope labelling experiments) have been adopted to clarify the underlying reaction pathway. The results indicate that both of the olefin- and aromatics-based cycles contribute to light olefin formation, and the aromatics-based cycle can be significantly enhanced with increasing reaction temperature. Ethene is formed predominantly from the aromatics-based cycle while propene and higher olefins are mainly derived from the olefin-based cycle. The 12C/13C-methanol isotopic switching experiments manifest that hexamethylbenzene is the most active aromatic intermediate. Co-feeding of 13C-methanol and 12C-benzene at 543 K reveals that the paring mechanism is the dominant mechanism for aromatic dealkylation. More importantly, the first experimental evidence that the two carbons of ethene are derived from aromatic ring carbons is obtained based on the isotopic pattern. Furthermore, the investigation on coke-covered H-ZSM-48 reveals that the reaction of methylbenzenes occurs mainly inside the channels. This work will shed new light on the reaction pathway of the MTH reaction over unidimensional zeolites.
研究领域:
化学工程
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催化科学
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DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2025
·
IF 7.7
Wei Zhang,Jiangnan Xiang,Yuting Wang,Mengxi Ma,Yan Wang,Bo Qin,Weijiong Dai,Binbin Fan,Jiajun Zheng,Ruifeng Li
In this paper, a one-dimensional ten-membered ring microporous molecular sieve ZSM-48 is employed as a model catalyst, with the number and positional distribution of acid sites in ZSM-48 molecular sieve adjusted by regulating the temperature of templating agent exfoliation. XRD, FT-IR, SEM, TG, NH 3 -TPD, N 2 adsorption-desorption, and the zero-length column (ZLC) method are used for characterization and analysis. The decrease in the distribution depth of acid sites within the microporous channels of ZSM-48 will not only significantly affects the hydroisomerization performance of n -dodecane (resulting in a final yield of isododecane of more than 80 %) but also influences the yield ratio of multi-branched and mono-branched isomers. After the conversion is stabilized, the yield ratio of multi-branched to mono-branched isomers for Z-48-350 is 1.4 to 2.1 times higher than that for Z-48-550. Furthermore, acid site distribution depth profoundly influences reactant diffusion, with Z-48-120 exhibiting a 115 % higher effective diffusion constant than Z-48-550 at 140 °C. Shortening the distribution depth of acid sites in the micropores does not significantly change the product distribution of n -dodecane monomethyl isomers but markedly suppresses the cracking reaction due to reduced diffusion limitation of olefinic intermediates. This enables efficient and selective hydroisomerization of long-chain n -alkanes.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Jipeng Meng,Di Bai,Pahaer Zeyaodong,Chuang Li,Xiao Chen,Changhai Liang
The wirelike, rodlike and corolla-like ZSM-48 zeolites with various SiO 2 /Al 2 O 3 ratios (SARs) were successfully synthesized and exploited for the hydroisomerization of n-hexadecane (n-C 16 ). The influences of metal-acid balance, acid sites quantity, crystal morphology and textural properties on n-C 16 hydroisomerization performance were investigated primarily, via various characterization technique such as XRD , FT-IR, SEM, TEM, N 2 physisorption , NH 3 -TPD, and Py-IR. The C Pt /C A ratios of various catalysts were calculated for the quantified expression of the metal-acid balance, and the acid sites quantity was seriously crucial for the consecutive acid-catalyzed reaction after C Pt /C A ratios satisfied within an ideal range. Large external surface could accelerate the conversion rate, shorten the diffusional constraints and inhibit the cracking. The superiorities of satisfied C Pt /C A values (0.12–0.15), high concentration of acid sites (>230 μmol/g) and large external surface (>120 m 2 /g) persuaded the Pt/Z(P)80, Pt/Z(H)60 and Pt/Z(H)80 samples to demonstrate wonderful hydroisomerization performance with outstanding yield around 80 wt% and excellent i-C 16 selectivity over 91 wt%. Although Pt/Z(W)80 and Pt/Z(R)80 samples owned the relatively small crystal, the gloomy catalytic activity of them was observed due to their relatively low concentration of acid sites and external surface. Moreover, the presence of “key-lock” mechanism was verified by the observations of 7-methyl-pentadecane (7MC15) dominating in isomer products.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 51
·28909-28917
·
IF 2.936
Haoran Li,Chenglian Liu,Yan Wang,Jiajun Zheng,Binbin Fan,Ruifeng Li
ZSM-48 and ZSM-22 zeolites with similar Si/Al molar ratio have been treated with alkali to modify the pore structures and acidity, and alkali treated ZSM-22 and ZSM-48 samples have been characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), N2 adsorption/desorption, Nuclear Magnetic Resonance (NMR), NH3-Temperature Programmed Desorption (NH3-TPD) and Pyridine-Fourier Transform Infrared Spectroscopy (Py-FTIR). Characterization results indicate that NaOH treatment could improve the mesoporous structure for both ZSM-22 and ZSM-48. NaOH treatment modifies the acidity of ZSM-22 and ZSM-48 diversely. The n-hexane hydroisomerization performances of Pt supported protonic form ZSM-22 and ZSM-48 (Pt/HZSM-22 and Pt/HZSM-48) bifunctional catalysts have been evaluated in a fixed bed reactor. Catalytic results indicate that catalytic activity and selectivity depend on both pore structure and acidity of zeolites. In comparison of Pt/HZSM-22 and Pt/HZSM-48, Pt/HZSM-22 shows better n-hexane hydroisomerization performance at relatively low temperature (<300 °C), meanwhile, at relatively high temperature (>300 °C) Pt/HZSM-48 exhibits better catalytic performance. Moreover, alkali treated Pt/HZSM-48 could produce more di-branched isomer compared with alkali treated Pt/HZSM-22.
研究领域:
催化
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化学工程
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Yifan Zheng,Hongxin Ding,Enhui Xing,Jinghua Zhou,Yibin Luo,Jichang Liu,Kake Zhu
ZSM-48 is a unidimensional zeolite that is frequently used as acid component of bi-functional hydroisomerization catalyst. As selectivity towards unwanted cracking products increases with retention time of isomerized products inside micropores, shortening their retention time inside the micropores by reducing channel length offers an effective way to improve isomerization selectivity. Direct synthesis of unidimensional zeolitic crystals with reduced channel axis is particularly difficult, since they habitually grow into rod-like shape along their channel direction. Post-synthetic bead-milling is a cost effective, mechanochemical method to decrease crystal size of zeolites from micro meter to nano meter scale, but suffers from amorphization or partial destruction of zeolitic crystals. Consequently, a post-milling recrystallization process is often entailed to remedy the destructed domains, which, nonetheless, readily causes secondary crystal growth and formation of bulky crystals that compromises the effect of bead-milling. Here, we show that porogen-assisted recrystallization can overcome the problem to fabricate channel axis reduced ZSM-48 nanocrystals. The Si/Al ratio is tunable between 30 and 200 and the acidity is largely preserved after recrystallization. The catalytic advantages of the obtained material are demonstrated in catalytic n -heptane hydroisomerization. The obtained ZSM-48 nanocrystal with Si/Al ratio of 100 outperforms the rest samples and shows enhanced isomerization yield (72% vs 62%) with respect to the parent sample. By combined diagnoses of the impact of diffusion length on product selectivity (product shape selectivity) and kinetic studies , selectivities to monomethyl branched isomers (2-methyl hexane and 3-methyl hexane) and small bulky dimethyl branched isomers (2,3- and 2,4-dimethyl pentane) are attributed to product shape selectivity, whereas the formation to bulky dimethyl branched isomers (2,2- and 3,3-dimethyl pentane) is hindered mainly by transition-state shape selectivity. The combined destructive-constructive synthetic protocol and the revelation of the origin of shape-selectivity in n -heptane hydroisomerization are useful for hydroisomerization catalyst design.
研究领域:
催化材料
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化学工程
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2022
·Vol. 9
·期 9
·2016-2022
·
IF 7.779
Risheng Wang,Zhihua Peng,Pingping Wu,Hongman Sun,Yu Zhang,Fazle Subhan,Hailiang Yin,Youhe Wang,Zifeng Yan
Rational design of organic structure-directing agents (OSDAs) is always regarded as a promising strategy to produce ZSM-48 with diverse configurations. However, to date, only OSDAs with alkyl and alkenyl groups have been employed to produce *MRE zeolites with different structures. Aromatic heterocyclic groups were rarely considered for the synthesis of ZSM-48 with a unique nanostructure. In this work, a triazine-based bolaform quaternary ammonium bifunctional template was designed for the first time to fabricate nanorod stacked hierarchical ZSM-48 (NSH-ZSM-48). Nanorod-stacked ZSM-48 with different SiO2/Al2O3 ratios ranging from 100 to 500 was obtained via a conventional procedure, using the synthesized s-triazine based OSDA, and a reasonable formation mechanism was proposed based on geometrical matching. We also demonstrated that the ZSM-48 nanorods piled up to form an ordered bird's nest-like hollow sphere configuration. The synthesized NSH-ZSM-48 possesses abundant mesopores and a high surface area, attributed to the SDA's mesopore-forming and nanonrod's stacking abilities. In contrast to conventional materials, 1 wt% Pd/NSH-ZSM-48 experiences a dramatic increase in the conversion (3.59%) and selectivity (95.7%) of a cyclohexanol/cyclohexanone mixture in the selective oxidation of cyclohexane, which are higher than those for silicalite-1 and SBA-15 with the same loading (2.11%/66.1% and 1.76%/68.5%, respectively).
研究领域:
化学工程
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材料科学
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催化化学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Shiao Gao,Ahui Ma,Zhennan Yang,Sida Ge,Zhuwen Zhang,Zhijie Wu
ZSM-48 zeolite is characteristic of 10-member ring (10-MR) one-dimensional tubular channel structure and finds extensive applications in catalytic hydroisomerization reactions. Here we developed an efficient synthetic strategy for low-silica ZSM-48 zeolite with a SiO 2 /Al 2 O 3 ratio at 30–176 via a seed-assisted hydrothermal synthesis method, overcoming the limit that 1,6-hexanediamine (HDA) template can only be used to synthesize high-silica (i.e., SiO 2 /Al 2 O 3 ratio >200) zeolites. A two-step crystallization procedure coupled with zeolite seed-assisted synthesis strategy was enrolled to realize well crystallized ZSM-48 zeolites, in which the zeolite nuclei are sufficiently produced at the nucleation temperature at 100 °C for 24 h with the aid of zeolite seeds, and the zeolite growth is proceeded at the crystallization temperature at 160 °C for 48 h. The morphology and particle size of low-silica ZSM-48 zeolite have been manipulated by adjusting the synthetic parameters, such as the alkalinity and silicon source of aluminosilicate gel for zeolite, the crystallization manner (static or dynamic crystallization), as well as the presence of additive (i.e., sodium chloride). The as-synthesized ZSM-48 zeolite possesses a high acid content of 0.194 mmol/g, highlighting its potential as an excellent acidic support for hydroisomerization catalysts. The cost-effective and environmentally friendly synthesis strategy, which is anticipated to expand the application of alkylamine organic templates in the synthesis of low-silica ZSM-48 zeolite.
研究领域:
材料科学
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化学工程
·
催化
·
无机化学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Jipeng Meng,Chuang Li,Xiao Chen,Chengye Song,Changhai Liang
Synthesis of highly-crystallized ZSM-48 zeolite with low SiO 2 /Al 2 O 3 ratio was successfully performed via seed-assisted route. The influence of various factors on the seed-assisted synthesis was investigated systematically, including the seeds dosages, different seeds species, adding order of seeds, hydrothermal temperature and time, silica and aluminum sources, and gel compositions. The crystallinity, morphology, textural and acidic properties of ZSM-48 were characterized by various techniques, such as XRD , SEM, FTIR, Py-IR, N 2 physisorption , 29 Si and 27 Al MAS NMR. Aluminum sources posed a critical influence on the crystallinity with NaAlO 2 more beneficial to obtain well-crystallized ZSM-48, whereas the crystallinity seemed slightly susceptible to silica sources. SEM results revealed that the crystal size was significantly reduced from ca. 20 μm to around 2 μm after introduced the seeds. Kinetic analysis suggested that the added seeds can significantly reduce the apparent activation energy of nucleation and crystallization, encourage the formation of crystal nuclei and promote crystallization. The Pt-supported seed-assisted samples exhibited considerably higher density of acid sites than that loaded on seed-free sample. The hydroisomerization of n -hexadecane was investigated over various Pt-supported catalysts, and the Pt-supported seed-assisted samples exhibited the highest i-C 16 yield of ca. 75 wt% at conversion over 87 wt%.
研究领域:
催化
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
TRANSACTIONS OF TIANJIN UNIVERSITY
·
2026
·
IF 7.8
Gong Mengcong,Wang Qingfa,Liu Linlin,Zhang Xiangwen
ZSM-48 zeolite, which features one-dimensional ten-membered-ring straight channels, is an ideal support for hydroisomerization catalysts to improve fuel low-temperature fluidity. To improve the poor low-temperature fluidity of Fischer–Tropsch synthesis products, this study employed Mg modification on Pt/ZSM-48 catalysts to optimize their hydroisomerization performance. A series of Mg-Pt/ZSM-48 catalysts with varying Mg loadings was prepared via incipient wetness impregnation. The effects of Mg modification on the pore structure, acidity, and metal–acid balance of the Pt/ZSM-48 catalyst system were systematically investigated. Catalytic performance was evaluated using n-hexadecane as a model compound. The Mg species selectively modified the micropore channels, decreasing the specific surface area and micropore volume. Moreover, Mg 2+ selectively neutralized Brønsted acid sites, reducing the concentration of medium-strong acid sites and Brønsted acidity while introducing Lewis acid sites, thereby lowering the Brønsted/Lewis acid ratio. Appropriate Mg modification optimized the metal–acid balance, making acid-catalyzed skeletal isomerization the rate-determining step. Although the Mg-modified catalysts exhibited moderately reduced catalytic activity, their isomer selectivity and yield were significantly enhanced. The 0.5 Mg-Pt/Z48 catalyst achieved an isomer yield of 81.81% at 91.18% conversion, representing a 9% improvement over the unmodified catalyst. The micropore confinement effect weakened the interaction between alkane molecules and micropore channels, promoting the key–lock catalytic mechanism. This increased the formation of mono-branched isomers close to the center of the main carbon chain, significantly improving the low-temperature fluidity of the fuel. This study provides a simple and efficient strategy for designing high-performance hydroisomerization catalysts for long-chain n-alkanes. Graphical
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DOI
高影响因子
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