POLYMER DEGRADATION AND STABILITY
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2026
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IF 8.1
Shanshan Lin,Ge Yang,Xiaolin Zhao,Hailing Guo,Hao Wu,Ning Zheng,Svetlana Mintova,Zhibo Li
Polyethylene terephthalate (PET) glycolysis using heterogeneous catalysts is often limited by the poor accessibility of polymer chains to catalytic active sites, particularly in microporous systems. Herein, undercoordinated Zn Lewis acid sites were constructed on the external surface of ZSM-5 through controlled Zn modification, while strong interactions between Zn species and framework-associated Al enhance both Lewis acidity and catalyst stability. The resulting accessible Lewis acid sites facilitate polymer-catalyst contact, enabling complete PET conversion within 30 min under mild glycolysis conditions. The catalyst exhibited a high Zn utilization efficiency of 24.7 g PET ·g Zn -1 ·min -1 , maintained stable catalytic performance over 10 cycles with negligible Zn loss, and remained effective for post-consumer PET feedstocks. This work demonstrates that engineering the spatial distribution and coordination environment of Lewis acid sites is an effective strategy for heterogeneous polymer depolymerization.
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ACS Applied Materials & Interfaces
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2022
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IF 10.383
Weijiong Dai,Lina Zhang,Runze Liu,Guangjun Wu,Naijia Guan,Landong Li
Zeolites with good acid site accessibility and high diffusion rates are highly desirable catalysts, especially when dealing with bulk molecules. In this work, ZSM-5 zeolites with similar Si/Al ratios but different thicknesses along the b-axis (from ∼30 nm to ∼5 μm), namely, two plate-like ZSM-5 zeolites and two reference zeolites have been prepared and the impacts of b-axis thickness on the surface properties and catalytic cracking performances are explored. Comprehensive physiochemical studies demonstrate that reducing the b-axis thickness of the zeolite crystals endows the samples with better acid site accessibility and more external surface acid sites. Two model compounds with different molecule sizes, namely, 1,3,5-triisopropylbenzene (TIPB) and cumene, are selected to explore the catalytic cracking performances of the as-synthesized samples. The results reveal that decreasing the b-axis thickness of zeolite crystals can effectually promote the catalytic activity and stability in catalytic cracking reactions. For TIPB cracking, the greatly enhanced catalytic activity is ascribed to the enhanced acid site accessibility in plate-like ZSM-5 zeolites, and for cumene cracking, the improved catalytic stability is ascribed to the shortened diffusion length of plate-like zeolites.
研究领域:
催化化学
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材料科学
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化学工程
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石油化工
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纳米多孔材料
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Canadian Journal of Chemistry
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2022
·Vol. 100
·期 8
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IF 1.051
Changshuai Liu,Rong Zhang,Rujing Pei,Chao Zhang,Fuxiang Li
A new strategy was implemented to synthesize hierarchical ZSM-5 zeolite, which uses self-made organosilanized double-terminal amino polyetheramine (ODAP) as a soft template to generate mesopores. The influence of the additional amount of ODAP on the textural properties and morphologies of the hierarchical ZSM-5 zeolite was investigated. The obtained hierarchical ZSM-5 zeolite was characterized by X-ray diffraction, N2 physical adsorption, SEM, temperature-programmed desorption of NH3, and other methods. The analysis of the experimental results shows that the maximum total BET specific surface area and mesoporous specific surface area of the optimized hierarchical ZSM-5 zeolite reached 609 and 278 m2/g, respectively. Because the synthesized hierarchical ZSM-5 zeolite has a large mesoporous specific surface area and abundant surface acidity, in terms of reactant conversion and product selectivity, compared with microporous zeolite, it exhibits excellent catalytic performance in the thiophene alkylation desulfurization reaction. This synthesis strategy can be extended to the preparation of zeolites with different framework structures, which is of great significance.
研究领域:
材料科学
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催化化学
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无机化学
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多孔材料
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ACS Catalysis
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2025
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IF 13.1
Xu Li,Guodong Qi,Richard J. Lewis,Mark J. Howard,Barry A. Murrer,Brian Harrison,David J. Morgan,Christopher J. Kiely,Qian He,Thomas E. Davies,David J. Willock,Michael Bowker,Jingxian Cao,Feng Deng,Jun Xu,Graham J. Hutchings
The selective oxidation of methane to form methanol and acetic acid has been studied using AuPd nanoparticles supported on the zeolite H-ZSM-5 in water at 240 °C using molecular oxygen as the terminal oxidant in the absence of any added coreductant. The addition of Pd to Au/ZSM-5 significantly increases the selectivity to acetic acid to levels approaching almost complete selectivity within the oxygenated products. However, we observe that the reaction conditions employed lead to the corrosion of the stainless-steel components of the autoclave reactor and also leaching of iron from the ZSM-5 zeolite, and hence the AuPd nanoparticles, on reaction, become coated or partially coated with an oxidic Fe shell. The presence of the oxidized iron coating hinders nanoparticle agglomeration preventing deactivation of the AuPd/ZSM-5 catalyst but does not adversely affect the observed catalysis.
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Chemical Engineering and Processing-Process Intensification
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2023
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IF 4.3
Xi-shuo Wang,Ying-jiao Li,Ting-ting Qi,Ji-wen Fu,Guang-Wen Chu,Bao-chang Sun
In industry, H-type zeolites are usually synthesized under hydrothermal conditions in the sodium-containing system, in which great deal of ammonia nitrogen wastewater will be produced during the transformation of zeolites from Na-type to H-type. In this work, we prepared ZSM-5 zeolites in the sodium-free system using organic amines in a rotating packed bed (RPB), which can greatly reduce the amount of wastewater. It was found that the ZSM-5 zeolites synthesized by isopropanolamine (MIPA) had the highest acid amount with a value of 2.331 mmol/g compared to that by other three amines, and exhibits the highest conversion of benzaldehyde with a value of 77.63% in the acetal reaction of benzaldehyde and ethylene glycol . More importantly, RPB premixing can improve the transfer of Al into the framework of ZSM-5 zeolites relative to conventional stirring technique. This work provided a new route to prepare ZSM-5 zeolites with high acid amount in sodium-free system.
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Surfaces and Interfaces
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2022
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IF 6.137
Dongjing Liu,Lingtao Yang,Jiang Wu,Bin Li
Zeolite ZSM-5, as a crystalline microporous material , has attracted widespread interest in diverse research areas because of its big specific surface area, high thermal stability, and shape selectivity . Here, x Bi 2 S 3 /ZSM-5 compounds is easily synthesized using a molten salt method and employed to capture elemental mercury in the temperature range of 60–260°C. Pristine ZSM-5 displays a weak Hg 0 adsorption capability. Bi 2 S 3 decoration can greatly reinforce the mercury adsorption capability of ZSM-5 due to addition of active sulfide species. 20Bi 2 S 3 /ZSM-5 with 20 wt% Bi 2 S 3 loading value performs optimally toward Hg° capture associated with a mercury removing efficiency of 90.8–96.5% within 100–140°C. In addition, 20Bi 2 S 3 /ZSM-5 is nearly impervious to NO and SO 2 with respect to mercury removal. One-dimensional nanorod structure of Bi 2 S 3 and big specific surface area of ZSM-5 probably account for the superior mercury capture performance of x Bi 2 S 3 /ZSM-5 compounds.
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Catalysis Science & Technology
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2022
·Vol. 12
·期 24
·7281-7292
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IF 6.177
Hui Chen,Wei Li,Mingchao Zhang,Wangyang Wang,Xian-Hua Zhang,Fa Lu,Kang Cheng,Qinghong Zhang,Ye Wang
Propane dehydroaromatization (PDA) to high value-added aromatic hydrocarbons, such as benzene, toluene, and xylene (BTX), is an attractive but challenging process. The traditional Zn/H-ZSM-5 or Ga/H-ZSM-5 catalysts can offer considerable PDA performances but still suffer from low activity and poor stability because of harsh reaction conditions. Here, we report a multifunctional Pt–Zn@H-ZSM-5 catalyst that exhibits a significantly improved performance in the PDA reaction at 550 °C, with a single-pass propane conversion of 74%, aromatics selectivity of 56%, and CH4 selectivity of only 4.7%. The yield of aromatics is twice as much as those of Zn/H-ZSM-5 and Ga/H-ZSM-5 catalysts. We have demonstrated that the Pt–Zn alloy nanoparticles with an average size of 2.4 nm are uniformly confined within H-ZSM-5 crystals, providing atomic-scale proximity between metal and zeolite acid sites. This unique structure enhances not only the dehydrogenation of the propane feedstock in the initial reaction stage but also the dehydrogenation of cyclic C6+ hydrocarbons by the recombinative desorption of surface hydrogen species in the last stage while suppressing the side hydrogenolysis and hydrogen-transfer reactions. Furthermore, the Si/Al ratio of H-ZSM-5, the synergistic effect between platinum and zinc, and the location of Pt–Zn nanoparticles over composite catalysts have also been discussed. These findings suggest that via bimetallic alloying and rational arrangements of functional sites at the nanoscale, the multistep PDA reaction can be greatly intensified.
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JOURNAL OF RARE EARTHS
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2022
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IF 4.632
Feng Lin,Yudan Zhong,Yulong Ma,Yonggang Sun,Xiuqin Men,Yingbo Zhu
Hydrodeoxygenation (HDO) of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance. However, developing new catalysts with high activity and excellent stability in an aqueous phase faces considerable challenges. Rare earth doping can effectively regulate the water exchange rate constant (WERC) value of the catalyst and play an important role in promoting the hydrolysis of ether bonds. Therefore, in this paper the bimetallic supported catalyst Ni–La 2 O 3 /H-ZSM-5 doped with rare earth metal La 2 O 3 was prepared, and used to catalyze the conversion of the lignin model compound guaiacol to cyclohexanol in the aqueous phase. The conversion of guaiacol catalyzed by 10Ni–3La 2 O 3 /H-ZSM-5 reaches 100%, and the selectivity of the product cyclohexanol is 85%. A series of characterizations illustrate that the doping of La 2 O 3 causes the electron transfer between La 2 O 3 –Ni and changes the distribution of Ni, and a strong metal carrier interaction occurs between the bimetallic Ni–La 2 O 3 and H-ZSM-5. This can effectively promote the hydrolysis of the C–O ether bond in guaiacol and significantly improve the activity of the catalyst. The possible catalytic reaction mechanism of Ni–La 2 O 3 /H-ZSM-5 catalytic conversion of guaiacol was proposed.
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JOURNAL OF MEMBRANE SCIENCE
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2021
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IF 8.742
Shuang Wang,Liangqing Li,Jiajia Li,Jiaxuan Wang,Enze Pan,Jinming Lu,Yan Zhang,Jianhua Yang
High-performance zeolite socony mobil five (ZSM-5) membranes were successfully prepared on a cheap, tubular α-Al 2 O 3 support via a proposed wet gel conversion (WGC), aiming at avoiding the competitive zeolite crystals growth in the solution and ensuring the formation of polycrystalline zeolite layer onto the support surface. A small amount of gel was loaded on seeded tubes via dip-coating and then converted to ZSM-5 membranes via direct crystallization without using any additional synthesis solution for membrane growth. By using this method, the amount of synthetic gel was largely reduced as compared with the traditional hydrothermal synthesis . The effects of crystallization temperature, crystallization duration, and synthetic gel silica source dissolution duration on the morphologies, microstructures, and pervaporation performances of ZSM-5 membranes were investigated. Under optimized synthesis conditions, the as-synthesized ZSM-5 membrane showed high separation performance and stability in isopropanol dehydration. During the 104-h pervaporation test, the permeation flux was stable at 2.96 kg m −2 h −1 with a separation coefficient exceeding 10,000. The synthetic route exhibited excellent reproducibility for the fabrication of highly water-selective ZSM-5 membrane. This work provides a novel, feasible method for the preparation of zeolite membranes with high performance, high atom economy, low cost, and reduced waste solution.
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JOURNAL OF APPLIED POLYMER SCIENCE
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2020
·Vol. 138
·期 1
·49611
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IF 2.52
Zongqi Zhang,Yuanfeng Wu,Lijing Gao,Guomin Xiao
This work aims at investigating the special application of ZSM-5/polydimethylsiloxane (PDMS) membrane being used for pervaporation separation of levulinic acid aqueous solutions. The effects of temperature, downstream pressure, feed concentration, and raw material ratio on the separation performance are investigated by self-made flat-sheet films. When the flow rate of feed pump remained at 0.4 ml/min (10 wt% levulinic acid), a levulinic acid permeation flux of 334.13 g/(m 2 h) and a separation factor of 2.382 at 75°C are observed over the composite membrane doped with 10 wt% ZSM-5. In addition, the acid resistance is enhanced after the PDMS membranes are doped with ZSM-5. Besides, the functionalized process also makes the membranes increase in its hydrophobicity. The results demonstrate that the ZSM-5/PDMS-based membranes show profound prospects for separating levulinic acid aqueous solution.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
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IF 4.939
Zhaowei Li,Xiaosong Yang,Yingxiang Han,Long Rong
The conversion of biomass to produce high-valued chemical aromatic intermediates such as benzene (B), toluene (T), ethylbenzene (E), xylene (X), naphthalene (N) has attached booming interests. Herein, in order to obtain BTEXN aromatics on the hydrocracking of Jatropha oil, several LaNiMo/ZSM-5 catalysts (La loading from 0.5 to 15 wt%) by alkali treatment and metal impregnation methods were synthesized and investigated. Fundamentally, we found the alkali treatment engendered more mesoporosity to ZSM-5 and resulted in higher catalytic activity . It bears emphasis that further metal impregnated catalyst NiMo/ZSM-5 could improve the aromatics yield due to the increase of metal active sites and acidity sites. Besides, we noted that La loading had positive effects on coke reduction, catalytic stability and catalyst lifetime. To sum up, results confirmed the favorable 1 wt% La–NiMo/ZSM-5 had maximum 75 wt% BTEXN yield, longer catalyst lifetime for 100 h and decreased carbon deposits by 1.11%.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2021
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IF 5.455
Yanliang Zhai,Yunshan Shang,Luoming Zhang,Xiaoling Meng,Yanjun Gong,Lirong Zheng,Jing Zhang,Ping Liu
Hydrothermally modified nanosheet ZSM-5 zeolite by directly using MnO x nanoparticles was carried out and this substantially offered a high performance catalyst for methanol to propylene (MTP) reaction. The properties of as synthesized ZSM-5 nanosheets with different MnO x amounts (NS-x) were compared with ZSM-5 nanosheets modified by impregnation method (IM-0.5) and physically mixed method (PM-0.5), respectively. The initial state of MnO x nanoparticles was close to Mn 2 O 3 with 20 nm in size. XRD , H 2 -TPR and XAFS results confirmed under high temperature hydrothermal condition, the Mn 2 O 3 nanoparticles disaggregated into Mn 2 O 3 clusters and entered the framework defects of nanosheet zeolite with high dispersion. Infrared spectra of hydroxyl groups (OH-IR) showed that the Mn 2 O 3 clusters were bonded with silanol defects both on the surface and inside zeolite, which substantially increased the stability of Mn 2 O 3 clusters and healed the framework defects. In contrast, the Mn species in the impregnated sample was close to the co-existence of Mn 2+ ions and MnO 2 nanoparticles with 2–3 nm, no interaction between Mn species and Si–OH group was determined. Notably, the typical sample (NS-0.5) with MnO x cluster modification performed much higher propylene selectivity and catalytic stability (~52%, 240 h, WHSV = 3 h −1 ), while the conventional IM-0.5 and PM-0.5 showed poor propylene selectivity (48%, 46%) and catalytic stability (166 h, 133 h) in MTP reaction. The excellent result should be attributed to the subtle control of external strong acid and the less structural defects, due to specific existence of bonded Mn 2 O 3 clusters.
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