MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Fuxiang Feng,Xiaopo Niu,Li Wang,Xiangwen Zhang,Qingfa Wang
Ni/ZSM-5 nanosheet catalysts with different Si/Al ratios were modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) to tailor their acid spatial distribution. Their catalytic performance was evaluated with the hydroconversion of oleic acid to aviation-fuel-range-alkanes (AFRAs) at different reaction temperatures and H 2 pressures. The modified catalysts inherit the nanosheet structure with decreased external Brønsted acid concentration, especially the strong one. External Brønsted acid sites mainly favor the cracking of the deoxygenated products (C 17 /C 18 ). Internal Brønsted acid sites mainly enhance the isomerization of the linear AFRAs. And the catalytic activity of the external Brønsted acid sites was more sensitive to reaction temperature than that of the internal ones. The deoxygenation and cracking reactions were also more sensitive to H 2 pressure compared to the isomerization reaction. High AFRA selectivity of 51.4% as well as high iso/n -alkanes ratio of 1.7 were achieved at 250 °C and 10 bar over NS200(1).
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高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2017
·Vol. 93
·期 5
·1347-1358
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IF 3.135
Yu Shen,Fumin Wang,Zongzhuang Han,Xubin Zhang
BACKGROUND ZSM-5 zeolites are of great importance in industrial catalysis. However, the diffusion limitations caused by small pore opening restrict the extent of catalytic conversions over conventional ZSM-5. Many studies have shown that mass transfer in zeolite channels can be improved by controlling the morphology or creating additional mesoporosity. Here, the catalytic performance is further improved by the creation of hollow structure and intracrystalline mesopores in ZSM-5 zeolite. RESULTS The characterization results demonstrated that hollow ZSM-5 with intracrystalline mesopores can be synthesized by using a simple one-step hydrothermal strategy with a commercial gemini-type cationic surfactant containing hydrophilic hydroxyl groups. Compared with the Fe-substituted conventional ZSM-5, the Fe-substituted hollow ZSM-5 with intracrystalline mesopores show remarkably enhanced catalytic performance in the hydroxylation of phenol. About 52.2% conversion of phenol can be obtained with almost 96.8% selectivity to dihydroxybenzenes. The catalytic activity remained almost unchanged after five cycles. CONCLUSION The newly created hollow structure and intracrystalline mesopores in ZSM-5 zeolite showed enhanced catalytic activity and reusability for the hydroxylation of phenol, which is higher than most reported systems. The prepared catalyst is a promising alternative material for the hydroxylation of phenol. © 2017 Society of Chemical Industry
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Yong Zhang,Huiping Zhang,Ying Yan
A heterogeneous catalyst (Cu/ZSM-5) was prepared by a metal-organic chemical vapor deposition (MOCVD) method under nitrogen atmosphere using Cu(acac) 2 as the copper precursor, and further characterized by XRD , AAS , SEM, BET, H 2 -TPR and XPS as well as catalytic activity performance for the oxidation of toluene. N 2 adsorption data revealed that the samples (CVD-4) prepared by MOCVD with calcination at 500 °C for 4 h possessed higher surface areas than that (CVD-BC) not calcined. The results of XPS demonstrated that CVD-4 exhibited higher redox property and more surface oxygen species compared with CVD-BC and IM (Cu/ZSM-5 catalyst prepared by impregnation). In particular, the CVD-4 catalysts prepared by MOCVD with calcinations showed the highest catalytic activity for toluene oxidation with 90% conversion of toluene at 293 °C with the feed concentration of 1000 ppm and GHSV of 15,000 h −1 , which was lower than IM (310 °C). The results of a reaction durability test revealed that the Cu/ZSM-5 catalysts prepared by MOCVD possessed excellent durability for toluene oxidation for 63 h, while the conversion of toluene fell down from 90% to 60% after 48 h over IM catalyst.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Lingwu Meng,Maosheng Lin,Qirui Guo,Longzhao Zhang,Xiangyu Huang,Shule Zhang,Weihua Ma
Stabilizing metal species at the atomic level and tuning their catalytic properties is a significant challenge. Herein, an N-doped Fe x O y -N-ZSM-5 catalyst with layered and chain-like graphene structures is reported. The catalyst can selectively catalyze the oxidation of triethylamine (TEA) with an efficiency of 99.7 % at 240 °C, and maintain an N 2 yield of 97.6 % over the reaction temperature range of 240–360 °C. The results indicate that the layered graphene in the catalyst provide anchor sites for active Fe, while the abundant chain-like graphene act as connectors between ZSM-5 and the layered graphene, offering ample opportunities for TEA and its intermediates to contact the catalyst surface. This increases the number of active sites on the catalyst, thereby enhancing the catalytic performance of Fe x O y -N-ZSM-5. Notably, due to the interaction between FeO x and FeN x species, Fe x O y -N-ZSM-5 exhibits excellent thermal stability and water resistance, demonstrating promising potential for practical.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2025
·
IF 8.3
Li Cui,Yimin Wang,Zhen Yuan,Xiaoli Zhang,Yuewen Chen,Xiya Zhang,Yihu Ke,Zhile Xiong,Hai Liu
Oxidizing glycerol (the primary by-product of biodiesel production) into 1,3-dihydroxyacetone (DHA) can significantly boost the economic feasibility of the biodiesel industry, but the catalyst deactivation remains a significant challenge. Herein, we present a novel approach that achieves a breakthrough in the conversion of glycerol to DHA through the integration of porous zeolite platform (bio-ZSM-5), derived from corn straw templates, with the traditional Au/CuO catalyst via mechanical milling. Under alkali-free conditions, the synthesized Au/CuO@bio-ZSM-5 catalyst exhibits remarkable glycerol conversion rate of 97.3% and DHA selectivity of 92.2%. Notably, the catalyst retains its efficacy with a glycerol conversion of 89.7% and DHA selectivity of 90.3% even after three regeneration cycles, surpassing all previously documented catalysts for this specific reaction. Serial characterizations and density-functional theory (DFT) calculations reveal that the incorporation of bio-ZSM-5 can modify the electronic structure of surface Au, reduce the adsorption energy of glycerol, and elevate the reduction temperature. This work is expected to provide an effective perspective for the design of catalysts with high cyclic stability.
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高影响因子
RSC Advances
·
2015
·Vol. 5
·期 77
·63044-63049
·
IF 3.84
Hualei Hu,Jinghui Lyu,Jie Cen,Qunfeng Zhang,Qingtao Wang,Wenwen Han,Jiayao Rui,Xiaonian Li
The effect of MgO and Pd modification on the catalytic performance of hierarchical porous ZSM-5 for benzene alkylation with methanol was investigated. The results indicated that the introduction of MgO could reduce the Brönsted acid sites which suppressed the side reaction of methanol to olefins and in turn effectively promoted the alkylation of benzene. However, the single modification of MgO could not completely suppress the formation of ethylbenzene and coke. Doping a small amount of Pd had a positive effect on inhibiting the generation of ethylbenzene and coke, which could be attributed to the hydrogenation of ethylene into ethane on Pd. The dual modified catalyst (MgO and Pd) exhibited high benzene conversion (56%) and xylene selectivity (39.1%), and the lowest ethylbenzene selectivity (0.13%) and coke content (0.4 wt%).
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Zhanyu Qian,Yinghao Wu,Wenjie Zhao
Glass fiber reinforced polymer coatings (GFRPC) are used to protect steel structures in harsh marine environments due to high mechanical strength and chemical stability. The composite coating not only suffers from impact damage by seawater and sediment but also experiences corrosion damage in the splash zone. However, the GF has weak interfacial adhesion with polymer resins due to the chemical inertia and smooth surface, which limits the service lifespan of GFPRC. Hence, ZSM-5 zeolite were in situ prepared on the surface of glass fibers by hydrothermal synthesis, and 2-mercaptobenzimidazole (MBI) was further adsorbed to obtain difunctional hybrid glass fibers (ZGFM) to enhance the interfacial adhesion strength of glass fiber/resin and also the erosion resistance and anti-corrosion ability of composite coatings. Compared to GF/EP, the interfacial shear strength of ZGFM/EP was increased by 104.39 %. After immersion under an alternating hydrostatic pressure of 20 MPa for 12 days, the impedance value of the ZGFM/EP composite coating remained at 6.40 × 10 9 Ω•cm 2 , demonstrating outstanding deep-sea anti-corrosion performance. Following the erosion test, the ZGFM/EP exhibited a reduction in mass loss and volume loss by 10.65 % and 12.55 %, respectively, in comparison to the pure EP coating. The excellent interfacial strength between ZGFM and EP ensured effective stress transfer, which prevented crack propagation, thus enhancing the mechanical properties and erosion resistance of the composite coating. Meanwhile, electrochemical experiment proves glass fiber with MBI loaded obviously inhibits the corrosion reaction.
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CHINESE CHEMICAL LETTERS
·
2017
·
IF 1.932
Muhammad Ammar,Yan Cao,Peng He,Li-Guo Wang,Jia-Qiang Chen,Hui-Quan Li
A set of mono- and bimetallic (Zn-Co) supported ZSM-5 catalysts was first prepared by PEG-additive method. The physicochemical properties of the catalysts were investigated by FTIR, XPS, XRD, N 2 adsorption-desorption measurements, SEM, EDS and NH 3 -TPD techniques. The physicochemical properties showed that the ZnCo 2 O 4 spinel oxide was formed on the ZSM-5 support and provided effectual synergetic effect between Zn and Co species for the bimetallic catalyst. Furthermore, bimetallic supported ZSM-5 catalyst exhibited weak, moderate and strong acidic sites, while the monometallic supported ZSM-5 catalyst showed only weak and moderate or strong acidic sites. Their catalytic performances for thermal decomposition of hexamethylene–1,6–dicarbamate (HDC) to hexamethylene–1,6–diisocyanate (HDI) were then studied. It was found that the bimetallic supported ZSM-5 catalysts, especially Zn-2Co/ZSM-5 catalyst showed excellent catalytic performance due to the good synergetic effect between Co and Zn species, which provided a suitable contribution of acidic sites. HDC conversion of 100% with HDI selectivity of 91.2% and by-products selectivity of 1.3% could be achieved within short reaction time of 2.5 h over Zn-2Co/ZSM-5 catalyst.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2017
·
IF 2.843
Changsheng Zhang,Qinming Wu,Chi Lei,Shuxiang Pan,Chaoqun Bian,Liang Wang,Xiangju Meng,Feng-Shou Xiao
Large crystalline particles of ZSM-5 zeolites (S-ZSM-5) have been successfully synthesized by adjusting crystallization time and Si/Al ratios in the starting solid mixtures in the absence of water solvent. Catalytic tests in the methanol-to-olefins (MTO) reaction show that these S-ZSM-5 zeolites obtained from the solvent-free route exhibit superior catalytic properties including excellent propylene selectivity and extraordinarily long life in the MTO reaction. Particularly, when the crystallization time is 30 h and the Si/Al ratio in the starting solid mixture is adjusted at 150 under the solvent-free conditions, the S-ZSM-5-30h-150 catalyst with the large particle sizes (10–20 μm) gives propylene selectivity as high as 50.0% and catalyst life as long as 9 h, which are much better than those (propylene selectivity at 38.9% and catalyst life of 3 h) of the conventional ZSM-5 zeolite with smaller crystals (ca. 5 μm) synthesized from the hydrothermal route. High-resolution TEM images of these S-ZSM-5 zeolites demonstrate that there is mesoporosity in the samples. More interestingly, these mesopore size distributions could be adjusted by the crystallization time during the solvent-free synthesis. Obviously, the presence of mesoporosity is very favorable for the mass transfer, and an appropriate Si/Al ratio in the zeolite framework could offer suitable acidic density for the catalytic conversion, which should be responsible for the superior catalytic properties in the MTO over the S-ZSM-5-30h-150 catalyst. The features of mesoporosity in the S-ZSM-5 crystals and sustainability for the solvent-free synthesis could be potentially important for wide applications of these S-ZSM-5 zeolites in the future.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2024
·
IF 5.8
Xue-Yu Ren,Jing-Pei Cao,Ming-Wen Ma,Xiao-Yan Zhao
We have created a self-assembly method to synthesize the mesoporous structure (SBA-15 and MCM-48) in micro-ZSM-5 by a seed induced crystallization. The micro/mesoporous MCM-48@Z5 composite display the complement effect of micro/mesopores structure in the aromatic yield and coke deposits during catalytic fast pyrolysis of lignite towards aromatics, compared to SBA-15@Z5. Impressively, the mesoporous MCM-48 from the epitaxial growth of ZSM-5 crystal achieved the high alkyl-substituted aromatics in the upgraded tar. By contrast, the developed mesopores in SBA-15@Z5 composites presented the low content of aromatics owing to insufficient acidity. Moreover, from the analysis of the coke nature and composition deposited on the spent zeolites, it can be found that the coke species possessed the light species ( i.e. , benzene, naphthalene and it’s derivatives) and heavy species ( i.e. , long-chain aliphatics), similarly to the coke species on ZSM-5. The coke growth strongly depends on the polymerization on the surface area during catalytic fast pyrolysis of lignite towards aromatics, despite more mesopores on catalysts.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Jingce Bi,Qingfeng Zhan,Yujing Chen,Zhiqiang Liang,Ningning Liu,Xia Zhang,Zhuopeng Wang,Yide Han
At present, the construction of hierarchically porous ZSM-5 molecular sieves using only cetyltrimethylammonium bromide (CTAB) as the template represents a major challenge in the field of molecular sieve synthesis. In this work, hierarchically porous ZSM-5 zeolite was synthesized via a straightforward conventional static hydrothermal method, employing CTAB as the sole template agent derived from CTAB-encapsulated silica sphere precursors. By controlling the dissolution rate of silica spheres, the release rate of CTAB is regulated, enabling the synthesis of pure-phase hierarchical porous ZSM-5 zeolite. The influences of alkalinity, aging time, Si/Al ratio, CTAB content and addition method, and crystallization time on the construction of hierarchically porous ZSM-5 molecular sieves were examined. The experimental results indicate that the crystallization process in this system proceeds in the order: MFI → MFI + kenyaite → MFI + quartz. Additionally, by managing the crystallization process, we systematically examined the formation process of impurities and established the optimal conditions for synthesizing pure-phase hierarchically porous ZSM-5 molecular sieves in this system. Moreover, the as-prepared hierarchically porous ZSM-5 molecular sieves demonstrated enhanced selectivity towards light olefins in the MTP reaction.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Nengcui Zhang,Yimin Zhang,Feng Wu,Ziyan Liu,Xinyu Xu,Qiang Li,Yi Mei,Yun Zu
Phosphorus (P)-doping H-ZSM-5 zeolites, which is crucial for industrial applications, aim to adjust both acidity and framework stability while optimizing product distribution in heterogeneous catalysis. Nonetheless, current phosphating methods often suffer from inadequate phosphorus dispersion and unclear interfacial interactions with framework aluminum (Al). In this work, P-doping ZSM-5 zeolites were successfully one-step prepared by using tributylphosphine served as an organophosphorus precursor, assisting by density functional theory calculations. On account of this, a stable interface of tetracoordinated-phosphorus and framework Al was fabricated uniformly. Such an interfacial structure not only made more framework Al sit in the straight/sinusoidal channels, but also remodeled Brønsted acid sites and reinforced its acidity. Under comparable conditions, methanol-to-propylene (MTP) evaluations indicated that the high-silica PZ-75 zeolite catalyst displayed an appreciable catalytic lifetime (30 h) and a higher C 3 H 6 selectivity (52.4 %). Additionally, in-situ Fourier transform infrared spectroscopy further revealed that this exceptional MTP performance was attributable to the predominant olefinic pathway and lower hydrogen transfer ability. These results provide valuable information for cognizing phosphorus-zeolite chemistry and creating high-performance MTP catalytic materials.
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PubMed
高影响因子
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