Materials Research Express
·
2019
·Vol. 6
·期 11
·115540
·
IF 1.449
Yong Liu,Qiong Luo,Hao Lu,Zhao Wang
The factors influencing the hydrothermal synthesis of ZSM-5 have been investigated in detail, such as silicon source, template, pH, reaction temperature, etc The type of template plays a key role. It is difficult to synthesize ZSM-5 without template or using inorganic template under our research conditions. However, the organic template of tetrapropylammonium bromide (TPABr) or n-butylamine (BTA) is beneficial to the synthesis of HZSM-5. The pH range of 10.79–11.14 is favorable for the synthesis of HZSM-5 zeolite. When temperature is greater than or equal to 160 °C, the synthesis of target zeolites is easy. However, if temperature is ≤140 °C, the synthesized product belongs to amorphous solid. Scanning electron microscopy (SEM) shows that the morphology of HZSM-5 crystal is hexagonal columnar. Fourier transform infrared (FTIR) analysis shows the synthesized product has a good ZSM-5 skeleton structure. The synthetic HZSM-5 zeolite has the BET specific surface area of about 387.326 m2 g−1. The adsorption capacities of the synthesized HZSM-5 for phenol, quinoline and indole can reach up to 43.54 mg g−1, 83.10 mg g−1 and 69.51 mg g−1, respectively.
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BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Lin Jiang,Yunpu Wang,Leilei Dai,Zhenting Yu,Qi Yang,Sha Yang,Deyu Jiang,Zhiyun Ma,Qiuhao Wu,Bo Zhang,Yuhuan Liu,Roger Ruan
A ZSM-5/SiC composite catalyst was synthesized and characterized by Brunauer–Emmett–Teller analysis, X-ray diffraction, and scanning electron microscopy in this study. The composite catalyst had the characteristics of ZSM-5 and SiC, and the surface of SiC grew evenly with a layer of ZSM-5. The effect of the composite catalyst on the product distribution and chemical composition in a co-pyrolysis downdraft system was investigated. In a down system with a catalytic temperature of 450 °C, a feed-to-catalyst ratio of 2:1, and a soybean-soapstock-to-straw ratio of 1:1, the proportions of alkanes, olefins, aromatics, and phenoxy compounds were 6.82%, 4.5%, 73.56% and 11.11%, respectively. The composite catalyst combined the catalytic performance of ZSM-5 and SiC, increasing the proportion of aromatics and decreasing the proportion of oxygen-containing compound in the bio-oil. Moreover, the composite catalyst maintained its activity after reusing several times.
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高影响因子
JOURNAL OF CATALYSIS
·
2019
·
IF 7.723
Xiaoyue Wan,Qi Zhang,Mingming Zhu,Yi Zhao,Yongmei Liu,Chunmei Zhou,Yanhui Yang,Yong Cao
Site-selective deoxygenation of hydroxyl groups represents essential processes to access valuable functionalized bio-based compounds with industrial potential. One of the challenging tasks in this context is to convert biodiesel-derived glycerol in the presence of abundant water directly to 1,3-propanediol (1,3-PDO), a key component of the emerging polymer industry. Herein, a monometallic iridium supported on H-ZSM-5 in the absence of Re oxophilic metal oxides was prepared via grinding-assisted impregnation procedures and attempted as an effective and recyclable catalyst for the aqueous-phase selective hydrogenolysis of glycerol toward 1,3-PDO in the absence of acid additives. The results revealed the necessity to control the Ir domain dispersions, Ir 0 /Ir 3+ ratio and the amounts of overall acid/Brönsted acid sites. Activity depended linearly on the amount of overall and Brönsted acid sites, and 1,3-PDO selectivity increased in the presence of Ir-induced Brönsted acid sites, denoted as Ir-O(H)-H-ZSM-5. We speculate that Ir-O(H)-H-ZSM-5 are generated by the interfacial synergistic interaction between IrO x and H-ZSM-5 through hydrogen spillover and reverse hydrogen spillover according to the reported literatures. The reaction mechanism to elucidate the role of Ir-O(H)-H-ZSM-5 sites in glycerol hydrogenolysis was also postulated based on extensive characterization and catalytic reaction results.
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JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Qin Zhu,Jiaorong Yan,Qiguang Dai,Qingqing Wu,Yuanpu Cai,Jinyan Wu,Xingyi Wang,Wangcheng Zhan
A unique zeolite catalyst, Fe doped ZSM-5 microsphere assembled by uniform nanorod-like crystals with hierarchical pore structure, was successfully synthesized and applied for the adsorption and degradation of trace chlorobenzene (CB) in the presence of H 2 O 2 . The organic ferric salts as the precursors, ethylene glycol as a chelating/reducing agent and the dynamic two-stage temperature-varied hydrothermal technique, together made the synthesized hierarchical Fe-ZSM-5 nanorods assembled microspheres (FZ-CA-5EG) to be characterized by abundant highly dispersed and valency-controlled framework Fe 3+/2+ species. As a result of these features, the FZ-CA-5EG showed excellent ability of adsorption and degradation efficiency of CB, and enhanced durability due to negligible leaching of framework Fe species. Moreover, the hydroxyl radicals were determined as the main the reactive oxygen species of CB oxidation degradation, and a possible adsorption-oxidation degradation pathway was proposed.
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PubMed
高影响因子
JOURNAL OF POROUS MATERIALS
·
2018
·Vol. 26
·期 3
·793-802
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IF 1.858
Wu Hong,Wang Xianshu,Liu Fei,Cao Jianxin
The SAPO-34/ZSM-5 composite catalyst (SZ-TS) was successfully fabricated using a two-step in situ crystallization method. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, N 2 adsorption–desorption, and ammonia temperature-programmed desorption measurements were used to characterize the synthesized catalysts and evaluate their catalytic performances on methanol-to-olefin (MTO) reaction. The synthesis mechanism of two-step in situ crystallization was further investigated. Results showed that the SZ-TS synthesized by two-step in situ crystallization featured an intimately bonded composite structure owing to the synergistic effects of the interface. However, the physical mixture of SAPO-34 and ZSM-5 (SZ-PM) presented two discrete phase structures. By using the composite catalyst in MTO reaction, the SZ-TS exhibited the longest life of 1400 min, which was much higher than that of SZ-PM (720 min). Methanol conversion reached 97.3%, and the selectivity for light olefins totalled 93.0%. The excellent catalytic performance of SZ-TS was attributed to the hierarchical pore structure and suitably weak acid site distribution. Via pre-crystallization, alkalinity can be adjusted in the adjacent ranges of SAPO-34 and ZSM-5. By adding the pre-crystallized alkaline SAPO-34 slurry into the strong alkaline system of the parent ZSM-5 slurry, phase dissolution of SAPO-34 in the secondary crystallization solution was avoided. The external surface of SAPO-34 was etched in the alkaline environment of the secondary crystallization solution, resulting in hierarchical pore distribution, which benefited the MTO reaction. This in situ synthesis method features the advantages of simplicity, low time consumption, and low cost. Therefore, this approach possesses the potential to satisfy the demands of the MTO market.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yimin Zhang,Yonglin Ren,Yun Zu,Ke Yan,Yibin Luo,Enhui Xing,Yucai Qin,Yi Mei,Xingtian Shu
Available hierarchization and phosphorization of ZSM-5 zeolite as one of methanol-to-propylene (MTP) catalysts have improved reactive stability and propylene selectivity, but are subjected to the problems of poor phosphorus stabilization efficiency and inhomogeneous dispersion. Herein, we fabricate a series of hierarchical P@ZSM-5 zeolites via one-step disassembly-reassembly-phosphating strategy of ZSM-5 zeolite using successfully self-created asymmetric quaternary phosphonium hydroxides and elucidate the mechanism of mesoporous formation and the interaction of phosphorus with framework aluminum. Delightfully, reconstructively tetracoordinated P IV -O-Al IV structure endows excellent hydrothermal and Brønsted acid stability of hierarchical P@ZSM-5 zeolites. The MTP tests show that the P@ZSM-5(TBuCP) catalyst prepared by disassembly-reassembly-phosphating of tributylhexadecylphosphine hydroxide (TBuCPOH) exhibits superior propylene selectivity (48.9 %) and remarkedly long lifetime (32.5 h, WHSV=6h −1 ). Such enviable MTP performance is benefited from the join hands of the zeolitic hierarchization and suitable Brønsted acid strength conferred by its phosphorus-aluminum interaction that are conducive to olefinic cycle process. These findings afford value-filled opportunities in novel MTP catalysts with high reactive stability and propylene selectivity, and the understandings for phosphorus-zeolite chemistry.
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CATALYSIS COMMUNICATIONS
·
2024
·
IF 3.4
Chenan Yang,Yi Liu,Ying Hu,Peng Wang,Yuling Yang,Shangxing Chen,Zongde Wang,Xiang Li
Catalytic valorization of biomass into high energy density fuels plays a vital role in order to achieve future carbon neutrality. Herein, a class of H-MZ-5 catalysts with different mesoporous pore structures and acid site properties were synthesized. Among them, HMZ-5 prepared with tetrapropylammonium bromide (TPABr) and hexadecyltrimethylammonium bromide (CTAB) as templating agents showed the most excellent catalytic activity and selectivity of α-pinene dimerization. Under optimal catalytic conditions, 100% α-pinene was converted with 89.6% selectivity to dimers. The efficient catalytic activity and affordability of the catalysts in this system make it promising for industrial applications.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2024
·
IF 5.8
Yingna Li,Muhammad Sajjad Ahmad,Mudassir Hussain Tahir,Maryam Bashir,Arif Muhammad Khan,Rana Muhammad Irfan,Imran Riaz Malik,Boxiong Shen
This study investigates the selective production of aromatics through the co-pyrolysis of cabbage waste and plastics followed by catalytic reforming with Ni-modified ZSM-5. Co-pyrolysis significantly improves the inflection point (a parameter for determining thermal stability) to 251.3 °C from 232.7 °C. This process also enhances the relative yield of olefins and phenols , which are precursors for aromatic production to 25.46 and 17.23 respectively, up from 13.87 to 12.05. Furthermore, catalytic pyrolysis elevates the relative yield of aromatics to 53.4, as confirmed by Thermogravimetric Analysis (TGA) and Thermogravimetric-Fourier Transform Infrared Spectroscopy (TG-FTIR) analyses. GC-MS confirms the enhanced formation of valuable chemical precursors via co-pyrolysis such as phenols and olefines to 18.67 % and 22.13 % leading to a 63.81 % selective yield of aromatics in the final oil with 10Ni/ZSM-5. Ni modification of ZSM-5 is influential in decreasing PAH formation (7.26 % from 20.37 %), indicating that this two-step process is an effective method for transforming waste into high-quality bio-oil with enriched aromatic content.
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Journal of Inorganic and Organometallic Polymers and Materials
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2024
·
IF 3.9
Liu Hao,Wang Yanlin,Yuan Hong,Luo Wenbo
Nanoscale ZSM-5 zeolites (NZSM-5) having different crystal sizes and Si/tetrapropylammonium hydroxide (TPAOH) molar ratios were synthesized using a hydrothermal method. These materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N 2 adsorption–desorption. The results showed that each zeolite was highly crystalline regardless of the Si/TPAOH ratio and that the Brunauer–Emmett–Teller surface areas were in the range of 329−392 m 2 /g. The random aggregation of these nanoparticles resulted in the formation of numerous intergranular mesopores. These NZSM-5 zeolites were applied to the catalytic cracking of oleic acid to prepare light olefins and light aromatics using a laboratory-scale fixed bed reactor. The zeolite having a Si/TPAOH ratio of 10/5 showed the best catalytic activity and provided light olefins yield of 55% and selectivity of BTX in liquid phase products of 18%, respectively, at 500 °C. The small crystal size and abundant intergranular mesopores in this specimen resulted in shorter diffusion paths and an increase in the external specific surface area that both inhibited coke deposition and ensured accessible acid sites. Graphical Abstract
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Wei Zhao,Yinan Xu,Yuehui Qiao,Rui Sun,Jie Qian,Yixue Wang,Quan Liu,Zhekun Shi,Fandong Meng,Xiaoli Zhan,Qinghua Zhang
Zeolites have been widely utilized in the adsorption of volatile organic compounds (VOCs) due to their high specific surface area and robust stability. However, the adsorption capacity of zeolites for VOCs is considerably reduced under humid conditions due to the competitive adsorption between water and VOCs, thereby limiting their industrial applicability. Herein, we report a core–shell ZSM-5@NiAl-LDH (Z-L) composites designed specifically for efficient adsorption of VOCs under high humidity conditions. The core–shell architecture is achieved by introducing active sites onto the ZSM-5 framework pretreated with high-alkalinity agents, followed by the growth of NiAl-LDH on its surface, creating a regular, vertically staggered structure. Compared with ZSM-5 zeolite, Z-L composites show a larger specific surface area, wider pore size, and larger mesopore volume, allowing a high adsorption capacity of the VOCs. Contact angle and static adsorption tests of water molecules reveal that the LDH shell effectively increases the hydrophobicity of Z-L composites. The dynamic adsorption behavior for m-xylene demonstrates that Z-L composites exhibit significantly enhanced adsorption capacity, 3.79 times that of ZSM-5 zeolite. Furthermore, Z-L composites exhibit a higher selectivity for m-xylene at 60 % relative humidity, achieving a Q wet /Q dry ratio of 86.7 %, outperforming most porous adsorption materials. Kinetic model analysis reveals that the augmentation of mesopores in Z-L composites enhances the effective diffusion space for synthesized samples, resulting in exceptional adsorption performance. This novel synthetic material is anticipated to be a promising candidate for VOCs pollution control in high-humidity environments.
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JOURNAL OF THE ENERGY INSTITUTE
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2024
·
IF 5.6
Shunnian Xu,Zhiguo Sun,Kaijun Hou,Gang Wang,Meijia Liu,Yahong Zhang,Chenwei Zhang,Zhongdong Zhang
Undesirable side reactions often occur during the catalytic pyrolysis of olefins in FCC gasoline to produce light olefins. We proposed a method to maximize light olefin selectivity by suppressing these side reactions. In this study, P-ZSM-5 and Ce–P-ZSM-5 were prepared by the pore volume impregnation method to investigate the regulatory relationship between their acidity/alkalinity and catalytic pyrolysis. The study found that acid sites could promote the olefin conversion and adjust the cracking pathway. Furthermore, the densities of strong B acid sites and base sites could regulate olefin adsorption, affecting hydrogen transfer activity. Acid strength was crucial in controlling the aromatization reaction. It showed that thermal cracking played a minor role in catalytic pyrolysis, with methane generation mainly resulting from acid sites promoting the cracking of terminal C–C bonds. Loading phosphorus strengthens the acidity of ZSM-5, while loading cerium weakens its acidity and enhances its alkalinity. By optimizing the acidity and alkalinity of ZSM-5, side reactions were suppressed, maximizing the selectivity of light olefins. The results showed that the light olefin selectivity of Ce–P-ZSM-5 increased from 33.2% to over 80%, while the side reaction selectivity decreased from over 60% to below 10%. This work will lay a good foundation for developing catalysts for catalytic pyrolysis of olefins to produce light olefins.
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JOURNAL OF MATERIALS SCIENCE
·
2024
·Vol. 59
·期 35
·16486-16500
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IF 3.5
Jiao Chuyu,Jiao Qirui,Zhang Wei,Ji Zhuo,Zheng Jiajun,Dai Weijiong,Wang Yan,Pan Meng,Li Ruifeng
Introduction of mesopore system into zeolite crystals is always deemed to be an effective strategy to improve diffusion and acidic accessibility. In this work, a hierarchically structured ZSM-5 with an ultra-small intracrystalline mesopore structure was prepared by using lysine as a pore-forming agent via a hydrothermal crystallization procedure. The structured and textured properties of the as-synthesized samples were characterized by XRD, SEM, EDS, TEM, NH 3 -TPD, FT-IR and N 2 adsorption–desorption isothermals. The results showed that a purely-phased hierarchical ZSM-5 zeolite with a size of 2–6 nm mesopore can be obtained under the condition of lysine/Al 2 O 3 = 2–8. The addition of lysine in the precursor not only generated an ultra-small mesopore system, but also had a significant effect on the acidity of the synthesized sample: With the increased amount of added lysine, the acid density and acid strength of the as-prepared zeolite catalyst were gradually weakened. The effects of the introduced hierarchical pore structure and the tailored acid sites on the catalytic performance of the catalysts were investigated during methanol dehydration to hydrocarbons reaction. The introduced hierarchical pores and the weakened strong acids significantly improved the stability of the catalyst. Meanwhile, the reduced acid density strongly inhibited hydrogen transfer of light olefins intermediate and then increased the selectivity toward light olefins on the hierarchical zeolite catalysts. Graphical abstract To overcome phase separation resulted from brittle combining forces between template and zeolite precursor, lysine, which is easily soluble in water and has a stable structure in the temperature range of ZSM-5 synthesis, served as a mesoporous template, and then, a hierarchical ZSM-5 zeolite was prepared in a hydrothermal method.
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