SURFACE & COATINGS TECHNOLOGY
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2022
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IF 4.865
Juan Du,Zhaolin Wang,Ziming Wei,Jiawei Yao,Haipeng Song
This paper investigated the preparation of new environmental, pH stimulation response nanocontainer enhanced, self-healing, and efficient anti-corrosion coating for aluminum alloy protection. Silane/Ce-ZSM-5 coating with improved morphology was successfully synthesized on aluminum alloy surface, through the new proposed “hydrothermal crystallization - ion exchange - self-assembled seed growth - hot pressing” technology, in which ZSM-5 molecular sieve was served as pH stimulation response nanocontainer. The corrosion resistance and self-healing ability of the coating in 3.5 wt% NaCl solution were further investigated by the combined analysis of SEM, EIS, LEIS , ICP-MS characterization and 3D microscopic observation. The experimental results showed that the prepared silane-Ce-ZSM-5 coatings exhibited excellent corrosion protection and self-healing ability, which was attributed to the pH stimulation release of corrosion inhibitor Ce 3+ when the coatings were damaged. The ZSM-5 zeolites generated Ce(OH) 3 or CeO 2 precipitates to gradually fill the aluminum alloy defects, thus forming a dense protective layer and inhibiting the corrosion activity.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Yubo Pan,Yali Zhang,Yaoguo Huang,Yun Jia,Linlin Chen
Cyanide wastewater contains highly toxic contaminants such as free cyanide and metal-cyanide complex, it is necessary to find the appropriate degradation technologies. In this study, a simple and effective photocatalyst with enhanced adsorption and photocatalytic activity was developed. A new composite photocatalyst was successfully prepared by solid-state dispersion (SSD) method, which combined graphene oxide (GO), nano titanium dioxide (nano-TiO 2 ) and silicon-based zeolite (ZSM-5). The techniques of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N 2 adsorption–desorption test, X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) were used to characterize the samples. The experiments with different content of nano-TiO 2 , different wavelengths of light source, different catalyst dosage, control experiments of different materials, and the determination of pH value and zeta potential were also carried out. The results showed that the 3.0 g/L of GTZ-60 (GO/TiO 2 /ZSM-5 composite photocatalyst with a content of 60 wt% TiO 2 ) has the highest photocatalytic degradation efficiency under ultraviolet wavelength which the degradation efficiency of total cyanide and copper could reach 98.73% and 98.96%, respectively. The degradation of total cyanide followed the pseudo-first-order kinetics. The photoelectric properties of GTZ-60 obviously improved the migration and separation of photogenerated electrons ( e − ) and holes ( h + ), so that high photocatalytic efficiency was obtained. XPS analysis showed that cyanide was finally degraded to carbon oxide and nitrogen oxide. Copper and zinc are removed in the form of copper (Ⅱ) and zinc (Ⅱ).
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CRYSTENGCOMM
·
2021
·Vol. 23
·期 15
·2793-2800
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IF 3.545
Xueshuai Chen,Rongli Jiang,Yu Gao,Zihan Zhou,Xingwen Wang
In this work, nano-ZSM-5 zeolite with superior catalytic properties was synthesized from LAPONITE® as one of the Si sources by a dry gel conversion (DGC) method, and its crystallization mechanism was investigated as well. The properties of ZSM-5(Z-L) synthesized from LAPONITE® as one of the Si sources and ZSM-5(Z-T) synthesized from tetraethylorthosilicate (TEOS) as a single Si source have been compared. The results show that LAPONITE® is an important factor for the formation of nanocrystals with high crystallinity. It can not only act as the Mg and Si source for the zeolite synthesis but also exert a “confined space” effect to control ZSM-5 crystal growth. The Z-L sample with nanosized crystals can shorten the reactant and product diffusion path length, which seriously improves diffusion efficiency and results in longer catalytic stability. This work provides a novel and efficient route for synthesis of nano-ZSM-5 zeolite.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
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IF 3.764
Hailin Zhao,Bingjing Tang,Jie Tang,Yafeng Cai,Yao Cui,Hao Liu,Li Wang,Yunsong Wang,Wangcheng Zhan,Yanglong Guo,Yun Guo
Catalytic oxidation is believed to be the most efficient method for indoor formaldehyde purification. Herein, we reported that the Pt/Na-ZSM-5 catalyst with low Pt loading (0.16 wt %) prepared by depositing Pt on Na+ ion-exchanged ZSM-5 could completely oxidize 300 ppm formaldehyde in 2.5 vol % H2O at 32 °C and maintain its activity during the 62 h-long stability test. Multiple characterizations revealed that the presence of Na species significantly enhanced formaldehyde adsorption ability and made Pt species tend to exist in the form of metal Pt through electron transfer from Na to Pt, which promoted the activation of oxygen and opened a new efficient formaldehyde oxidation pathway, namely, direct decomposition of formate. The synergistic effects resulted in the TOF of Pt(0.16)/Na-ZSM-5 being about nine times higher than that of Pt(0.50)/ZSM-5. Our study showed that utilizing an alkali metal to tune the surface acidity/basicity of the support and the state of the supported noble metal was a promising way to improve the intrinsic catalytic performance and reduce noble metal usage.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2020
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IF 2.627
Xianfeng Liu,Fu Yang,Shuying Gao,Bo Shao,Shijian Zhou,Yan Kong
Design and synthesis of low cost and efficacious industrial catalyst for the oxidation of styrene has been an important research project. Herein, ZSM-5 zeolite containing tetrahedral vanadium (V) and Brønsted acid sites (V-H-ZSM-5) was prepared, and identified by characterizations such as XRD, SEM, UV–vis, NH 3 -TPD, H 2 -TPR N 2 -adsorption/desorption and FTIR. V-H-ZSM-5 performed extremely enhanced catalytic activity for the oxidation of styrene with 30% H 2 O 2 at 40 °C. Moreover, in-situ FTIR spectrum was used to investigate the catalytic mechanism. The results demonstrate that Brønsted acid site could not only increase the adsorption concentration of styrene in the micropores of V-H-ZSM-5 via the π complex interaction between double bond of styrene and Brønsted acid sites, but also increase the oxidation potential of H 2 O 2 . The synergetic action of tetrahedral vanadium (V) and Brønsted acid enhanced the catalytic activity for the oxidation of styrene with 30% H 2 O 2 . Impressively, V-H-ZSM-5 performed high reusability within five runs at a low reaction temperature (40 °C) for the first time.
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RSC Advances
·
2020
·Vol. 10
·期 37
·22126-22136
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IF 3.119
Hongchang Yu,Fuwei Li,Wen He,Caifeng Song,Yansong Zhang,Zhixia Li,Hongfei Lin
Micro–mesoporous ZSM-5 with different Si/Al ratios (MZ-X, X = 27, 80, 150) were synthesized by adding microcrystalline cellulose (MCC) as co-template into the hydrothermal synthesis process of zeolites. The resultant ZSM-5 were used for catalytic cracking of high density polyethylene (HPDE) and polypropylene. It was found that introduction of MCC significantly enhanced the formation of mesopores and strong acid sites. MZ-27 achieved the highest oil yield: 21.5% for HPDE and 32.1% for polypropylene, and the light aromatics (BTEX) selectivity therein were 87.6% and 79.7%, respectively. HZ-150 (MCC-free ZSM-5, Si/Al = 150) achieved the highest gas yield: 85.4% for HDPE and 76.7% for polypropylene, and the light olefins (C2–4) selectivity therein were 44% and 48.3%, respectively. The dense acidic sites and mesoporous structure of MZ-27 were responsible for its better activity for producing aromatic products. The moderate acidity and microporous structure of HZ-150 were helpful for producing light olefins from catalytic cracking of polyolefin plastics.
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 24
·7034-7044
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IF 5.726
Liwei Zhang,Huaike Zhang,Zhiqiang Chen,Qiang Ning,Suyao Liu,Jie Ren,Xiaodong Wen,Yong-Wang Li
To correlate the relationship between the Al distribution and the catalytic performance of long-chain olefin aromatization, several ZSM-5 zeolites with different Al locations and proximities were prepared via adjusting the hydrothermal synthesis conditions. Characterization by XRD, SEM and N2-adsorption indicated that all the as-prepared ZSM-5 zeolites exhibited high crystallinities, uniform morphologies and open channels. However, a great difference in the framework Al (AlF) positions was observed by 27Al MAS NMR and UV-vis-DRS of Co(II) ions, thus leading to the distinct acidity of various zeolites as determined by NH3-TPD and Py-IR. In 1-octene aromatization reaction, ZSM-5 catalysts exhibited significantly different catalytic performances and reaction pathways, which were closely related to the types and locations of the AlF atoms. The ZSM-5 zeolite catalyst with the most abundant single Al sites exhibited the lowest aromatics selectivity, while Al pairs in the framework were more favorable to the formation of aromatics. Moreover, the product distribution revealed that the Al pairs in the channel intersections of the ZSM-5 zeolite were responsible for the improved selectivity to heavy aromatics due to the fewer space restrictions; however, the Al pairs in the sinusoidal and straight channels with severe size restrictions suppressed the generation of bigger aromatics on the Al sites. This result provided a new potential method for precisely tailoring the catalytic selectivity in olefin conversion and upgrading the Fischer–Tropsch oil.
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Journal of Central South University
·
2020
·Vol. 26
·期 11
·2974-2986
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IF 1.249
Xu Si-quan,Pan Dong-hui,Xiao Guo-min
With the aim of achieving a high 5-hydroxymethylfurfural (HMF) yield from glucose with H-ZSM-5 catalyst at low cost, three inexpensive biphasic reaction systems, H 2 O—tetrahydrofuran (THF), H 2 O—2-methyltetrahydrofuran (MeTHF) and H 2 O’2-butanol, were discovered and proved to be particularly effective in promoting the formation of HMF from glucose over H-ZSM-5 zeolite. In order to determine the optimal process conditions, the effects of various experimental variables, such as reaction temperature, reaction time, catalyst dosage, volume of organic solvent, as well as inorganic salt type on glucose conversion to HMF in three systems were investigated in detail. It was found that under optimal reaction conditions, H 2 O—THF, H 2 O—2-butanol and H 2 O—MeTHF allowed the glucose dehydration process to achieve HMF yields of up to 61%, 59%, and 50%, respectively. Moreover, in the three biphasic systems, the H-ZSM-5 catalyst was also demonstrated to maintain excellent stability. Thus, the catalytic approach proposed in this paper can be believed to have potential prospects for industrially efficient and low-cost production of HMF.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Yixuan Zheng,Weiwei Ning,Quanhua Wang,Xueling Wei,Xingyang Li,Meng Pan
Hierarchical ZSM-5 was successfully prepared using l -carnitine and l -lysine as mesoporous templates, and the influence of the dosage of “secondary template” represented by l -carnitine on the formation of hierarchical zeolite was investigated in detail. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption, nuclear magnetic resonance (NMR), thermogravimetric-derivative thermogravimetry (TG-DTG), pyridine infrared and temperature programmed desorption of ammonia (NH 3 -TPD) were used to characterize the structural and textural properties of the as-prepared samples. The results showed that the hydrophilic property of the amino acid template overcame the phase separation and constructed a mesoporous system with an ultra-small size of 2–10 nm in the as-synthesized zeolite crystals. Not only the morphology and grain size, but also the Si/Al ratio and then the acidity of zeolite were affected by the “secondary template”. Catalytic cracking of triisopropylbenzene was chosen as a probe reaction so as to investigate the effect of the fabricated hierarchical porous system on the catalytic performances of the catalysts. The results showed that the introduction of hierarchical pores elevated the external surfaces of the catalyst and therefore significantly improved the catalytic cracking performance of the catalyst for the heavy molecules triisopropylbenzene. At the same time, the introduced mesopore structure also gave the macromolecule reactant a hierarchically cracking process because of the acid active sites located in the different spaces.
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Yifan Wu,Guangbing Liang,Xinna Zhao,Hui Wang,Zhenping Qu
It is feasible and profitable to figure out multidiscipline environmental issues synergistically. Coal fly ash based adsorbent materials are widely used in the emission control of volatile organic compounds. A solvent-free method which was more environmental-friendly for ZSM-5 zeolites synthesis from coal fly ash was proposed to eliminate toluene. The results indicated that ZSM-5 zeolites were successfully synthesized from the precursor gel of coal fly ash with 30–60 wt% moisture contents. The SiO 2 /Al 2 O 3 mole ratio of gel was up to 99 after the pretreatment of alkali roasting and acid precipitation. During the synthesis process, the appropriate Na 2 CO 3 -to-SiO 2 ratio was 0.3, and the mesoporous formation would be facilitated along with the moisture content of gel. On the tendency of adsorption testing, the microporous structure was prone to the toluene adsorption, and the desorption was dependent on the mesoporous structure. The maximum adsorption capacity of 75.1 mg·g −1 was observed on S-40 sample, and the minimum desorption activation energy of 39.97 kJ·mol −1 was found on S-60 sample. The humid condition can reduce the toluene adsorption performance, and the maximum adsorption capacity was down to 63.7 mg·g −1 . Additionally, the synthetic ZSM-5 zeolites still have some superiority in economics and ecology when compared with commercial zeolites. The novel synthesis method, preparing controllable ZSM-5 zeolites from coal fly ash with the advantages of low cost and environmental friendliness, exhibited the tremendous application potential in environmental field.
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CHEMOSPHERE
·
2019
·
IF 5.108
Rongji Cui,Suxia Ma,Jie Wang,Shujun Sun
The catalytic gas-phase H 2 O 2 oxidation of NO was achieved over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5. ESR tests illustrate that the three catalysts can catalyze decomposition of H 2 O 2 yielding highly reactive hydroxyl radicals , of which Fe/K10 has the fastest rate, followed by Fe/γ-alumina. Fe 3+ in Fe/K10 and Fe/γ-alumina show lower density of electron cloud due to a strong interaction between Fe 3+ and the support, which benefits the electron transfer from the H 2 O 2 to Fe 3+ , thus favoring the production of hydroxyl radicals. Fe species exist on the surface of Fe/K10 mainly in the form of Fe 2 O 3 , whereas Fe species of Fe/γ-alumina and Fe/ZSM-5 exist mainly in the form of Fe 3 O 4 , and it is found that Fe 2 O 3 is more active than Fe 3 O 4 in catalytic gas-phase H 2 O 2 oxidation of NO. Interestingly, Fe/ZSM-5 has the lowest efficiency in generating hydroxyl radicals, its NO removal efficiency is 90%, which is much higher than 47.5% for Fe/γ-alumina and 62.3% for Fe/K10. In-situ IR results suggested that Fe/ZSM-5 are dual functional in oxidation of NO, that is, whether both Fe ion sites and Brønsted acid sites collectively provide the catalytic functionality. In the meantime, a possible reaction mechanism on catalytic gas-phase H 2 O 2 oxidation of NO over Brønsted acid sites is proposed.
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高影响因子
JOURNAL OF POROUS MATERIALS
·
2024
·
IF 2.5
Zhang Yanting
Both seed solution and Cetyltrimethylammonium bromide(CTAB) serve as common template agents in the synthesis of hierarchical ZSM-5 zeolites. However, their specific roles in the synthesis process have not been clearly understood. In this study, hierarchical ZSM-5 zeolites were successfully synthesized using a 1.5% mass fraction (relative to the silicon source) seed solution in combination with varying amounts of CTAB. The physical and chemical properties of the hierarchical ZSM-5 zeolites were characterized using X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature N 2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), ammonia temperature-programmed desorption (NH 3 -TPD), pyridine-IR, and 2,4,6-collidine-IR. The investigation revealed that the CTAB content significantly influenced the synthesis of hierarchical ZSM-5 zeolites, with CTAB contributing to framework filling, charge balancing, and acting as a mesoporous template during the synthesis process, while the seed solution primarily served as a structure-directing agent. Moreover, utilizing the conversion of C8 aromatic hydrocarbons as a probe reaction, it was demonstrated that ZSM-5 zeolites synthesized with the co-assistance of seeds and CTAB exhibited enhanced conversion for ethylbenzene and m-xylene compared to samples synthesized exclusively with a seed solution.
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