NEW JOURNAL OF CHEMISTRY
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2021
·Vol. 45
·期 9
·4236-4245
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IF 3.591
Jia Zhang,Jian Yang,Junying Tian,Hailong Liu,Xuemei Li,Weiguo Fang,Xun Hu,Chungu Xia,Jing Chen,Zhiwei Huang
The synthesis of useful amines from bio-based carbonyl compounds is highly desired owing to their mild reaction conditions and green sustainability. The reductive amination of bio-furfural-derived 2-hydroxytetrahydropyran (2-HTHP) to high-value-added 5-Amino-1-pentanol (5-AP) was carried out over efficient Ni–Al2O3 catalysts prepared by a co-precipitation method. Among the Ni–Al2O3 catalysts with different Ni loadings (0–100 wt%) tested, the 50Ni–Al2O3 catalyst exhibited the highest 5-AP yield of 91.3% under mild conditions of 60 °C and 2 MPa H2. This catalyst also presented good stability during a 150 h time-on-stream without appreciable deactivation. Characterization results showed that the 50Ni–Al2O3 catalyst exhibited small Ni0 nanoparticles (5.5 nm), a high reduction degree (up to 95%), and a large amount of strong Lewis acid sites. The cooperative catalysis of the strong Lewis acid sites and highly dispersed metallic Ni sites is suggested to play an important role in achieving high efficiency in 2-HTHP reductive amination.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Zhijun Guo,Guoliang Zhang,Lei Wang,Ping Li,Chunshan Li
To meet the increasing demand for methyl methacrylate, a series of Fe modified Cs–P/γ-Al2O3 catalysts were developed through the impregnation method and tested for the aldol condensation of methyl propionate with formaldehyde in a fixed-bed reactor. Through various characterization studies, the physicochemical properties of the catalysts were systematically studied, especially the relationship between the number of the acid sites and catalytic activity. The number of medium acid sites was increased effectively by the addition of Fe, and the catalytic selectivity was improved consequently. Moreover, the reaction conditions were also optimized, and the life span of the optimized catalyst was evaluated. The Cs–P–0.1Fe/γ-Al2O3 showed excellent reusability during a 260 h lifetime experiment.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Liying Zeng,Yizhou Wang,Jun Mou,Fei Liu,Chunliang Yang,Tianxiang Zhao,Xiaodan Wang,Jianxin Cao
γ-Al 2 O 3 was composited with ZSM-5 molecular sieve to improve its catalytic performance and hydrothermal stability during the conversion of crude methanol into dimethyl ether (DME). When prepared by a liquid-phase coating chemical compounding, the ZSM-5/γ-Al 2 O 3 composite catalyst reached an excellent methanol conversion of 91.9% and DME selectivity of 100%. The DME yield was increased by about 13% compared to only using γ-Al 2 O 3 . Partial desiliconization and dealumination of the ZSM-5 molecular sieve effectively reduced the surface acid center strength and increased the mesoporous ratio. The special composite phase interface effectively decreased surface charge density of γ-Al 2 O 3 and formed the B (Brønsted) - L (Lewis) synergistic active centers. All these factors contribute to improving the catalytic performance, hydrothermal stability and resistance to deactivation of ZSM-5/γ-Al 2 O 3 during the conversion of crude methanol to DME.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2020
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IF 4.65
Guolin Cao,Zhuomin Jin,Jie Zhu,Yunjiao Li,Bin Xu,Yike Xiong,Jiachao Yang
Poor cycling and rate performance are considered one of the greatest obstacles to the large-scale commercialisation of Ni-rich layered cathode material , especially at high cut-off voltages. In this study, we successfully prepared amorphous Al 2 O 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode material by the straightforward carboxymethyl cellulose (CMC)-assisted wet chemical method . As the cathode material for lithium-ion batteries, the amorphous Al 2 O 3 -coated NCM523 maintains capacity retention of 86.30% in the range of 3.0–4.6 V after 100 cycles at 1C and 86.57% at 8C after 50 cycles, which is higher than that of pristine NCM523 under the same conditions (76.40% and 63.20%, respectively). The uniform Al 2 O 3 coating layer greatly inhibits transition metal dissolution on the surface of NCM523 cathode materials at high cut-off voltage. In addition, the structural damage of the NCM523 cathode is effectively retarded due to the consumption of HF by Al 2 O 3 . This work will provide inspiration for the design of new methods for the commercialisation of Ni-rich layered cathode material.
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
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2020
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IF 4.652
Yongchao Shan,Bowen Pu,Enzuo Liu,Chunsheng Shi,Chunnian He,Naiqin Zhao
For nanocarbon reinforced aluminum matrix composites (AMCs), the architecture design of reinforcements is an effective route to obtain superior mechanical performances. In this work, a novel AMC reinforced by CNTs wrapped with γ-Al 2 O 3 (CNTs@Al 2 O 3 ) reinforcement with balanced strength and toughness was fabricated by powder metallurgy methods. The wrapping structure of γ-Al 2 O 3 was synthesized through the in-situ reactions of Al matrix and boric acid decorated CNTs, thus improving the interface coupling of the composite. The CNTs@Al 2 O 3 /Al composite with the addition of 0.5 wt% CNTs and 10 wt% in-situ Al 2 O 3 exhibited a mean ultimate tensile strength of 404 MPa, which is significantly higher than unreinforced pure Al (183 MPa) and those reinforced by individual CNTs (207 MPa) or Al 2 O 3 (289 MPa). An improvement of ductility was also achieved in CNTs@Al 2 O 3 /Al composites compared with the Al 2 O 3 /Al composites with the same Al 2 O 3 content. The synergistic strengthening and toughening effects are ascribed to the ingenious in-situ CNTs@Al 2 O 3 wrapped structure, which highlights the importance of architecture design of reinforcements in AMCs, and sheds new light on the development of CNT-reinforced AMCs.
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MATERIALS CHEMISTRY AND PHYSICS
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2020
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IF 3.408
Yu Chen,Jin Guo,Minyi Lu,Bo Liang
A novel Ni–Fe nanosheets catalyst supported on α-Al 2 O 3 foam ceramic was synthesized by a hydrothermal method and used to obtain multi-walled carbon nanotubes (MWNTs) via the propane partial oxidation . Catalytic performance tests were carried out at 600 °C and atmospheric pressure using a fixed-bed reactor. The synthesized catalysts and carbon materials were analyzed using various characterization methods. According to the field emission scanning electron microscope (FESEM) results, the catalyst morphology was a 3D grid structure consisting of nanosheets 800 nm length and 80 nm width. Additionally, the quantity and quality of the carbon nanotubes were greatly influenced by different oxygen-to-propane molar ratios, defined as the equivalence ratio ϕ (ϕ = 1.5, 1.78, 2). Transmission electron microscope (TEM) images showed that carbon nanotubes over all catalysts were MWNTs. In addition, the thermogravimetric analysis and Raman data showed that a high yield of MWNTs was obtained at ϕ = 1.78, but the accumulated MWNTs at ϕ = 1.5 exhibited a higher degree of graphitization (I D /I G = 0.89) compared with the other two equivalence ratios.
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ChemistrySelect
·
2019
·Vol. 4
·期 43
·12479-12490
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IF 1.716
Guoming Zhao,Enyuan Gao,Qiaoqiao Wan,Qing Liu,Junjie Liang,Yingyun Qiao,Guangzhen Zhao,Yuanyu Tian
Graphical The efficient aerobic oxidative esterification reaction of 1,3-propanediol and methanol to form methyl 3-hydroxypropionate in the presence of 1.5 wt. % Au/Al 2 O 3 catalysts prepared using the deposition-precipitation or colloid-deposition method were investigated. Preparation methods and calcination temperature of catalyst played important role in improving the catalytic activity in this work. 1.5 wt. % Au/Al 2 O 3 catalysts were prepared using the deposition-precipitation or colloid-deposition method and calcined at different temperatures for the selective oxidative esterification reaction of 1,3-propanediol and methanol to form methyl 3-hydroxypropionate (3-HPM). The catalysts were characterized by nitrogen adsorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectra (XPS), CO 2 temperature-programmed desorption (CO 2 -TPD) and NH 3 temperature-programmed desorption (NH 3 -TPD). The effect of the calcination temperature of the catalyst prepared by the deposition-precipitation method on the catalytic performance for the selective oxidative esterification of 1,3-propanediol was studied. The results showed that the conversion of 1,3-propanediol and the selectivity of 3-HPM increased at first and then decreased with the increase of the calcination temperature of catalyst. The highest conversion of 1,3-propanediol and selectivity of 3-HPM at the optimal calcination temperature of 350 °C were 92.0% and 88.5%, respectively. Considering the effects of preparation method and calcination temperature, it could be concluded that the metallic Au nanoparticles with appropriate particle size in coordination with the suitable amount of weak and middle acid and base sites, were favorable to the oxidative esterification of 1,3-propanediol and methanol to 3-HPM. Moreover, we found that the 1.5 wt. % Au/Al 2 O 3 catalyst could be effectively recovered without obvious decline of the catalytic properties.
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ENERGY CONVERSION AND MANAGEMENT
·
2019
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IF 7.181
Yujiao Zhang,Shengli Niu,Chunmei Lu,Zhiqiang Gong,Xun Hu
This research focused on the novel, low-cost and green NaAlO 2 /γ-Al 2 O 3 heterogeneous nanocatalyst, which exhibited the excellent performance in catalyzing transesterification of palm oil with methanol for the biodiesel production. The physicochemical properties of the catalysts were characterized by different methods of the X-ray diffraction (XRD), N 2 adsorption–desorption, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Hammett indicators, field emission scanning electron microscopy-energy dispersive spectrometer (FESEM-EDS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The transesterification parameters, such as the methanol to oil molar ratio, catalyst content and reaction temperature, were optimized using the central composite design (CCD) based the response surface methodology (RSM), where the maximum biodiesel yield of 97.65% was achieved at the methanol to oil molar ratio of 20.79:1, catalyst content of 10.89 wt% and reaction temperature of 64.72 °C. The biodiesel yield was dropped to 52.16% for the third reused cycle due to the leaching of the active sites into the liquid phase. However, the spent catalyst could be effectively regenerated with a small number of active sites and the regenerated catalyst maintained the biodiesel yield of 93.29% for the sixth reused cycle. The properties of the produced biodiesel were in accordance with the ASTM D 6751 standard. Also, the biodiesel production process was environmental friendly based on the green chemistry metrics.
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Catalysts
·
2019
·Vol. 9
·期 10
·849
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IF 3.444
Zeyu Xue,Zhaoping Zhong,Bo Zhang,Chao Xu
To investigate the catalytic pyrolysis performance of complex metal oxide catalysts for biomass, γ-Al2O3was prepared through the precipitation method, and then ZrO2and γ-Al2O3were blended in the proportion of 2:8 using the co-precipitation method. Next, CeO2was loaded on the surface of the catalyst for further modification. The three catalysts, A, ZA and CZA, were obtained. The specific surface and acidity of the catalysts were characterized by nitrogen adsorption–desorption and NH3-Temperature Programmed Desorption (NH3-TPD) respectively. The catalytic pyrolysis performance of catalysts for bamboo residues was investigated by Pyrolysis gas chromatography mass spectrometry (Py-GC/MS). Chromatograms were analyzed for identification of the pyrolysis products and the relative amounts of each component were calculated. Experimental results indicated that catalyst A had a good catalytic activity for the fast pyrolysis of bamboo residues. The addition of ZrO2and CeO2could continuously enhance the acidity of the catalyst and further promote the pyrolysis of macromolecular compounds and deoxidation of oxygen-containing compounds. Finally, catalyst CZA, obtained by compound modification, could not only dramatically reduce the relative content of phenol, acid and aldehyde and other oxygen-containing compounds, but also achieved the maximum hydrocarbon yield of 23.38%. The catalytic performance of catalyst CZA improved significantly compared with catalyst A.Keywords:biomass;pyrolysis;catalytic cracking;Py-GC/MS;complex metal oxides
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CHEMICAL ENGINEERING JOURNAL
·
2026
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IF 12.5
Weizhen Zhang,Wenqian He,Qian Yan,Lele Zhang,Nan Ni,Shaorui Song,Shuhua Tu,Jie Feng
Surfactant-free interfacial synthesis of hollow Al 2 O 3 via kinetic modulation • Chelation enables precursor transition from hydrophobic to amphiphilic states. • Simple room-temperature strategy bypasses harsh energy-intensive methods. • PDRC coatings deliver 97.6% solar reflectance and 0.976 mid-IR emissivity. • The scalable coatings realize a remarkable sub-ambient cooling of 9.66 °C. Hollow γ-Al 2 O 3 architectures are highly attractive for passive daytime radiative cooling (PDRC) owing to their low density and unique optical characteristics. However, their fabrication typically relies on sacrificial templates, hydrothermal treatments, or high-temperature processing, while the intrinsically ultrafast hydrolysis of aluminum alkoxides has long prevented their use in hollow-structure engineering. Here, we report a surfactant-free, chelation-enabled interfacial synthesis strategy that overcomes this limitation through kinetic regulation of aluminum sec-butoxide. The coordination process gradually transforms the precursor from hydrophobic to amphiphilic, enabling spontaneous self-emulsification and controlled interfacial assembly. As a result, hierarchical hollow γ-AlO(OH) microspheres are obtained at room temperature and subsequently converted into hollow γ-Al 2 O 3 microspheres by calcination. The resulting hollow γ-Al 2 O 3 microspheres exhibit tunable diameters (3.3–15.8 μm), uniform nanoscale shells (162 ± 60 nm), and an ultralow density of 0.083 g·cm −3 . The process is readily scalable using an industrial homogenizer. When incorporated into coatings, the hollow microspheres provide abundant dielectric interfaces that enhance solar reflection and thermal emission, delivering a solar reflectance of 97.6%, an atmospheric window emissivity of 0.976, and a sub-ambient cooling of 9.66 °C under a solar irradiance of 454.5 W·m −2 . This work provides a scalable and energy-efficient manufacturing strategy for hollow γ-Al 2 O 3 architectures, offering significant potential for large-area radiative cooling coatings and thermal management applications. Download: Download high-res image (108KB) Download: Download full-size image
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Processes
·
2023
·Vol. 11
·期 11
·3181
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IF 3.5
Chuangchuang Yang,Qiaoling Dai,Anpeng Hu,Hui Yuan,Qinghe Yang
In this present work, a new kind of sulfurized hydrodesulfurization catalyst was synthesized via the hydrothermal treatment of MoS2, NiCO3·2Ni(OH)2·4H2O, and Al2O3precursors, followed by annealing under a H2atmosphere, which does not require a sulfurization process compared to traditional preparation methods. The influence of the annealing temperature and the type of Al2O3precursor on the interactions between MoS2and Al2O3were studied using X-ray fluorescence spectroscopy, X-ray diffraction, N2adsorption–desorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results indicated an increase in the number of stacked layers of the MoS2catalyst, accompanied by a decrease in the degree of decoration of Ni atoms onto MoS2nanoslabs, as a result of the strengthened MoS2–Al2O3interaction. Subsequently, the efficiency of hydrodesulfurization (HDS) was evaluated using dibenzothiophene as a representative reactant, while establishing a correlation between the structure of the catalyst and its performance. The catalysts, using pseudo-boehmite as the precursor and calcined at 500 °C, synthesized by calcining pseudo-boehmite as the precursor for Al2O3at a temperature of 500 °C and possessing suitable metal–support interactions, exhibited a reduced number of MoS2stacking layers and lateral dimensions, along with an optimal decoration degree of Ni atoms, thereby resulting in the highest level of HDS activity.
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Thermal Science and Engineering Progress
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2023
·
IF 4.8
Jing Yi,Pan Wang,Feixiang Li,Qi Chen,Lili Lei
Catalytic combustion of C 2 H 6 at equivalence ratios of 1.0 and 1.4 over non-thermal plasma (NTP) modified Pd/Al 2 O 3 was studied experimentally to examine the effect of O 2 and N 2 plasma on the catalyst activity and physico-chemical property. C 2 H 6 conversion, chemical product distribution and selectivity were taken into account to evaluate the performance of modified catalysts in C 2 H 6 oxidation at 200–500 ℃. The results showed that the plasma modification had suppressive effects on the activity of Pd/Al 2 O 3 . When compared to Pd/Al 2 O 3 , T 30 for the modified Pd/Al 2 O 3 were shifted to higher temperatures by approximately 30–50 ℃. For catalysts modified by plasma, significantly more CO was formed in the C 2 H 6 combustion at high temperature region. Moreover, the structure, morphology and chemical states of Pd/Al 2 O 3 after modification were thoroughly analyzed with the means of N 2 adsorption–desorption, XRD, XPS and SEM. The surface area of modified catalysts decreased, resulting in the activity degradation. The leaching of Pd species and transform of γ-Al 2 O 3 to θ-Al 2 O 3 were observed after the NTP treatment with highly energetic electrons. It should to be highlighted that the reduction of Pd 2+ to Pd 0 by NTP modification on the catalyst surface from XPS analysis. The NTP had the potential to reduce catalysts while employing oxidizing or inert gases.
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