CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Mithun Nath,Shengqiang Song,Hang Liu,Yawei Li
Despite huge potential, Al 2 O 3 –CaO–Cr 2 O 3 system has been one of the least investigated one due to the generation of carcinogenic and toxic Cr(VI) compounds. Herein, we investigated the system under air atmosphere varying Cr 2 O 3 while keeping Al 2 O 3 :CaO ratio constant in order to identify the Cr(VI) dominant region, eventually to avoid it. The Ca 4 Al 6 Cr VI O 16 phase predominantly formed in the air atmosphere with Cr 2 O 3 content up to ∼12 mol%. However, an unprecedented Cr(III) phase appeared under air at higher Cr 2 O 3 content (26.43 mol%). We then synthesized the new polycrystalline ternary Cr(III) compound (CaAl 2 Cr 2 O 7 ) at 1500 °C under air atmosphere for the first time. A trigonal symmetry of hexagonal crystal family with space group P3 (143), lattice parameters a = b = 7.7909 Å and c = 7.6506 Å were determined from the X-ray powder diffraction pattern study. Electron microscope studies revealed uniform hexagonal microcrystals with similar lattice parameters. Most significantly, the binding energies of 586.1 and 576.2 eV for Cr2p 1/2 and Cr2p 3/2 respectively implied the +3 oxidation state of Cr in this compound.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Chi Ma,Meng-Jun Su,Yong Luo,Guang-Wen Chu,Bao-Chang Sun,Jian-Feng Chen
An Al2O3-coated stainless steel wire mesh packing was prepared, aiming to serve as the monolithic catalyst support applied in a rotating packed bed (RPB) reactor. Before the application, the wetting behavior and gas–liquid mass transfer performance of Al2O3-coated wire mesh packing were investigated in this work. The results showed that the Al2O3-coated stainless steel fiber had on average 18.8% longer liquid spreading length compared with the uncoated stainless steel fiber. The gas–liquid effective interfacial area (ae) and the volumetric liquid-side mass transfer coefficient (kLae) of the RPB with Al2O3-coated wire mesh packing were on average 25.9 and 45.7% higher than those with uncoated wire mesh packing, respectively. The Al2O3-coated wire mesh packing has great prospects for the catalytic reactions in the RPB reactor by providing double functions of mass transfer intensification and the monolithic catalyst support.
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BIORESOURCE TECHNOLOGY
·
2018
·
IF 5.807
Zheng-Zhe Zhang,Ya-Fei Cheng,Lian-Zeng-Ji Xu,Yu-Hui Bai,Jia-Jia Xu,Zhi-Jian Shi,Yang-Yang Shen,Ren-Cun Jin
The increasing use of engineered metal oxide nanoparticles (MONPs) in consumer products raises great concerns about their environmental impacts, but their potential impacts on anaerobic ammonium oxidation (anammox) process in wastewater treatment remain unclear. In this study, the presence of MONPs (1, 50, 200 mg L −1 ) exhibited no visible effects on the nitrogen removal performance of anammox reactors, but high levels (200 mg L −1 ) of SiO 2 NPs, Al 2 O 3 NPs and CeO 2 NPs had a distinct effect on shaping the anammox community. Long-term exposure of MONPs caused different responses in the relative abundance of Ca. Kuenenia , the level of functional gene Hzs A and the activities of three key enzymes involved in anammox metabolism, but no significant inhibition effects on specific anammox activity were detected. Overall, the effects of MONPs on anammox community structure and sludge properties depended on their types and levels and followed the order SiO 2 > CeO 2 > Al 2 O 3 > TiO 2 .
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ChemCatChem
·
2018
·Vol. 10
·期 20
·4689-4698
·
IF 4.674
Yan Liu,Ye Wu,Zarina Akhtamberdinova,Xiaoping Chen,Guodong Jiang,Dong Liu
Graphical High fives ! The catalyst 5Ni-5Ce exhibits the best catalytic performance in the dry reforming of shale gas and CO 2 . The introduction of Ce creates strong interaction between Ni and Ce, which enhances the electron transfer between them. And the substitution of Ni for Ce produces oxygen vacancies and defects, which can accelerate the adsorption and activation of the reactant gases molecule, further promoting the reaction. The dry reforming of shale gas (methane and ethane with an average ratio of 4 : 1) with carbon dioxide (DRS) is considered to be a promising way to produce syngas, which widens the utilization of shale gas and mitigates carbon dioxide emission. In this paper, Ce modified Ni-based catalysts were developed and the corresponding catalytic performances for DRS were investigated with a fixed bed reactor. Results showed that the catalyst containing 5 wt% of Ni and 5 wt% of Ce performed a best catalytic effect, including the selectivity of syngas and the carbon resistance performance, which is due to the good metal dispersion, strong interaction between Ni and Ce, and the formation of Ni-CeO x solid solution. The electron transfer between Ni and Ce, substitution of Ni for Ce, and the sequential oxygen vacancies or defects, play significant roles in activating CH 4 , C 2 H 6 and CO 2 . The conversion of reactant gas increased with temperature, while the selectivity of syngas is little affected with temperature. In addition, the desired catalyst containing 5 wt% of Ni and 5 wt% of Ce showed good stability in the long-time operation, which indicates that the Ce modified Ni-based catalyst is a promising one for the dry reforming of shale gas.
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CHINESE CHEMICAL LETTERS
·
2018
·
IF 2.631
Rongqiao Chen,Chune Guo,Wubo Chu,Nan Jiang,He Li
Marine microorganism accumulated on the surface of ships or pipelines would accelerate fouling organisms, such as mussels and barnacles, adhered on the surface. It was significant to understand the bio-interaction between the microorganisms and the surface. Attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy was used to study the initial stages of marine microorganism adhering to surfaces, because it could probe the microorganism interaction to the surface regardless of the water interference. Bacillus sp. and Escherichia coli were selected to study the initial attachment on different surfaces, because they were typical fouling microorganisms and showed opposite Gram stain results. The assays were conducted respectively in dried and settled bacteria on two different surfaces (ZnSe, Al 2 O 3 coated on ZnSe). IR spectra of settled bacteria showed amide I band red shift and amide II band blue shift in aqueous environment on both surfaces compared with the dry bacteria. The reasons of amide bands shift were investigated and it was discovered that the hydrogen bond between the water and the protein of the bacteria led to the protein secondary structure change. ATR-FTIR provided an approach to study the attachment process and showed dynamic changing process on the surface, and it could be an appropriate approach to study the interaction between proteins and chemicals.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2013
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IF 3.548
Ying Wang,Jun Peng,Chen Zhou,Zi-Yian Lim,Chunzheng Wu,Shuang Ye,Wei Guo Wang
Ni/ x Pr-Al 2 O 3 ( x = 5, 10, 15, 20 wt%) catalysts with an application in autothermal reforming of methane were prepared by sequential impregnation synthesis; its catalytic performance was evaluated and compared with that of Ni/γ-Al 2 O 3 catalyst; the physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-Ray Photoelectron Spectrometer (XPS), Thermo Gravimetric Analyzer (TGA) and H 2 -temperature programmed reduction techniques (TPR). The results showed that Pr addition promoted the reduction of nickel particle size on the surface. TPR experiments suggested a heterogeneous distribution of nickel oxide particles over x Pr-Al 2 O 3 supports and the promotion of NiO reduction by Pr modification. The CH 4 conversion increased with elevating levels of Pr addition from 5% to 10%, then decreased with Pr content from 10% to 20%. For the stability catalytic tests, Ni/ x Pr-Al 2 O 3 catalysts maintained the high activity after 48 h while Ni/Al 2 O 3 had a significant deactivation.
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TheScientificWorldJOURNAL
·
2013
·
IF 1.73
Wei Lin Li,Shuan Bao Tian,Feng Zhu
A simple and efficient synthetic protocol has been developed for the synthesis of 3-substituted-2H-1,4-benzothiazines by using a novel sulfonic acid functionalized nano-γ-Al2O3 catalyst, devoid of corrosive acidic, and basic reagents. The developed method has the advantages of good to excellent yields, short reaction times, operational simplicity, and a recyclable catalyst. The catalyst can be prepared by a simple procedure from inexpensive and readily available nano-γ-Al2O3 and has been shown to be recoverable and reusable up to six cycles without any loss of activity.
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MOLECULES
·
2024
·Vol. 29
·期 12
·2753
·
IF 4.2
Yongzhen Gao,Wenjing Yi,Jingyi Yang,Kai Jiang,Tao Yang,Zhihan Li,Meng Zhang,Zhongyi Liu,Benlai Wu
The selective hydrogenation of the biomass platform molecule furfural (FAL) to produce furfuryl alcohol (FA) is of great significance to alleviate the energy crisis. Cu-based catalysts are the most commonly used catalysts, and their catalytic performance can be optimized by changing the preparation method. This paper emphasized the effect of calcination atmosphere on the performance of a Cu/Al2O3catalyst for the selective hydrogenation of FAL. The precursor of the Cu/Al2O3catalyst prepared by the ammonia evaporation method was treated with different calcination atmospheres (N2and air). On the basis of the combined results from the characterizations using in situ XRD, TEM, N2O titration, H2-TPR and XPS, the Cu/Al2O3catalyst calcined in the N2atmosphere was more favorable for the dispersion and reduction of Cu species and the reduction process could produce more Cu+and Cu0species, which facilitated the selective hydrogenation of FAL to FA. The experimental results showed that the N2calcination atmosphere improved the FAL conversion and FA selectivity, and the FAL conversion was further increased after reduction. Cu/Al2O3-N2-R exhibited the outstanding performance, with a high yield of 99.9% of FA after 2 h at 120 °C and an H2pressure of 1 MPa. This work provides a simple, efficient and economic method to improve the C=O hydrogenation performance of Cu-based catalysts.
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POLYMER COMPOSITES
·
2024
·
IF 4.8
Yingjun Li,Yingchun Lu,Yunpeng Li,Hanwen Duan,Chaoyi Zhu,Yuanlin Zhou
The strategic alignment of nanoplatelets within polymer matrices is pivotal for the development of nanocomposites with superior gas barrier characteristics. In this work, the effect of lamellar particles orientation in polymer for gas permeation was demonstrated. The magnetic α-Al 2 O 3 (Al 2 O 3 @PDA-Fe 3 O 4 ) was first prepared by in situ growth of Fe 3 O 4 nanoparticles immobilized on polydopamine (PDA)-modified Al 2 O 3 surface. Subsequently the orientation of magnetic α-Al 2 O 3 in brominated butyl rubber (BIIR) was achieved by modulating the applied magnetic field direction. Results show that the PDA, as the role of surface adhesive, not only anchored Al 2 O 3 substrate but also bound ferric ions for the further in situ formation of Fe 3 O 4 , which ensured the physico-chemical stability of the magnetic α-Al 2 O 3 . Comparison of hydrogen permeation performance of composites with in-plan, middle-of plane and out-of plane alignment demonstrated the effect of lamellar particles orientation. The Al 2 O 3 @PDA-Fe 3 O 4 /BIIR composite with in-plane alignment had the best hydrogen barrier property by a 50% reduction in hydrogen permeability coefficient compared to the neat BIIR, underscoring the critical role of particle orientation in enhancing the gas barrier properties of nanocomposites. Highlights The structural stability of magnetic Al 2 O 3 nanocomposites was enhanced by polydopamine (PDA). The composites with in-plane alignment, middle-of plane alignment and out-of plane alignment were prepared by a magnetic field. The effect of lamellar particles orientation on gas permeation of polymer nanocomposites was studied. The composites with in-plane alignment possesses the best gas barrier property.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 26
·13544-13556
·
IF 8.867
Yuezhan Feng,Ji Hu,Yang Xue,Chengen He,Xingping Zhou,Xiaolin Xie,Yunsheng Ye,Yiu-Wing Mai
Fire hazards related to polymer-based thermally conductive composites (PTCs) used in electronic equipment are a significant, but often neglected, risk. Here, we offer a solution by incorporating flame retardant-functionalized graphene (PFR-fRGO) into PTCs using a procedure that improves both their flame resistance and thermal conductivity. Briefly, PFR-fRGO was prepared by covalently grafting a polyphosphoramide oligomer (PDMPD) onto the surface of graphene, which was then introduced in situ into epoxy resin/Al2O3 (EP/Al2O3) composites. As expected, the incorporation of PFR-fRGO not only increased the thermal conduction paths by weakening the settlement of microparticles, but also reduced the interfacial thermal resistance by enhancing interfacial interactions, both of which resulted in an enhancement of the thermal conductivity of the ternary composites. The resultant EP/Al2O3/PFR-fRGO composite exhibited a superior flame retarding ability with dramatic decreases being seen in the high peak heat release rate (PHRR), the total heat release (THR) and the total smoke production (TSP), i.e. 53%, 37% and 57%, respectively, when compared to pure epoxy resin. Additionally, a synergistic flame retarding effect was found in the ternary composite compared to the EP/PFR-fRGO and EP/Al2O3 composites. The remarkable enhancement in flame retardancy was mainly attributed to the catalytic charring effect of PFR-fRGO and the template effect of Al2O3, both of which resulted in the formation of a high strength, thermally stable protective layer in the condensed phase that is able to retard the permeation of heat and volatile degradation products during combustion, slow down the heat release rate and protect the underlying polymer.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 14
·6664-6676
·
IF 8.867
Zepei Bao,Lin Ye,Beibei Fang,Lijun Zhao
Herein, Fe0.32Co0.68 binary metal nanoparticles synthesized at room-temperature were loaded onto a novel hierarchical flower-like γ-Al2O3@C composite, which improved the stability and dispersity of the Fe0.32Co0.68 nanoparticles. The freshly prepared Fe0.32Co0.68/γ-Al2O3@C displayed good adsorption of Orange II (100 mg L−1, 973.55 mg g−1). Subsequently, the used Fe0.32Co0.68/γ-Al2O3@C adsorbent (Fe–Co oxide/γ-Al2O3@C) was reused as a peroxymonosulfate (PMS) catalyst. Amazing results were obtained, which demonstrated that Fe–Co oxide/γ-Al2O3@C can highly efficiently decompose Orange II (60 mg L−1, 1 min; 90 mg L−1, 2 min, 120 mg L−1, 7 min and 150 mg L−1, 10 min) as a PMS catalyst. It also exhibited good general degradation of different organic pollutants and excellent reusability (98%, tenth cycle) due to the structural stabilities of γ-Al2O3@C. Further, an experiment was carried out to treat high concentrations of Orange II (200 mg L−1) with the Fe0.32Co0.68/γ-Al2O3@C nanocomposite. After adsorption, PMS was added, and 98% degradation occurred within 5 minutes. The combination of adsorption and PMS advanced oxidation techniques may be one of the effective ways to deal with high-concentration dye wastewater.
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RSC Advances
·
2024
·Vol. 14
·期 52
·39061-39068
·
IF 3.9
Han Xiao,Jiaming Dong,Yimin Zhang,Xiaohua Cao,Yanhong Li,Dedong He,Yongming Luo,Pingyan Wang,Hao Wang
The presence of abundant hydroxyl groups on the surface of Al2O3 can promote the dispersion of Ni species but produce an inactive NiAl2O4 phase at high temperatures. Moreover, the catalysts prepared by the conventional incipient wetness impregnation method lack the sites for the activation of CO2, which leads to coke deposition and thus affects the catalyst activity. The above restricts the utilization of Ni in conventional Ni/Al2O3 catalysts. In this paper, Al2O3 support was pre-treated by acetic acid to selectively remove hydroxyl groups without affecting the coordination environment of Al. Results revealed that the Al2O3 support after hydroxyl removal not only showed moderate metal–support interaction but also produced more sites for the adsorption and activation of the reactant, which significantly improves the utilization of nickel species and the stability of the catalyst. The conversion of CH4 and CO2 at 700 °C was as high as 88% and 90%, respectively, and has an excellent stability of 50 h. This study provides a feasible strategy for the design of highly active methane dry-reforming catalysts.
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