COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
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IF 5.518
Can Wu,Yuyang Hong,Jing Ni,Paul D. Teal,Lidan Yao,Xinglin Li
Grease plays an important role in reducing friction and wear of rolling bearings and improving their service life and reliability. However, increasing attention is being paid to the environmental pollution caused by discarded grease. In this paper, calcium sulfonate complex grease (CSCG) was prepared by using green raw materials, namely poly-alpha-olefin oil as the base oil and complex calcium sulfonate soap as thickener . In order to improve the lubrication and damping performance of the grease, hexagonal boron nitride (hBN) and nano-Al 2 O 3 , which have the potential to replace toxic additives, are mixed into the grease in different mass proportions. The thickener structure of each grease was characterized and analyzed. According to the bearing vibration and life of the two key performance indicators, four-ball tests and bearing vibration tests under limited lubricant supply (LLS) were performed. The results show that CSCG with 0.75 wt% hBN and 0.25 wt% Al 2 O 3 (BN75AL25) has the best tribological and vibration suppression performance. The mean friction coefficient decreased by 11.3%, the wear scar diameter decreased by 6.1%, and the worn surface morphology improved significantly compared with CSCG. The frequency domain analysis showed that high, medium and low frequency vibrations were suppressed by 19%, 11.7% and 16.4%, respectively. In conclusion, BN75AL25 has the potential to become a green high-performance grease under LLS, which is worth further research and exploration.
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JOURNAL OF HAZARDOUS MATERIALS
·
2023
·
IF 13.6
Wei Shi,Xiaojing Liu,Yulei Liu,Dong Li,Xili Tong,Jun Ma,Lu Wang
Development of robust, reactive, and inexpensive catalyst for pollutants abatement with catalytic ozonation is of great significance. Herein, the effect of a robust and easy-recovery catalyst, Fe 2 O 3 /Al 2 O 3 -SiC, for the catalytic ozonation of hardly biodegradable COD (hard COD) in coking wastewater had been explored. Al-O-Si bond formed on modified SiC through the substitution of hydrogen in surficial Si-OH groups by Al 3+ . The Lewis acid sites improved the adsorption of ozone and facilitated the formation of ·OH and O 2 · − . For coking wastewater treatment , the removal ratio of hard COD and the generation speed of hydroxyl radical (R ct ) in the catalytic ozonation process were 71% and 253% higher than those in the ozonation group, respectively. Ozone utilization increased from 0.44 g COD removed/g O 3 in the ozonation group to 1.42 g COD removed/g O 3 in the Fe 2 O 3 /Al 2 O 3 -SiC catalytic ozonation group. In a full-scale application, Fe 2 O 3 /Al 2 O 3 -SiC catalytic ozonation decreased the consumption of O 3 to 60 mg L −1 and decreased the operation cost by 50%. These results provided an approachable way for sharing the extraordinary capacity of ozone for contaminants remediation in industrial applications.
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高影响因子
Crystals
·
2023
·Vol. 13
·期 1
·107
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IF 2.7
Shaocong He,Yehua Li,Xiao Zong,Shanghua Wu
In this work, Al2O3-AlN composite ceramics with high bending strength and thermal conductivity were fabricated by Digital Light Processing (DLP). The influence of AlN content on the rheological and cure behavior of Al2O3-AlN suspensions, as well as the microstructure, thermal conductivity, and bending strength of Al2O3-AlN ceramics, were systematically investigated. The result shows that the viscosity and cure ability of the suspensions were decreased with the increase of AlN content, which are beneficial to the spreading and printing accuracy of the suspensions. Besides, the bending strength of ceramics can be improved due to the residual stress by the introduction of AlN. Approaches were employed to minimize the formation of AlON in Al2O3-AlN ceramics by optimizing the amount of AlN and the sintering temperature. The thermal conductivity and bending strength of Al2O3-AlN ceramics were 31.72 ± 0.45 W/(m·K) and 572.73 ± 59.40 MPa, respectively, which are much higher than those of Al2O3ceramics fabricated under the same condition. Finally, complex-shaped Al2O3-AlN ceramics components have been successfully fabricated by DLP, which may provide an opportunity to broaden the application of Al2O3-AlN composite ceramics in heat dissipation components.Keywords:Al2O3-AlN composite ceramics;Digital Light Processing;mechanical properties;thermal conductivity
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Molecular Catalysis
·
2023
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IF 4.6
Xiaozhong Wang,Jiali Hu,Cai Xu,Yingqi Chen,Liyan Dai
Herein, a series of NiCu/Al 2 O 3 catalysts were prepared by impregnation method and subsequent thermal treatment under different reduction temperatures. The catalysts exhibited excellent catalytic activity for the amination of diethylene glycol (DEG), and satisfactory yield of tertiarybutylaminoethoxyethanol (TBEE) could be obtained. XRD, N 2 adsorption-desorption, SEM, TEM, XPS, and H 2 -TPR were employed to characterize the catalysts, the interaction between Ni and Cu on the catalytic activity was studied. It was found that NiCu alloy was formed after catalyst reduction, which strengthened the reduction ability of NiO and increased the number of Ni 0 active center, contributing to the enhanced catalytic activity. Moreover, the effects of reaction parameters on catalytic activity were explored. There was no need for a solvent, only 3 molar equivalents of tert‑butylamine (TBA) and 1 wt.% catalyst was required. After 7 h of reaction at 220 °C, satisfactory conversion (89.6%) and selectivity (84.6%) were obtained over the prepared catalyst. Cycle experiment demonstrated that the prepared catalyst retained excellent stability and reusability after six runs without significant loss of catalytic activity. This work provided an efficient catalyst for the catalytic amination of diethylene glycol with tert‑butylamine to TBEE.
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JOM
·
2023
·Vol. 75
·期 12
·5167-5175
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IF 2.6
Li Guanghui,Huang Jiahao,Sun Hu,Mang Changye,Hou Yanrui,Luo Jun
The novel one-step oxidation–volatilization process for separating MoO 3 from pelletized MoS 2 concentrate supported on a porous Al 2 O 3 -SiO 2 skeleton has been demonstrated to have superior diffusion efficiency compared to the traditional two-step oxidative roasting-sublimation approach. Optimal control of pellet phase and micro-structure evolutions is crucial for maintaining a stable and breathable pellet bed throughout the roasting process, which is essential for industrial application of the new process. This work determined the phase transformations of MoS 2 concentrate pellets during roasting, revealed the formation mechanisms of mullite whiskers from MoS 2 -Al 2 O 3 -SiO 2 system and thus achieved toughening control of roasted MoS 2 concentrate pellets with temperature programmed roasting (TPR). It is found that the intermediate product Al 2 (MoO 4 ) 3 can induce the low-temperature formation of mullite whisker. With TPR, the volatilization rate of molybdenum is 97.2%, and the compressive strength of mullite pellets reach 124.8 N. This study puts forward a feasible route with industrial significance.
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International Journal of Applied Ceramic Technology
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2022
·Vol. 20
·期 1
·527-533
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IF 2.328
Mengwen Zhang,Lutong Yang,Zhaosheng Li,Binyang Jiang
Al 2 O 3 –cBN has received considerable attention in the field of ceramic cutting tools due to its high hardness, high wear resistance, and low cost, but poor interfacial bonding affects the performance of the composite. In this study, a novel hot-forging process was used to prepare high-performance Al 2 O 3 –cBN composites using Ti(C,N) as a binder. The evolution of the morphology, phase, and microstructure of the hot-forged Al 2 O 3 –Ti(C,N)–cBN composites was determined, and the mechanical properties were measured. The relative density of the composites increases significantly after hot forging, and the deformation of the composites increases with the hot-forging temperature. The highest performing Al 2 O 3 –Ti(C,N)–cBN composite was prepared by hot forging at 1600°C and has a hardness of 20 GPa, a bending strength of 647 MPa and a fracture toughness of 5.37 MPa m 1/2 , which are superior to those of a directly hot-pressed sintered composite. However, at hot-forging temperatures higher than 1700°C, Al 5 O 6 N and TiB 2 are formed in the composite. In the composite hot forged at 1800°C, serrated grain boundaries promote the strength and toughness of the composite to 877 MPa and 6.76 MPa m 1/2 , respectively. Therefore, the novel hot-forging process is expected to enhance material properties.
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高影响因子
CHEMOSPHERE
·
2022
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IF 8.943
Yuqi Zhou,Hanqing Lv,Jin Lin,Tianyu Lv,Nan Wang,Heqing Tang,Lihua Zhu
This work reports a mechanochemical (MC) method for complete defluorination of perfluorooctanoic acid (PFOA) by using Al and Al 2 O 3 as milling agents. Both the Al/Al 2 O 3 molar ratio ( n Al / n Al 2 O 3 ) and the pre-thermal treatment of Al 2 O 3 strongly influenced the defluorination of PFOA. When commercial γ -Al 2 O 3 was pre-treated at 1200 °C, the use of Al and heat-treated γ -Al 2 O 3 with n Al / n Al 2 O 3 of 1: 1 led to PFOA defluorination of 100% after ball milling for 26 min at 350 rpm, being much higher than those (8.3%–58.1%) for using singlet milling agents or binary milling agents containing γ -Al 2 O 3 pre-heated at temperatures lower than 700 °C. It was clarified that the carboxylate-mediated adsorption of PFOA on Al 2 O 3 was essential for the MC decarboxylation as a degradation initiation step, and the in-situ generated electron on milled Al consequently caused the reductive dissociation of C–F bonds in the decarboxylation intermediate. A larger n Al / n Al 2 O 3 increased the in-situ electron generation rate ( r e ), and a higher heat-treatment temperature decreased OH − /H 2 O adsorbed on Al 2 O 3 to low the PFOA decarboxylation rate ( r dec ). The r e / r dec ratio determined defluorination pathways, and the percentage of the defluorination of PFOA in its total degradation including the generation of any degradation intermediates increased linearly with increasing r e / r dec .
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高影响因子
Materials Today Nano
·
2022
·
IF 13.364
H. Wang,Y. Liu,H. Wang,J. Song,D. Ma,Z. Dai
Efficient utilization of hydrocarbon fuels holds great significance for the current vehicle low-emission requirements and future carbon-neutral society. However, the scenario that limits the effective fuel use and combustion is the present undesirable hydrocarbon-cracking catalysts of low activity, serious coking, and easy degradation. To tackle these issues, we rationally designed and synthesized an active, anti-coking, and recyclable all-in-one zeolite@Ru–Al 2 O 3 catalyst on FeCrAl support by steam-assisted crystallization and atomic layer deposition . Ru nanoclusters dispersedly on ZSM-5 can boost the catalytic efficiency for hydrocarbon cracking and anti-coking, while the protective Al 2 O 3 thin layers further ensure the reusable economy. As for n-dodecane (C 12 H 26 ) cracking reaction, the ZSM-5@Ru–Al 2 O 3 showed a high unit activity up to 0.1253%·ml·mg −1 ·min −1 , low-carbon deposition rate, and the enhanced first-cycle carbon removal rate of 78.3% for recyclable use. Density functional theory (DFT) calculations have further confirmed that high catalytic efficiency and low-carbon deposition benefit from the timely adsorption of C 12 H 26 and timely transfer of reactant products at the composite interface. This work opens interesting possibilities for the rational design and fabrication of high-efficient, anti-coking, and recyclable hydrocarbon cracking catalysts through multifunctional structural regulations.
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NEW JOURNAL OF CHEMISTRY
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2022
·Vol. 46
·期 33
·15959-15966
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IF 3.925
Kai Zong,Ke Li,Ziyue Zhou,Lei Gong,Dongshun Deng
The uptake of NH3 in the industrial tail gas will improve the environmental quality for human health and ecology. Adsorption separation has the advantages of simple operation and low energy consumption. However, the relatively low adsorption capacity severely hinders its practical utilization. In this work, four glycerol-based deep eutectic solvents (DESs) were incorporated into porous silica gels (SGs) and Al2O3 with a large surface area and pore structure to form novel DES/SG and DES/Al2O3 composites. The obtained materials were systematically characterized by FTIR, SEM, BET, and TGA and further evaluated for NH3 adsorption. The results showed that the acidic GuSCN:Gly DES played an indispensable role for the high adsorption ability of the composite. 40 wt% GuSCN : Gly (1 : 3) DES/SG can capture 115.40 mg NH3 per gram adsorbent, which is better than most of the solid adsorption materials reported in the literature and even 30% higher than the original SG. The high adsorption capacity, outstanding thermal stability, and good reusability confirm the success of the present strategy. This study will provide a useful idea for designing DES-supported composites for NH3 separation applications.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2022
·
IF 9.136
Jianjie Chen,Yuming Tu,Gaoyan Shao,Fan Zhang,Zhiyong Zhou,Shichao Tian,Zhongqi Ren
A novel Calcium-loaded catalyst (Ca-C/Al 2 O 3 ) was prepared with a facile impregnation method, using polyethyleneimine (PEI)-polydopamine (PDA) as a coating agent and Al 2 O 3 as supporter. The prepared Ca-C/Al 2 O 3 catalyst showed a higher treatment performance for high salt organic wastewater, and removal rate of chemical oxygen demand (COD) was enhanced from 32.5% to 64.4% comparing with single ozonation. Besides, it also showed a good catalytic performance comparing with other catalysts reported in different literature. Catechol groups and reactive amine groups in the PEI-PDA coating worked as anchoring points for metal ions, facilitating the formation of dispersed calcium sites (Ca-O and Ca-N). Calcium sites and different types of nitrogen (graphite nitrogen, pyrrolic nitrogen, and pyridinic nitrogen) were identified as the active sites for the catalytic reaction. The analysis of electron paramagnetic resonance (EPR) and radical quenching tests revealed that hydroxyl radical (•OH) and singlet oxygen ( 1 O 2 ) were the reactive oxygen species (ROS) for treatment of high salt organic wastewater. According to the above results, the prepared Ca-C/Al 2 O 3 catalysts showed a good catalytic permanence and used for advanced treatment of high salt organic wastewater.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Zhongyang Zheng,Heping Li,Fangjian Li,Liyu Zheng,Shenming Yin,Xinyun Wang,Youwei Yan
Two-dimensional materials, impermeable to various mediums, have ignited the great interest in developing multifunction nanocomposite coatings. Even though Al 2 O 3 has excellent thermal and chemical stability, it is hard to obtain Al 2 O 3 nanosheets from their non-lamellar structured bulk counterparts. In this work, we have developed a bottom–up strategy to synthesize several-nanometer thick Al 2 O 3 nanosheets by taking graphene oxide as the templates, and further improved their dispersibility by modifying them with poly-dopamine (PDA). These PDA-modified Al 2 O 3 nanosheets were then successfully integrated into the nanosized ZrO 2 coating to enhance its anti-corrosion and gas permeation reduction properties. With the Al 2 O 3 nanosheets inserted, corrosion resistance and deuterium resistance of the ZrO 2 coating were increased by 1000% and 1557%, respectively, both of which were above two orders of magnitude higher than that of the 321 steel substrate. The significant improvements achieved by Al 2 O 3 nanosheets demonstrate their capacity to effectively block the diffusion of both ions and deuterium atoms. This work not only offers a new platform for fabricating nanosheets from non-lamellar structured materials, but also indicates tremendous potential of Al 2 O 3 nanosheets as a novel filler for developing high-performance functional coatings.
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CATALYSIS TODAY
·
2022
·
IF 6.562
Peng Bai,Tao Zhou,Xiaohua Wang,Xiaofei Liu,Yi Wang,Yue Wang,Edgar Muhumuza,Yonghui Zhang,Pingping Wu
A series of γ-Al 2 O 3 supported gold-palladium (Au-Pd) alloy nanoparticles (NPs) catalysts were synthesized by a one-pot approach applying mercapto-propyl-trimethoxysilane (MPTMS) as an anchoring ligand. Homogeneously dispersed Au-Pd alloy NPs were observed on the prepared catalysts and their catalytic performance in benzyl alcohol partial oxidation was investigated. Results showed that the highest benzaldehyde yield was achieved on catalyst Au-Pd/7%MPTMS-γ-Al 2 O 3 with a benzaldehyde selectivity of 90%. By establishing the structure-performance relationship, the high activity of catalysts with MPTMS modification was attributed to the anchoring and dispersion effect of MPTMS on Au-Pd NPs, while the high benzaldehyde selectivity was due to the formation of more surface Lewis acid sites after introducing MPTMS, protecting the benzaldehyde from over-oxidation to byproducts.
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