JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
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2023
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IF 10.9
Pingsheng Lai,Xuan Ge,Caijuan Shi,Jianqiang Li,Fan Yang,Wenquan Lu,Jianguo Li,Qiaodan Hu
Despite its significance in both fundamental science and industrial applications, the glass-forming transition in the Al 2 O 3 -Y 2 O 3 (AY) refractory system is not yet fully understood due to the elusive structure evolution upon cooling. Here, atomic-scale structural changes in AY-bearing melts with different compositions and temperatures are tracked by employing in situ high-energy synchrotron X-ray diffraction and empirical potential structure refinement simulation. We find that the glass-forming abilities (GFA) of AY-bearing melts are intriguingly correlated with the dependence of melt structure on temperature. In the case of the Al 2 O 3 and Y 3 Al 5 O 12 (YAG), the observed large structural changes from superheating to undercooling melt (i.e., higher temperature susceptibility) correspond to a low GFA. Conversely, the 74Al 2 O 3 –26Y 2 O 3 (AY26) melt, with the smallest temperature susceptibility, exhibits the highest GFA. Simulation models illustrate that the temperature susceptibility of melt is associated with its atomic arrangement, especially the stability of cation-cation pairs. A balanced network (in AY26 melt), where the unsteady OAl 3 tri-clusters are minimized and steady apex-to-apex connections between adjacent network units are abundant, contributes to stabilizing cationic interactions. This, in turn, fosters the formation of large-sized Al-O-Al rings, which topologically facilitates the subsequent glass-forming transition. Our findings provide new structural insight into the GFA of AY-bearing melts and may expand to other unconventional glass-forming systems to accelerate glassy materials design.
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高影响因子
Materials Today Communications
·
2023
·
IF 3.8
Xiaojing Xi,Juan Li,Huajun Chen,Rui Wang
In this work, we prepared mesoporous η-Al 2 O 3 nanofiber with tunable pore size using diverse surfactants . The as-prepared mesoporous η-Al 2 O 3 nanofiber was characterized by a combination of various physicochemical techniques. The influence of surfactants types and polymerization degree on surface morphology and adsorption performance of mesoporous η-Al 2 O 3 nanofiber was compared. The results of transmission electron microscopy (TEM), low-angle X-ray diffraction (XRD) and N 2 adsorption–desorption isotherm prove the existence of mesoporous structure in η-Al 2 O 3 nanofiber. Polyethylene glycol (PEG) is favored over polyether (PPG) in the preparation of mesoporous η-Al 2 O 3 nanofiber, and PEG with a lower degree of polymerization is beneficial to form well-defined mesoporous structure. The η-Al 2 O 3 nanofiber (PEG600) has the highest specific surface area and the best adsorption performance, followed by the η-Al 2 O 3 nanofiber (PEG2000), and then the η-Al 2 O 3 nanofiber (PPG). Both the adsorption isotherm and the adsorption kinetics equation prove that the adsorption mechanism of methylene blue on mesoporous η-Al 2 O 3 nanofiber is the combination of chemical and multilayer adsorption. This work provides a new avenue to prepare mesoporous η-Al 2 O 3 nanofiber with tunable pore size for the application of mesoporous material in battery, adsorbent, catalytic and biomedical carrier.
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高影响因子
Materials
·
2023
·Vol. 16
·期 16
·5652
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IF 3.4
Dongjiang Zhang,Rui Yu,Xuelei Feng,Xuncheng Guo,Yongkang Yang,Xiqing Xu
In this work, Al2O3nanoceramics were prepared by spark plasma sintering of amorphous powders and polycrystalline powders with similar particle sizes. Effective comparisons of sintering processes and ultimate products depending on starting powder conditions were explored. To ensure near-full density higher than 98% of the Al2O3nanoceramics, the threshold temperature in SPS is 1450 °C for polycrystalline Al2O3powders and 1300 °C for amorphous powders. The low SPS temperature for amorphous powders is attributed to the metastable state with high free energy of amorphous powders. The Al2O3nanoceramics prepared by amorphous powders display a mean grain size of 170 nm, and superior mechanical properties, including high bending strength of 870 MPa, Vickers hardness of 20.5 GPa and fracture toughness of 4.3 MPa∙m1/2. Furthermore, the Al2O3nanoceramics prepared by amorphous powders showed a larger dynamic strength and dynamic strain. The toughening mechanism with predominant transgranular fracture is explained based on the separation of quasi-boundaries.
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PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
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IF 4.2
Hua Yang,Zhang Zhang,Yongsheng He,Peng Wang,Zhuangzhuang Ren,Lizhi Wu,Yu Tang,Li Tan
Ni-based catalysts have been widely investigated in the partial oxidation of methane (POM). However, sintering and carbon deposition are severe problems for Ni-based catalysts in the POM reaction. Here, Ni/Al2O3 catalysts with Al2O3 supports prepared by different synthesis methods are used to investigate the effect of strong metal–support interaction (SMSI) and their relationships to the catalytic performance. As a result, the different strengths of SMSI between Ni species and various Al2O3 supports contribute to generating different contents of the reduced metallic Ni0 sites in the catalysts, which affects the catalytic activity in the POM reaction obviously. The surface unsaturated pentahedral coordination Al3+ centers supply SMSI in the Ni/Al2O3-H catalyst to prevent the catalyst from sintering and coking in the POM reaction, which results in better catalytic activity and catalyst stability. A new view is provided to solve the design of stable metal oxide catalysts by utilizing their SMSI effect.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2023
·
IF 8.6
Shubin Cheng,Qian Lei,Coner Deng,Weixin Lei,Honglin Chen
A green protocol for refining industrial chemicals containing formaldehyde (FA) impurities is presented here for the first time. FA, as an unreactant or a byproduct, causes separation problems in many industrial processes. It can be removed to a level of less than 1 ppm with easily separable methanol formation using commercial Cu/ZnO/Al 2 O 3 catalyst at atmospheric pressure in the absence of external hydrogen. The formation of methanol is achieved by the transfer of hydrogen species generated with the assistance of water to free FA, affording high methanol selectivity (62 %). By investigating potential intermediates and implementing deuterium labeling experiments, together with carbon and hydrogen balance calculations, a plausible pathway of water-assisted FA removal is proposed. Moreover, the in situ generated hydrogen species can be transferred directly into unsaturated compounds for selective reduction.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2023
·
IF 9.9
Jianfeng Li,Wenli Suo,Yuena Huang,Minglin Chen,Haowen Ma,Chuang Liu,Huan Zhang,Kun Liang,Zhengping Dong
The selective hydrogenation of alkynes to alkenes is widely applied in the chemical industry; nevertheless, achieving highly selective hydrogenation with high catalytic activity is considerably challenging. Herein, ultrafine PdCu bimetallic nanoparticles encapsulated by high-surface-area mesoporous α-Al 2 O 3 were prepared by high-temperature calcination–reduction using a porous organic framework (POF) as the template. As-obtained PdCu@α-Al 2 O 3 exhibited a high selectivity of 95% for the semi-hydrogenation of phenylacetylene as a probe reaction under mild reaction conditions. The separation of continuous Pd atoms and modification of the Pd electronic state by Cu atoms suppressed β-hydride formation and alkene adsorption, contributing to high selectivity for the catalytic hydrogenation of alkynes. The catalytic activity was maintained after 7 cycles due to the strong interaction between the PdCu bimetallic nanoparticles and α-Al 2 O 3 as well as the encapsulation effect of mesoporous α-Al 2 O 3 . Thus, the current work provides a facile strategy for fabricating high-surface-area mesoporous α-Al 2 O 3 -supported catalysts for industrial catalysis applications.
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高影响因子
MOLECULES
·
2023
·Vol. 28
·期 24
·7978
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IF 4.6
Jie Gu,Lipeng Liu,Rongrong Zhu,Qiqi Song,Hanqing Yu,Pengjie Jiang,Changqing Miao,Yuxiang Du,Rui Fu,Yaxiong Wang,Yan Hao,Huazheng Sai
A large quantity of coal fly ash is generated worldwide from thermal power plants, causing a serious environmental threat owing to disposal and storage problems. In this work, for the first time, coal fly ash is converted into advanced and novel aerogel fibers and high-purity α-Al2O3. Silica–bacterial cellulose composite aerogel fibers (CAFs) were synthesized using an in situ sol-gel process under ambient pressure drying. Due to the unique “nanoscale interpenetrating network” (IPN) structure, the CAFs showed wonderful mechanical properties with an optimum tensile strength of 5.0 MPa at an ultimate elongation of 5.8%. Furthermore, CAFs with a high porosity (91.8%) and high specific surface area (588.75 m2/g) can inherit advanced features, including excellent thermal insulation, stability over a wide temperature range, and hydrophobicity (contact angle of approximately 144°). Additionally, Al2O3was simultaneously extracted from the coal fly ash to ensure that the coal fly ash was fully exploited. Overall, low-cost woven CAFs fabrics are suitable for wearable applications and offer a great approach to comprehensively use coal fly ash to address environmental threats.Keywords:silica aerogel fiber;coal fly ash;bacterial cellulose;high strength;thermal insulation;Al2O3
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Wenju Tao,Jiaxin Yang,Liyu Chen,Yifan Zhang,Shaohua Wu,Jiaming Li,Zhaoshun Liu,Jingui He,Zhaowen Wang
Green and efficient recovery of solid waste from aluminum electrolysis is of great significance. In this study, the sediment generated by aluminum electrolysis at the bottom of the waste tank was used as an alternative F resource. A new process of low-temperature acidification roasting with Al 2 O 3 as the catalyst was performed to effectively recover F. The results of the single-factor experiment showed that a long reaction time and high acid-material ratio were conducive to improving the extraction rate of F. Under the conditions of 275 °C and 5 doses of sulfuric acid, the optimum F extraction rate was realized by roasting for 4 h with 1 dose of Al 2 O 3 as the catalyst. The results of the XRD, SEM and chemical analyses showed that NaAl(SO 4 ) 2 was the main component produced in the calcination reaction using Al 2 O 3 as the catalyst, rather than NaHSO 4 (produced in the calcination process without a catalyst). This ensured complete combination of H and F, which greatly improved the extraction rate of F (from 80.76 to 99.76%). The proposed mechanism can provide not only an optimization scheme for the roasting of waste sediment at the furnace bottom, but also a more effective recovery treatment for the acidification roasting of other solid wastes with low Al 2 O 3 content.
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COLLOID AND POLYMER SCIENCE
·
2023
·Vol. 301
·期 8
·989-999
·
IF 2.4
Hu Tao,Xu Weichuan,Li Dong,Wang Song,Wang Yuxiang,Wu Caijin,Tan Liqiang
Extensive use of Al 2 O 3 nanoparticles in consumer and industrial products has led to concerns about their potential environmental impacts in the recent years. In most studies concerning Al 2 O 3 aggregation and disaggregation, more was to consider the single factor that influences their environmental behaviors. Understanding the combined abiotic factors that influence the fate, transport, and stability of nanoparticles in a complex aquatic system has become extremely important. Here, we reported and analyzed the major abiotic factors such as typical solution pH, electrolyte cations in different valences (Na + and Ca 2+ ), and the presence of humic acid (HA) that influence the stability, aggregation, and disaggregation behaviors of Al 2 O 3 nanoparticles in a complex aquatic system. Dynamic light scattering technique combined with fluorescence spectroscopic analysis was used to explore the aggregation mechanisms. Experimental results indicated that Al 2 O 3 nanoparticle stability was mainly controlled by the steric hindrance, van der Walls, and electrostatic interactions between HA and Al 2 O 3 nanoparticles. Aggregation kinetics and attachment efficiency studies induced by the addition of Na + and Ca 2+ cations confirmed that divalent electrolytes could reduce the large energy barrier between the charged colloidal particles more efficiently, and induce a more aggressive aggregation of the particles. Additionally, the bridging effect of HA with Ca 2+ was also an important mechanism for the aggregation enhancement, which had been confirmed by the fluorescence excitation-emission matrix (EEM) spectra analysis. These findings are useful in understanding the environmental challenges of inorganic colloidal particles in natural environments.
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高影响因子
Journal of Energy Storage
·
2023
·
IF 9.4
Heqing Tian,Zhaoyang Kou,Yinsheng Yu,Songzhen Tang,Xuehong Wu
In this paper, a coupled optimization method of optical and thermal performance was explored by us. The microscopic structure of NaCl-Al 2 O 3 based composite phase change material (CPCM) was established, the thermal properties were obtained by means of molecular dynamics (MD) simulations combined with experiments. The first principle calculations were also carried out to investigate the optical performance of the CPCM. The results indicated that the addition of nano Al 2 O 3 can effectively improve the thermal performance and thermal stability of CPCM, when the mass fraction of Al 2 O 3 nanoparticles in CPCM are 2.2 wt% and 7.2 wt%, the mass loss of CPCM samples were 0.14 % and 0.016 % after 100 times cycle, and the thermal conductivity and specific heat capacity can be increased by 15.45 % and 7.63 % at most. In addition, it was found that the optical performance of the CPCM can be also significantly improved. The microscopic coupled optimization mechanism was successfully revealed by the calculation of phonon density of state and band structures, which is desired to be a candidate approach to improve the photo-thermal conversion efficiency of the heat absorber contained in CSP (concentrating solar power) system.
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高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Fuming Miao,Shuai Zhang,Xueliang Sun,Yamin Li,Ruize Shang,Wenli Wu,Weizhou Jiao,Youzhi Liu
In this study, Mn-CoO X / γ -Al 2 O 3 (MCA) was prepared by impregnation for catalytic ozonation of phenol in a rotating packed bed (RPB), and the effects of high gravity factor ( β ), liquid flow rate ( Q L ), initial solution pH and gaseous ozone concentration ( C O 3 ) on the mineralization of phenol were explored. The results show that the degradation rate of phenol ( η phenol ) reaches 100% at 9 min and the mineralization rate ( η TOC ) reaches 95.01% at 45 min under conditions of β = 104, C O 3 = 80 mg L -1 , Q L = 80 L/h, and pH = 6. Compared with the bubbling reactor (BR)/MCA/O 3 and O 3 /RPB systems, the η TOC of the MCA/O 3 /RPB system is increased by 25.81% and 40.85%, respectively. The electron paramagnetic resonance (EPR) results reveal that hydroxyl radical (·OH) plays a critical role in the degradation of phenol by MCA catalyzed ozonation. The quenching experiment using tertiary butyl alcohol (TBA) as a scavenger of ·OH reveals that the ratio of direct and indirect degradation of phenol is 16:9. The intermediates generated during the degradation of phenol were detected by gas chromatography-mass spectrometry (GC–MS), and possible degradation pathways were proposed. In conclusion, MCA-catalyzed ozonation and RPB have a synergistic effect on ·OH initiation and improve the degradation and mineralization of phenol. This study provides a new perspective for the degradation of phenol.
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高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yang Jia,Tao Li,Xiaoguang Chen,Haitao Xue,Weibing Guo,Cuixin Chen
Al 2 O 3 ceramic and 304 stainless steel were brazed with AgCuTi filler in this paper. Two kinds of composite filler were prepared by adding Cu foam and Cu foam covered with graphite (Gr-Cu foam) to relieve the residual stress of the joints. The effects of Cu foam pore size on the joints were investigated in detail, and the evolution mechanism of the joints was analyzed. Graphite-reinforced Cu foam was fabricated by spraying graphite for the first time. Results showed that the extremely low coefficient of thermal expansion of graphite and the good energy absorption performance of Cu foam were both conducive to reducing the thermal residual stress during the cooling process. Gr-Cu foam with pre-filled pores was used to solve the problems of structural dissolution of Cu foam and unfilled solder in Cu foam pores to a certain extent. And it played a key role in preventing the diffusion of metal atoms. The graphite on the surface of the Cu foam generated TiC in the brazing seam. The TiC and Cu foam promoted the formation of the TiCu strengthening phase. Furthermore, when the pore size of the Gr-Cu foam was 150 μm, the maximum shear strength of the joint was 246.84 MPa. This value was about 40% higher than that of Cu foam with the same pore size. The residual stresses of joint with and without graphite-reinforced were calculated, respectively, for both conditions. The reduction of residual stress was found after adding the graphite during brazing.
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