ACS Catalysis
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2016
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IF 9.307
Gang Liu,Zhi-Jian Zhao,Tengfang Wu,Liang Zeng,Jinlong Gong
Supported VOx catalysts are promising for use in propane dehydrogenation (PDH) because of the relatively superior activity and stable performance upon regeneration. However, the nature of the active sites and reaction mechanism during PDH over VOx-based catalysts remains elusive. We examined active species by attaining various fractions of V5+, V4+, and V3+ ions by adjusting the surface vanadium density on an alumina support. The results reveal a close relationship between TOF and the fraction of V3+ ion, indicating that V3+ was more active for PDH. In situ diffuse reflectance infrared Fourier transform spectroscopy showed the same strong adsorbed species during both propane dehydrogenation and propylene hydrogenation. The results indicated that such an intermediate may correspond to V species containing a C═C bond, i.e., V–C3H5, and a reaction mechanism was proposed accordingly.
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POWDER TECHNOLOGY
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2017
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IF 2.942
Yuehua Sun,Chaoqun Peng,Xiaofeng Wang,Richu Wang,Junliang Yang,Dou Zhang
Al 2 O 3 polyelectrolyte suspensions containing PAA-PEI complexes have been used for direct ink writing to fabricate complex 3D structures with micro-sized feature. Zeta potential and rheological behavior of the Al 2 O 3 polyelectrolyte suspensions were investigated. The isoelectric point of Al 2 O 3 particles shifts from alkaline region to acidic region as the [COOH]:[NH x ] ratio increases from 0.12 to 3. The rheological results reveal that the 40 vol% Al 2 O 3 suspension with [COOH]:[NH x ] ratio of 0.3 and 15 mg/mL methylcellulose at pH 10 is the optimal suspension for direct ink writing, due to its good shear thinning and viscoelastic behavior . The filament in lattice structure prepared using this polyelectrolyte suspension can maintain its original shape with little spreading. In the micrograph of sample sintered at 1600 °C for 2 h, the uniform size of grains indicates that the structure is fully sintered under this sintering condition.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2017
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IF 3.454
Heping Li,Zhiqiang Ke,Jing Li,Lihong Xue,Youwei Yan
Pores and cracks are usually inevitable in the coatings fabricated by plasma spraying . Herein, thermal chemical reaction technique was developed as an effective low-temperature strategy for addressing this issue. Dense α-Al 2 O 3 /AlPO 4 coating was synthesized on the surface of the plasma sprayed Al 2 O 3 -based coating by thermal chemical reaction at 500 °C. The α-Al 2 O 3 /AlPO 4 composites permeated into the coating and effectively filled up the pores and cracks inside. The sealed coating showed a uniform and dense morphology. The hydrogen permeation rate of the sealed coating sharply decreased by a factor of 15, which further confirmed its significantly improved compactness. In addition, the coating exhibited good thermal shock resistance and bond strength after sealing. Considering its low-temperature heat treatment, facile fabrication process and wide applicability, thermal chemical reaction method can be potentially used as a cost-saving strategy for sealing plasma sprayed ceramic coatings .
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CARBOHYDRATE RESEARCH
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2012
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IF 2.332
Liqiang Wu,Zhikui Yin
A simple and clean synthesis of per- O -acetylation carbohydrate derivatives has been accomplished by treatment of sugars with a stoichiometric quantity of acetic anhydride under solvent-free conditions in the presence of sulfonic acid functionalized nano γ-Al 2 O 3 as an efficient and environmentally benign catalyst.
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Science China-Chemistry
·
2017
·Vol. 60
·期 7
·920-926
·
IF 4.132
Li Yan,Cheng Haiyang,Zhang Chao,Zhang Bin,Liu Tong,Wu Qifan,Su Xinluona,Lin Weiwei,Zhao Fengyu
Hexamethylenediamine (HMDA) is an important reagent for the synthesis of Nylon-6,6, and it is usually produced by the hydrogenation of adiponitrile using a toxic reagent of hydrocyanic acid. Herein, we developed an environmental friendly route to produce HMDA via catalytic reductive amination of 1,6-hexanediol (HDO) in the presence of hydrogen. The activities of several heterogeneous metal catalysts such as supported Ni, Co, Ru, Pt, Pd catalysts were screened for the present reaction in supercritical ammonia without any additives. Among the catalysts examined, Ru/Al 2 O 3 presented a high catalytic activity and highest selectivity for the desired product of HMDA. The high performance of Ru/Al 2 O 3 was discussed based on the Ru dispersion and the surface properties like the acid-basicity. In addition, the reaction parameters such as reaction temperature, time, H 2 and NH 3 pressure were examined, and the reaction processes were discussed in detail.
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Materials Today Communications
·
2024
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IF 3.7
Zhiwei Xu,Xiangxing Zhou,Ke Peng,Tiechui Yuan,Ruidi Li,Zhihui Zhou
In this study, fast hot-pressing sintering and the power of B 4 C and 1/3/5/7 wt% Al 2 O 3 were used to make B 4 C-Al 2 O 3 composite ceramics at 2000°C and 30 MPa. The toughening mechanism was thoroughly examined, and the impact of Al 2 O 3 content on the microstructures and mechanical characteristics of B 4 C-Al 2 O 3 composite ceramics was examined. The comprehensive mechanical properties of B 4 C-Al 2 O 3 composite ceramics were optimized by adding 3 wt% Al 2 O 3 , the relative density, flexural strength , fracture toughness, and Vickers hardness reached 99.38 %, 616.2 MPa, 5.45 MPa∙m 1/2 , and 35.91 GPa, respectively. The strengthening mechanism of B 4 C-Al 2 O 3 composite ceramics is that grain refinement and grain boundary movement are hindered by second-phase particles. And the toughening mechanism is crack deflection and Al 2 O 3 grain cracking.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2025
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IF 8.3
Changgui Wu,Mengke Xu,Feifei Song,Biao Ma,Fuling Li,Chengxiang Shi,Zhen-Feng Huang,Ruijie Gao,Xiangwen Zhang,Lun Pan,Ji-Jun Zou
Monobenzyltoluene (H0-BT) is a promising liquid organic hydrogen carrier (LOHC), and continuous reaction process represents a more favorable approach in the large-scale hydrogen storage. In this work, the impacts of Pt loading and reaction conditions on the dehydrogenation performance of perhydro-monobenzyltoluene (H12-BT) over Pt/Al 2 O 3 were conducted in a fixed-bed reactor. The results indicate that the dehydrogenation activity of catalyst shows a volcano type as increasing Pt loading, reaching a maximum at 3 wt%. 1 wt% Pt loading is the most appropriate in consideration of the dehydrogenation activity and hydrogen purity. High reaction temperature and low pressure can facilitate dehydrogenation kinetics but result in the undesired byproducts, therefore, the optimal reaction conditions are 320 °C and 0.7 MPa. Additionally, the dehydrogenation performance of H12-BT and perhydro-dibenzyltoluene (H18-DBT) were compared under the similar conditions, revealing that H12-BT may be a superior hydrogen storage carrier.
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Materials Research Express
·
2025
·Vol. 12
·期 1
·015304
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IF 2.2
Shibo Ren,Jianlin Xu,Lei Niu,Penghui Yang
In this study, the surface flame retardancy of polycarbonate (PC) was improved and the impact of flame retardants on the substrate were minimized by pre-mixing Al2O3 particles with dichloromethane, an infiltration promoter, to form a suspension, and then treating PC with the suspension to form an Al2O3 infiltration layer. For this layer, its structure and composition were characterized, its flame retardancy was evaluated, and its flame retardancy mechanism was investigated. The characterization results confirmed that an Al2O3 infiltration layer was successfully prepared on the PC surface under the aid of dichloromethane and that the involvement of dichloromethane induced certain microscopic pores and voids in the PC, with some dichloromethane remaining within the surface infiltration layer. The surface Al2O3 infiltration layer mainly served as a condensed-phase flame retardant. The infiltration layer prepared using a suspension with a dichloromethane-to-Al2O3 mass ratio of 24:1 not only exhibited a good overall performance but also achieved the best improvement in the PC flame retardancy, such as an increase in the vertical burning rating from HB to V-0, as well as the LOI increased from 24 to 31.3, and a 35% reduction in the peak heat release rate compared to those of pure PC.
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MOLECULES
·
2024
·Vol. 29
·期 18
·4391
·
IF 4.2
Kaihui Hua,Zhijing Wu,Weijie Chen,Xiuan Xi,Xiaobing Chen,Shuyan Yang,Pinhai Gao,Yu Zheng
Titanium dioxide (TiO2) is widely employed in the catalytic degradation of wastewater, owing to its robust stability, superior photocatalytic efficiency, and cost-effectiveness. Nonetheless, isolating the fine particulate photocatalysts from the solution post-reaction poses a significant challenge in practical photocatalytic processes. Furthermore, these particles have a tendency to agglomerate into larger clusters, which diminishes their stability. To address this issue, the present study has developed Al2O3–SiO2–TiO2composite semiconductor porous ceramics and has systematically explored the influence of Al2O3and SiO2on the structure and properties of TiO2porous ceramics. The findings reveal that the incorporation of Al2O3augments the open porosity of the ceramics and inhibits the aggregation of TiO2, thereby increasing the catalytic site and improving the light absorption capacity. On the other hand, the addition of SiO2enhances the bending strength of the ceramics and inhibits the conversion of anatase to rutile, thereby further enhancing its photocatalytic activity. Consequently, at an optimal composition of 55 wt.% Al2O3, 40 wt.% TiO2, and 5 wt.% SiO2, the resulting porous ceramics exhibit a methylene blue removal rate of 91.50%, and even after undergoing five cycles of testing, their catalytic efficiency remains approximately 83.82%. These outcomes underscore the exceptional photocatalytic degradation efficiency, recyclability, and reusability of the Al2O3–SiO2–TiO2porous ceramics, suggesting their substantial potential for application in the treatment of dye wastewater, especially for the removal of methylene blue.
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CATALYSIS COMMUNICATIONS
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2024
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IF 3.4
Yang Zhang,Qizhuang Zou,Ruiqi Fang,Hua Tan,Hongbing Ji,Yingwei Li
Yolk-shell nanoreactors feature numbers of advantages in promoting catalytic performance. This work demonstrates the fabrication of yolk-shell Fe 3 O 4 @SiO 2 /Al 2 O 3 - T ( T = 500–900 °C) from metal-organic framework. Characterizations indicate the Fe 3 O 4 yolk and SiO 2 /Al 2 O 3 shell of the obtained nanoreactors. Fe 3 O 4 @SiO 2 /Al 2 O 3 –800 showed excellent performance in furfural acetalization to 2-(dimethoxymethyl)furan, achieving a 97% yield at 60 °C, atmospheric pressure within 5 h. Control experiments reveal the high reactivity of Fe 3 O 4 yolks for furfural acetalization, and acidic Al species are favorable for reactivity promotion. Besides, porous SiO 2 /Al 2 O 3 shells facilitate mass transfer and increase the accessibility of active sites, also contribute to the high performance and stability.
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JOURNAL OF POWER SOURCES
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2024
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IF 8.1
Hongmei Qin,Ziwei Li,Shiyu Qin,Yanda Jiang,Man Liu,Ling Zhou,Siyu Yu,Shan Wang,Chuanxi Xiong
High-temperature polymer dielectric capacitors are urgently needed in the new-generation electronic and electrical systems. Whereas, current commercial polymer represented by polyimide (PI) suffer from exponentially growing conduction loss at high temperatures and high electric fields, and hence extremely low discharged energy density and sharply declined charge-discharge efficiency. In this work, we developed superior Al 2 O 3 /PI/Al 2 O 3 sandwich films with drastically improved capacitive energy storage performance via atomic layer deposition (ALD) technology. Notably, resultant PI hybrid dielectrics deposited by 130 nm-thickness Al 2 O 3 (Al 2 O 3 /PI/Al 2 O 3 -130nm) exhibits the highest breakdown strength and the lowest leakage current density compared to pristine PI. Consequently, Al 2 O 3 /PI/Al 2 O 3 -130nm delivers a discharged energy density of 4.9 J/cm 3 at 25 °C and 3.3 J/cm 3 at 150 °C, as high as 2.7 times and 3.3 times respectively that of near PI film. Moreover, PI hybrid dielectrics can operate steadily under 200 MV/m and 150 °C during 10,000 cycle measurements. The excellent performance is mainly attributed to the improved barrier height of the electrode/PI interface endowed by deposited large-bandgap Al 2 O 3 .This work provides a scalable approach to enable excellent high-temperature energy storage performance of polymer dielectrics and promising to promote the application of PI for capacitive energy storage under harsh conditions.
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JACS Au
·
2025
·
IF 8.7
Xuan Bie,Yukun Pan,Xiaowei Wang,Shiyu Zhang,Jiahui Hu,Xiaoxiao Yang,Qinghai Li,Yanguo Zhang,Robert E. Przekop,Yayun Zhang,Hui Zhou
Gas sources rich in CO2 derived from biomass/waste gasification, anaerobic digestion, or industrial carbon capture often contain impurities such as H2S, H2O, and NH3, which can significantly hinder catalyst performance. Here, we show the role of NH3 on the reverse water–gas shift (RWGS) reaction over a commercial Cu/ZnO/Al2O3 catalyst, examining its effects on both the catalytic activity and the catalyst structure. We found that NH3 reversibly decreases CO2 conversion immediately by suppressing carbonate hydrogenation and CO desorption. This effect intensifies with an increase in NH3 concentration but decreases at higher temperatures. However, prolonged exposure (over 100 h) to RWGS conditions in the presence of 1.4% NH3 leads to near-total and irreversible deactivation of the Cu/ZnO/Al2O3 catalyst. Under NH3 exposure, the catalyst loses Cu+ sites on the surface, causing a spatial separation of Cu and ZnO. Finally, to address this challenge, we propose a novel strategy to mitigate NH3 inhibition by decomposing NH3 into N2 and H2.
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