JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Lijun Yue,Wanjun Zhao,Jinfang Li,Ruifang Wu,Yongzhao Wang,Hongxi Zhang,Yongxiang Zhao
The impact of Indium (In) doping upon the catalytic performance of Pd-Cu/Al 2 O 3 for carbon monoxide preferential oxidation (CO-PROX) in hydrogen (H 2 ) rich atmosphere at low temperature has been studied. A series of catalysts with extremely low palladium (Pd) loading (0.06 wt%) are synthesized by the facile co-impregnation method. When the In/copper (Cu) atomic ratio equals 0.25, Pd-Cu-In 0.25 /Al 2 O 3 can keep 40% CO conversion and 100% carbon dioxide (CO 2 ) selectivity at least 120 min at 30 °C, which is significantly superior to the catalytic performance of Pd-Cu/Al 2 O 3 . The elaborate characterization findings reveal that the added In species to Pd-Cu/Al 2 O 3 causes Indium oxide (In 2 O 3 ) to generate, which produces the interaction of In 2 O 3 with Pd-Cu/Al 2 O 3 , further promoting the dispersion of copper chloride hydroxide (Cu 2 Cl(OH) 3 ). Moreover, the modification of In facilitates the re-oxidation of Pd 0 to Pd + through reducing the formation of palladium hydride (PdH x ) during the CO-PROX reaction. Meanwhile, the addition of In leads to the decrease of Cu + electron cloud density, making it easier to be oxidized to Cu 2+ . Collectively, the easy re-oxidation of Pd 0 and Cu + is favorable to fulfill the Wacker cycle between Pd and Cu species, thus improving the catalytic performance for CO-PROX.
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PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Weiwei Li,Wenying Zhou,Na Lin,Mengting Liu,Jing Liu,Ying Wang,Bo Wang,Dengfeng Liu,Mengxue Yuan
High dielectric permittivity ( ε ) but low loss polymeric composites have presented wide applications. To elevate the overall dielectric performances in raw zinc oxide (ZnO)/polyvinylidene fluoride (PVDF), the prepared aluminum oxide (Al 2 O 3 ) encapsulated ZnO core-shell particles were incorporated into the polypropylene (PP) modified PVDF blend to generate high ε and breakdown strength ( E b ) but low loss nanocomposites. The Al 2 O 3 shell’ impacts on the dielectric performances of the ZnO/PVDF-PP were investigated. The results indicate that the insulating Al 2 O 3 shell induces concurrent interparticle polarization and intraparticle polarization leading to evidently enhanced ε , and effectively restrains the leakage current resulting in simultaneously suppressed loss and elevated E b in the nanocomposites. Further, the introduced alumina shell can induce traps and capture charge carrier thus resulting in enhanced E b . Through facilitating the intra-particle polarization and repressing the charge migration, the 50 wt% ZnO@Al 2 O 3 /PP-PVDF present a much higher ε (16) and E b (11 kV/mm) but lower dielectric loss (0.08), respectively, far exceeding 9.6, 9 kV/mm and 0.18 at 100 Hz for the unmodified ZnO nanocomposites. Further, the dielectric parameters of the nanocomposites can be effectively tuned via tailoring the Al 2 O 3 shell thickness. The fitting via the Havriliak-Negami equation theoretically interpret the experimental results and uncover the underlying multiple polarization mechanisms. This work provides deep insight into the design and development of flexible polymeric nanodielectrics with eminent integrated dielectric properties for appealing applications in electronic device and power system.
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Crystals
·
2024
·Vol. 14
·期 5
·452
·
IF 2.4
Sen Yang,Ruiqing Ba,Jingnan Hong,Jing Li,Jingdong Guo,Xinghui He,Hongwei Zhang,Naihe Yi,Weibing Ma
Pure lanthanum hexaboride (LaB6) ceramics were prepared using powders of different grain sizes. The ceramics could reach a relative density of 98.2% at high temperatures and pressures, but had a low flexural strength (136.9 MPa). LaB6ceramics were synthesized using ZrO2-Al2O3-TiO2(ZAT) as sintering additives. The ceramics demonstrate high density and excellent mechanical properties. The hot pressure sintering (HPS) method was utilized in the synthesis of the ceramics. Investigations were conducted on the effects of ZAT content, as well as the effects of the sintering temperature and pressure on the sintering behavior, microstructure, and mechanical and electrical properties of LaB6ceramics. LaB6ceramics fabricated with a ZAT addition of 6 wt.%, at a sintering temperature of 1700 °C, and under a pressure of 50 MPa, exhibited superior sintering and electrical properties, including a relative density of 97%, a conductivity of 7.2 MS/m, a flexural strength of 281.5 MPa, and a Vickers hardness of 21.2 GPa. The LaB6ceramics synthesized in this research exhibit promising potential as electron-emitting cathodes for field emission applications.
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COMPOSITES COMMUNICATIONS
·
2025
·
IF 7.7
Guibin Zhang,Lijun Wei,Yueyue Liang,Furu Zhang,Xineng Zhu,Yingge Xu,Fulong Yang,Shenmao Dong,Rui Zhang,Yongqian Shen
With the increase of power density in electronic devices, the electromagnetic (EM) compatibility and heat dissipation problems of electronic devices are becoming increasingly serious. Herein, MOF-derived FeCoNi@carbon (MOF-FeCoNi@C) composites were obtained by a simple one-step carbon thermal reduction of FeCoNi-MOF/polyacrylonitrile (PAN), and then combined with Al 2 O 3 to construct the thermally conductive and microwave absorbing silicone rubber sheets with dual functional characteristics (MOF-FeCoNi@C/Al 2 O 3 /SR). The MOF-confined strategy could achieve controllable growth and uniform distribution of FeCoNi alloy nanoparticles, optimize impedance matching, enhance the EM synergy and EMWs attenuation. Therefore, when the amount of MOF-FeCoNi@C added was 15 wt%, the minimum reflection loss ( RL min ) was -35.4 dB at 13.6 GHz with a thickness of 1.5 mm and an effective bandwidth (EBW) reached 4.1 GHz. Furthermore, the sample exhibits excellent thermal conductivity under the combined action of MOF-FeCoNi@C and Al 2 O 3 . As a consequence, this work utilizes a simple preparation process to develop a new type of absorber and promote its application in rubber sheets, provides a new idea for the research of microwave absorbing materials and has important practical significance.
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Catalysis Science & Technology
·
2018
·Vol. 8
·期 6
·1621-1631
·
IF 5.365
Yuxi Gao,Xiaodong Wu,Robin Nord,Hanna Härelind,Duan Weng
The sulphur resistance and regeneration strategy of soot oxidation catalysts are critical to the application of catalytic diesel particulate filters (CDPFs). In the present work, Pt/MnOx–CeO2/Al2O3, Pt/Al2O3 and MnOx–CeO2/Al2O3 catalysts were sulphated and regenerated with ammonia. The soot oxidation activity of poisoned Pt/MnOx–CeO2/Al2O3 was recovered completely after 30 min reduction in 500 ppm NH3 at 550 °C. The amount, distribution and structure of sulphates were studied comprehensively for the sulphated and regenerated samples by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, CO chemisorption and transmission electron microscopy (TEM). The NO oxidation of Pt catalysts was found to depend strongly on the particle size distribution, surface exposure and oxidation state of the precious metal. This, as well as the effect of the remaining surface sulphates, helped the regenerated catalysts achieve even higher catalytic activity for soot oxidation.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Jiaxin Huang,Chongshuai Gao,Shijun Liu,Xiaorui Du,Wenguang Zhou,Chenguang Wang
Alloying Cu-based catalysts by doping other metals at single atom level is an effective way to improve their hydrogenation performance of biomass-derived molecules. However, the application of Cu-based single atom alloy catalyst in the catalytic hydrogen transfer reaction system remains to be unrevealed. Here, we develop Al 2 O 3 supported CuPd alloy catalysts, among which the single atom alloy catalyst with Pd dispersed in single atomic level on the surface was successfully obtained by controlling the metal amount, such as Cu 8 Pd 1 /Al 2 O 3 with the Cu/Pd Molar ratio of 8: 1. The catalytic performance for furfural hydrodeoxygenation to 2-methylfuran of the CuPd/Al 2 O 3 catalysts, using isopropanol as a hydrogen donor, shows a volcano-type relationship to the Cu/Pd ratio. The highest 2-methylfuran yield (81% at 220 °C) was achieved on the single atom alloy catalyst Cu 8 Pd 1 /Al 2 O 3 . The underlying reaction mechanism of furfural hydrodeoxidation on Cu 8 Pd 1 /Al 2 O 3 was revealed by a series of isotopic labeling experiments, that the furfural was firstly hydrogenated to be furfuralcohol by a metal site-mediated catalytic transfer hydrogenation pathway, and then the furfuralcohol was converted to be 2-methylfuran by a Lewis acid-mediated furan ring activation route. The weak Lewis acid site that formed by single atom Pd alloyed with CuO matrix on Cu 8 Pd 1 /Al 2 O 3 was proposed as the active site for the highly selective generation of 2-methylfuran.
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Catalysts
·
2024
·Vol. 14
·期 12
·885
·
IF 3.8
Yulin Sun,Yiwei Zhang,Baoqing Hou,Yong He,Wubin Weng,Yanqun Zhu,Zhihua Wang
Formaldehyde (HCHO) is known as one of the important indoor organic pollutants. How to remove and decompose the low concentration of formaldehyde at room temperature is important for indoor environments. Catalytic ozonation is an efficient method to thoroughly remove HCHO at room temperature, with high efficiency and few byproducts. A series of MnOx/γ-Al2O3catalysts were prepared in this work via the impregnation method and treated with different reagents (acid, alkali, and H2O2) to evaluate their catalytic activity for HCHO removal. The results showed that MnAl-II (acid treatment) performed well in activity tests, reaching a nearly 100% HCHO conversion at an O3/HCHO of 2.0 and attaining a CO2selectivity of above 95% at an O3/HCHO of 3.0 at 30 °C, with almost no ozone residual existing. The larger specific surface area, abundant oxygen vacancies, and higher number of acid sites contributed to the excellent performance of MnAl-II. Stability and H2O resistance tests of MnAl-II were also conducted. To reveal the intermediate product formation and further investigate the reaction mechanism of HCHO ozonation, in-situ DRIFTS measurement was carried out combined with DFT calculations.
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CATALYSIS LETTERS
·
2025
·Vol. 155
·期 4
·1-8
·
IF 2.4
Zhang Qian,Li Yuanzheng,Pan Zhengyi,Wang Guang-Hui
Catalytic transfer hydrogenation (CTH) of α , β -unsaturated aldehydes to α , β -unsaturated alcohols over metal oxide catalysts is of potential for industrial application. Herein, we have developed a Ni/f - Al 2 O 3 catalyst comprising atomically dispersed Ni δ + (2 < δ < 3) species on porous leaf-like Al 2 O 3 , over which a > 97% yield of furfuryl alcohol (FOL) from CTH of furfural (FFR) is obtained with a turnover frequency (TOF) of 216 h − 1 . Most importantly, the catalyst can be recycled at least 6 times without obvious loss of activity. Its superior catalytic performance can be attributed to the abundant and stable Ni δ + -type acid-base pairs on the surface of Ni/f - Al 2 O 3 .
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Catalysis Science & Technology
·
2024
·Vol. 14
·期 14
·4058-4067
·
IF 4.4
Yang You,Aijie Xu,Yao Lv,Lide Yang,Xuan Tang,Jie Tang,Yanglong Guo,Yao Cui,Wangcheng Zhan,Li Wang,Yun Guo,Sheng Dai
Complete oxidation of propane has drawn great attention in the fields of automotive emission control and volatile organic compound elimination. However, it is challenging to achieve high activity of this reaction due to the stability of propane. We here utilize a facile solvothermal method to construct tri-coordinated Al (AlIII) sites on the as-synthesized ST-Al2O3 support to alter the properties of supported Pt species. It is demonstrated that AlIII sites facilitate the dispersion and electron enrichment of supported Pt sites. Thus, Pt/ST-Al2O3 exhibits a superior activity toward complete propane oxidation, showing a 6.7-fold improvement in the turnover frequency over commercial Pt/Al2O3 catalysts. Meanwhile, Pt/ST-Al2O3 possesses a distinct reaction route originating from its stronger C–H and C–C cleavage capability, while having excellent activity not only in complete propane oxidation but also in the complete oxidation of other alkanes (CH4, C2H6, and n-C4H10). In addition, the AlIII construction strategy is successfully extended to more cases, e.g., Pd/ST-Al2O3 with higher Pd dispersion and electron density. This work provides a promising strategy for the control of the oxide support for advanced design and synthesis of alkane oxidation catalysts.
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ACS Catalysis
·
2025
·
IF 13.1
Zhitong Zhou,Weixiang Guan,Xiaoli Pan,Aiqin Wang,Tao Zhang
One-pot amination coupling of vicinal diols toward the synthesis of pyrazines provides an efficient and economically viable route to access N-heterocycles from biomass, yet the current methodology relies on a fragile homogeneous catalyst system, which limits the sustainability of the chemistry. In this work, we developed a highly efficient heterogeneous catalyst 0.8Pt/13CeO2/Al2O3 which afforded diverse substituted pyrazines from readily available vicinal diols and ammonia with a yield up to 94% under mild reaction conditions and could be reused at least 6 times without obvious activity decay. Compared to the Pt/Al2O3 catalyst, the 0.8Pt/13CeO2/Al2O3 catalyst exhibited a 30-fold faster conversion rate of diols and an increased pyrazine selectivity from 48% to 79%. Characterizations revealed that doped CeO2 improved the dispersion of Pt, increased the electron density on the Pt sites, optimized the acid/basic property of the catalyst, and enhanced the adsorption strength and dehydrogenation ability of diols. All these features contributed to the increased activity and selectivity.
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ACS Omega
·
2024
·
IF 3.7
Guolan Dou,Lingling Gao,Xiaoxing Zhong
In this study, melamine-urea-formaldehyde/nano-Al2O3 (MUF/nano-Al2O3) composite gel foams were produced by foaming with CO2 generated by CaCO3 and phosphoric acid. Nano-Al2O3 was introduced to the MUF matrix based on the optimum formulation obtained by the response surface methodology based on Box–Behnken design, and the effects of nano-Al2O3 on the cell structure, apparent density, compressive strength, pulverization ratio, thermal stability, and thermal conductivity were investigated. The results revealed that the introduction of nano-Al2O3 could improve the foaming and mechanical properties of MUF with smaller cell sizes, a narrower cell size distribution, decreased apparent density, higher compressive strength, and a decreased pulverization ratio. MUF/nano-Al2O3-1.5 with the most uniform cell size distribution had a 21% increased compressive strength, but its apparent density and pulverization ratio decreased by 10% and 13%, respectively. Although the char yield decreased with the introduction of nano-Al2O3, MUF/nano-Al2O3 composite foams still presented improved thermal stability under 300 °C, with a thermal conductivity of 0.068 W/(m·K) and a limiting oxygen index of more than 30%. Therefore, MUF/nano-Al2O3 composite gel foam could be employed in coal mines as thermal insulation sealing material due to its better cell structure and mechanical properties.
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PubMed
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Junjing Li,Wanxin Dang,Yaqian Liu,Liang Wang
The efficiency of an electrocatalytic system with filtered Pd-loaded membrane electrodes was investigated to improve the mass transfer process of the electrocatalytic system. A Pd/CGC/Al 2 O 3 membrane electrode (5 mg·cm −2 graphite + 10 wt% graphene + 5 wt% carbon black) was prepared on the tubular Al 2 O 3 membrane substrate. The results showed that the membrane electrode could realize the complete removal of chlorpheniramine maleate (CPM) 120 min. Furthermore, the Pd/CGC/Al 2 O 3 membrane electrode exhibited good tolerance to sulfites, and the electrocatalytic activity was almost unaffected in the presence of NO 3 – , Cl − , CO 3 2– , and HCO 3 – in the wastewater. The Pd/CGC/Al 2 O 3 membrane electrode surface was interconnected to form a three-dimensional porous membrane structure through the introduction of carbon materials. The membrane electrode had a larger specific surface area and the metal Pd nanoparticles were uniformly loaded on the surface of CGC/Al 2 O 3 tubular electrode. Combined with the analysis of quenching experimental data, the removal mechanism of CPM on Pd/CGC/Al 2 O 3 membrane electrode was proposed. The Pd/CGC/Al 2 O 3 membrane electrode had good stability over 7 cycles and could be adapted to the electrocatalytic hydrodechlorination of chlorinated PPCPs in different environments, which is promising for certain applications.
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