CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Xi-Guang Wang,Lu-Yang Qiao,Li-Yuan Xu,Yun-Yun Zeng,Zhi-Shen Huang,Shan-Shan Zong,Jin-Xiang Wang,Zhang-Feng Zhou,Yuan-Gen Yao
The intrinsic nature of irreducible oxides (e.g. Al 2 O 3 ) makes it hard to tune the charge state of supported late-transition metals, then difficult to adjust the selectivity of catalysts in CO 2 hydrogenation. Herein, we find that modifying the Pd/Al 2 O 3 catalyst with alkali metals (especially potassium) is efficient to boost the CO formation in CO 2 hydrogenation. In comparison to Pd/Al 2 O 3 , approximately twenty-fold promotion in reverse water–gas shift (RWGS) rate was achieved on K-modified catalysts with proper K/Pd proportions. Combined structural characterizations demonstrate that the enhanced Pd-O interactions through K mediation stabilize the ca. 2 nm sized Pd particles as well as the electron-deficient state of Pd, which are robust enough during long-termed evaluation with undamped performance. In situ spectroscopy unveils a bi-dentate *HCOO associated reaction mechanism taking effect on alkali-modified catalysts, which contributes to ∼ 100 % of CO selectivity and 3318.1 mmol∙g Pd -1 ∙h −1 of CO formation rate at 340°C.
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JOURNAL OF ADVANCED OXIDATION TECHNOLOGIES
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2016
·Vol. 19
·期 2
·358-365
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IF 0.738
Yanfang Liu,Guixia Li,Zhili Zhang,Xiang Gao,Jianrui Niu,Junna Zhao,Zaixing Li
γ-Al 2 O 3 supported Manganese and Ferric oxide (Mn-Fe/Al 2 O 3 ) were synthesized and used as catalyst for ozonation of bisphenol A (BPA) in aqueous solution. It was conducted in a semi-batch reactor under different operational conditions, i.e., varying initial pH, ozone flow rate, initial BPA concentration and catalyst dosage. The results indicated that the presence of Mn-Fe/Al 2 O 3 lead to a great enhancement in ozonation of BPA. Using 5 g/L Mn-Fe/Al 2 O 3 evaluated BPA (50 mg/L) removal efficiency up to 84.1% under particular reaction conditions, while that of the single ozonation process was 48.5%. The influence of tert-butanol demonstrated that initiation of hydroxyl radicals was involved and plays an important role in catalytic ozonation. The decrement of solution pH in catalytic ozonation was much higher than that in ozone alone, indicating much small molecule acids produced in catalytic ozonation process. The repeated use the Mn-Fe/Al 2 O 3 proved that it had a good reusability and stability.
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FUEL
·
2017
·
IF 4.601
Wei-Tu Li,Xian-Yong Wei,Xue-Ke Li,Xiang-Xue Liu,Zhan-Ku Li,Zhi-Min Zong
Catalysts Ni/γ-Al 2 O 3 , Mg 2 Si/γ-Al 2 O 3 , and Ni-Mg 2 Si/γ-Al 2 O 3 were prepared. Their activities for catalytic hydroconversions (CHCs) of some lignite-related model compounds were examined. For the CHCs of oxydibenzene (ODB), benzyloxybenzene, and oxybis(methylene)dibenzene, the suitable loadings of Ni and Mg 2 Si are 33 and 20% in Ni-Mg 2 Si/γ-Al 2 O 3 , respectively, and the optimal reaction conditions are 4 MPa of initial hydrogen pressure, 240 °C, and 2 h, under which ODB was almost completely converted to cyclohexane. The formation of possible intermediates during the CHC of ODB was discussed. Ni-Mg 2 Si/γ-Al 2 O 3 was proposed to have 3 functions, i.e., activating H 2 to biatomic active hydrogen (H⋯H), releasing H − , and heterolytically splitting H⋯H to release H − as well, resulting in the hydrogenation of aromatic rings and the hydrocracking of C O bonds, respectively.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2016
·
IF 3.349
Lijun Xue,Di Zhang,Yongqiang Xu,Xinmei Liu
γ-Al 2 O 3 without amorphous domains was synthesized by cation-anion double hydrolysis method. The mesopore size in the range of 3.9–8.5 nm was easily controlled by regulating crystallization temperature, solution pH value and the concentration of NaAlO 2 . The introduction of MoO 3 to the γ-Al 2 O 3 via impregnation method can lead to a decrease of specific surface areas, pore sizes and pore volumes of the supports. The less steric hindrance of the larger mesopores (particularly 8.5 nm) exhibits the more Lewis acid sites over the γ-Al 2 O 3 . The MoO 3 /γ-Al 2 O 3 possesses more Bronsted acid sites compared to Lewis. The thiophene compounds can be adsorbed both on the supports and catalysts. The acid sites can facilitate the interaction between the thiophene compounds and catalysts (or supports). The more adsorbed thiophene and dibenzothiophene on the catalysts is attributed to the coordinately unsaturated metal sites and Bronsted acid sites on the surface of the catalysts. Of note is the supports and catalysts with larger pore size (especially 8.5 nm) could promote the adsorption of thiophene compounds. It demonstrates that there is pore confinement effect in the hydrodesulfurization catalysts.
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COMPOSITES SCIENCE AND TECHNOLOGY
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2016
·
IF 3.897
Yong Hu,Guoping Du,Nan Chen
Insulating materials for electronic packaging should ideally have high strength and thermal conductivity . Ceramic/polymer composite is one of the candidates for such materials. In this work, Al 2 O 3 /epoxy composites with very high flexural strength and thermal conductivity were prepared using a new processing technique consisting of the gelcasting, sintering and vacuum infiltration methods. Al 2 O 3 green bodies were first formed by gelcasting. After being degreased at 600 °C, the green bodies were sintered at different temperatures from 1200 °C to 1500 °C, and porous Al 2 O 3 ceramic skeletons with different porosity were resulted. The porosity was readily controlled by the sintering temperature . Higher sintering temperature resulted in lower porosity and larger average grain size in the Al 2 O 3 ceramic skeletons. Epoxy was vacuum infiltrated into the sintered porous Al 2 O 3 ceramic skeletons to form Al 2 O 3 /epoxy composites by curing. High Al 2 O 3 loadings up to 70 vol.% in the composites were achieved. The flexural strength and thermal conductivity of the Al 2 O 3 /epoxy composites were found to reach 305 MPa and 13.46 W m −1 K −1 , respectively. These results are remarkably higher than those previously reported in the literature. This work provides an effective approach for fabricating high performance ceramic/polymer composites for electronic packaging.
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APPLIED PHYSICS LETTERS
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2016
·Vol. 109
·期 9
·
IF 3.142
Yao Manwen,Peng Yong,Xiao Ruihua,Li Qiuxia,Yao Xi
SrTiO 3 /nano Al 2 O 3 inorganic nanocomposites were prepared by using a conventional sol-gel spin coating process. For comparison, SrTiO 3 films doped by equivalent amount of sol-Al 2 O 3 have also been investigated. Aluminum deposited by using vacuum evaporation was used as the top electrode. The nanocomposites exhibited a significantly enhanced dielectric strength of 506.9 MV/m, which was increased by 97.4% as compared with the SrTiO 3 films doped with sol-Al 2 O 3 . The leakage current maintained of the same order of microampere until the ultimate breakdown of the nanocomposites. The excellent electrical performances are ascribed to the anodic oxidation reaction in origin, which can repair the internal and/or surface defects of the films.
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ELECTROCHIMICA ACTA
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2015
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IF 4.504
Bo Liang,Siqi Tang,Qingbai Jiang,Chuangsheng Chen,Xu Chen,Shengliang Li,Xuehui Yan
This paper presents the preparation and characterization of a series of PEO-PMMA composites containing different lithium salts (LiClO 4 or LiTFSI) with or without nano-Al 2 O 3 . Nano-Al 2 O 3 is added to the polymer electrolytes to alter the morphology, ionic conductivity , interfacial and thermal shrinkage properties. Nano-Al 2 O 3 can effectively improve the stability of the polymer electrolyte membrane interface. The tensile strength of the PEO-PMMA-LiTFSI-Al 2 O 3 electrolyte membrane is 3.24 MPa at room temperature . The study shows that the ion conductivities at room temperature for PEO-PMMA-LiTFSI (EO/Li + = 10) and PEO-PMMA-LiTFSI-Al 2 O 3 (EO/Li + = 10) are 6.71 × 10 −7 S/cm and 9.39 × 10 −7 S/cm, respectively. A good dimensional stability was observed for PEO-PMMA-LiTFSI with a thermal shrinkage of 8.7%. The electrochemical windows of PEO-PMMA-LiTFSI and PEO-PMMA-LiTFSI-Al 2 O 3 are all stable up to 4.6 V versus Li + /Li, which makes them good electrolyte candidates of lithium ion batteries with high-potential cathodes.
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RSC Advances
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2014
·Vol. 4
·期 89
·48317-48321
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IF 3.708
Yun Yu,Weimin Hou,Xuebing Hu,Yang Yu,Le Mi,Lixin Song
A novel superhydrophobic Al2O3 microfiltration membrane was prepared by the layer-by-layer assembly of TiO2 coating with subsequent fluorination grafting surface treatment by 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The influence of surface morphology on membrane superhydrophobicity, pore size diameter distributions and pure water permeability of the different membranes were studied. By optimizing the grafting parameters, a needle-like surface of grafted TiO2-coated Al2O3 membrane with a water contact angle of 169.5° was obtained. The pure water permeability of different membranes varied from 100 l m−2 h−1 bar−1 before grafting to 3–5 l m−2 h−1 bar−1 after grafting, and the grafted superhydrophobic membrane showed excellent water repellence. The novel superhydrophobic membrane is shown to be promising for liquid–liquid and gas–liquid separation.
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Catalysts
·
2014
·Vol. 4
·期 3
·276-288
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IF 0
Haiyang Cheng,Weiwei Lin,Xiaoru Li,Chao Zhang,Fengyu Zhao
Series catalysts of Ru-SnOx/Al2O3with varying SnOxloading of 0–3 wt% were prepared, and their catalytic activity and selectivity have been discussed and compared for the selective hydrogenation ofm-dinitrobenzene (m-DNB) tom-nitroaniline (m-NAN). The Ru-SnOx/Al2O3catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and hydrogen temperature-programmed reduction (H2-TPR) and desorption (H2-TPD). Under the modification of SnOx, the reaction activity increased obviously, and the best selectivity tom-NAN reached above 97% at the complete conversion ofm-DNB. With the increasing of the SnOxloading, the amount of active hydrogen adsorption on the surface of the catalyst increased according to the H2-TPD analysis, and the electron transferred from Ru to SnOxspecies, as determined by XPS, inducing an electron-deficient Ru, which is a benefit for the absorption of the nitro group. Therefore, the reaction rate and product selectivity were greatly enhanced. Moreover, the Ru-SnOx/Al2O3catalyst presented high stability: it could be recycled four times without any loss in activity and selectivity.Keywords:Ru catalyst;SnOxdoping;hydrogenation;m-dinitrobenzene;m-nitroaniline;catalyst recycling
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INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES
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2014
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IF 2.216
Yan Qin,Zhilong Rao,Zhixiong Huang,Hui Zhang,Jinrong Jia,Fuzhong Wang
Ceramizable heat-resistant organic adhesive (CHA) was prepared by using preceramic polymer polysiloxane as matrix, TiB 2 ceramic powder and low melting point glass powder as additives. The curing mechanism, thermal stability properties, phase composition after pyrolysis , structural evolution of bonding layer and bonding mechanism of the adhesive were investigated by FTIR, TGA-DSC, XRD , SEM, FESEM and bonding strength tests. Results of bonding tests showed the maximum shear strength of the joints was 21 MPa when heat treatment at 1200 °C for 2 h in air. Polysiloxane resin acted as crosslinking adhesive at low temperatures and tended to convert to ceramic bonding layer at high temperatures, resulting from ceramization reaction with active fillers. The formation and growth of ceramic phase after heat treatment enhanced the thermal stability and bonding performance of the adhesive at high temperature.
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JOURNAL OF MATERIALS SCIENCE
·
2014
·Vol. 49
·期 16
·5772-5781
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IF 2.305
Shi Junjun,Zhou Yuming,Zhang Yiwei,Zhou Shijian,Zhang Zewu,Kong Jie,Guo Mingpeng
Magnesium (Mg)-modified mesoporous alumina with different type and content of Mg was prepared and then used as the support for platinum-tin catalyst in propane dehydrogenation. It was found that the property of Mg in Al 2 O 3 varied with the way of the addition of Mg precursors. For the grafted Mg species, the connection between Al 2 O 3 and Mg was increased by the forming of Mg–O–Al bonds in the inner surface of Al 2 O 3 pore. While for the traditional impregnation, Mg was attached loosely to the outer Al 2 O 3 surface by the aggregation of MgO. Moreover, modifying the internal framework of Al 2 O 3 by suitable content of Mg can enhance the interaction between Sn and support, leading to more amounts of tin in their oxidized states, which was beneficial to enhance the interaction of Pt with SnO x species. As a result, agglomerations of metallic particles were suppressed and the catalyst exhibited the best catalytic performance in terms of activity and stability.
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CELLULOSE
·
2017
·Vol. 24
·期 4
·1889-1899
·
IF 3.417
Xu Qi,Wei Chengzhuo,Fan Lingling,Peng Shuo,Xu Weilin,Xu Jie
The bacterial cellulose (BC)/Al 2 O 3 nanofibrous composite membrane as a lithium-ion battery separator has been successfully prepared by coating Al 2 O 3 on the BC nanofibers through a simple in situ thermal decomposition of Al(NO 3 ) 3 · 9H 2 O. Thermal treatment tests show that the BC/Al 2 O 3 composite membrane is thermally stable at a high temperature of 200 °C while great shrinkage is observed for the commercial PP-PE-PP membrane. Moreover, the BC/Al 2 O 3 membrane is evaluated to have large porosity and excellent electrolyte uptake, consequently giving rise to larger ionic conductivity, lower interfacial resistance as well as better electrochemical stability. The half lithium-ion battery assembled with the BC/Al 2 O 3 separator demonstrates large discharge capacity and good cycling performance, suggesting that the BC/Al 2 O 3 membrane can be used as a lithium-ion battery separator.
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